CN114660718A - A photonic integrated chip for miniaturized interferometric fiber optic gyroscope - Google Patents

Abstract

The invention relates to an interference type fiber-optic gyroscope, in particular to a photonic integrated chip for a miniaturized interference type fiber-optic gyroscope. The invention solves the problems that the traditional interference type optical fiber gyroscope is difficult to realize miniaturization, high insertion loss and high production cost. A photon integrated chip for a miniaturized interference type fiber-optic gyroscope comprises an SOI platform, four bending waveguides, two integrated silicon-based Y waveguides and a cascade type integrated silicon-based polarizer; a first integrated silicon-based Y waveguide as a source Y branch; a second integrated silicon-based Y waveguide as an interferometric Y-branch; the cascade integrated silicon-based polarizer comprises N integrated silicon-based polarizing units; the core layer waveguides of the first to Nth integrated silicon-based polarization units are sequentially connected in series, and the head end of the main straight waveguide section of the source Y branch is connected with the head end of the main straight waveguide section of the interference type Y branch sequentially through the core layer waveguides of the first to Nth integrated silicon-based polarization units. The invention is suitable for a miniaturized interference type optical fiber gyroscope.

Description

A photonic integrated chip for miniaturized interferometric fiber optic gyroscope

technical field

The invention relates to an interferometric fiber optic gyroscope, in particular to a photonic integrated chip for miniaturized interference type fiber optic gyroscope.

Background technique

Interferometric fiber optic gyroscope is an angular velocity sensor based on the Sagnac effect, which is widely used in aviation, aerospace, navigation and other fields. In the traditional interferometric fiber optic gyroscope, since each optical device (light source, photodetector, polarization-maintaining fiber ring, piezoelectric ceramic phase modulator, two couplers, spatial filter, polarizer) are discrete optical devices On the one hand, it is difficult to achieve miniaturization of the interferometric fiber optic gyroscope, and on the other hand, the interferometric fiber optic gyroscope has the problems of high insertion loss and high production cost. Based on this, it is necessary to invent a photonic integrated chip for miniaturized interferometric fiber optic gyroscope to solve the problems of difficulty in miniaturization, high insertion loss and high production cost of traditional interferometric fiber optic gyroscope.

SUMMARY OF THE INVENTION

In order to solve the problems of difficulty in miniaturization, high insertion loss and high production cost of traditional interferometric fiber optic gyroscopes, the present invention provides a photonic integrated chip for miniaturized interferometric fiber optic gyroscopes.

The present invention adopts following technical scheme to realize:

A photonic integrated chip for miniaturized interferometric fiber optic gyroscope, comprising an SOI platform, four curved waveguides, two integrated silicon-based Y-waveguides, and a cascaded integrated silicon-based polarizer;

Four curved waveguides, two integrated silicon-based Y-waveguides, and cascaded integrated silicon-based polarizers are all processed on the SOI platform;

The end faces of the four curved waveguides are all flush with the right end face of the SOI platform, and the length of the third curved waveguide is not equal to the length of the fourth curved waveguide;

Each of the integrated silicon-based Y-waveguides includes a main straight waveguide section; the tail end of the main straight waveguide section is extended with a tapered waveguide section with a narrow head end and a wide tail end; the tail end of the tapered waveguide section is extended with two The transition straight waveguide section, and the two transition straight waveguide sections are symmetrically distributed along the width direction of the main straight waveguide section; a coupling slit is formed between the two transition straight waveguide sections; One arc waveguide segment, and two arc waveguide segments are symmetrically distributed along the width direction of the main straight waveguide segment; the coupling slit is filled with a subwavelength grating A, and the length direction of each grid bar of the subwavelength grating A is the same as that of the main straight waveguide segment. The width directions of the straight waveguide segments are the same; the thickness of the main straight waveguide segment, the thickness of the tapered waveguide segment, the thickness of the two transition straight waveguide segments, the thickness of the two arc waveguide segments, and the thickness of the subwavelength grating A are all the same; The width of the straight waveguide segment, the width of the head end of the tapered waveguide segment, the width of the two transition straight waveguide segments, and the width of the two arc waveguide segments are all the same; the width of the tail end of the tapered waveguide segment is equal to the two transition straight waveguide segments The sum of the width of and the width of the coupling slit;

The first integrated silicon-based Y-waveguide serves as the source Y-branch; the second integrated silicon-based Y-waveguide serves as the interferometric Y-branch; the tail end of the first circular arc waveguide segment of the source Y branch is connected to the head end of the first curved waveguide Connection; the tail end of the second circular arc waveguide segment of the source Y branch is connected with the head end of the second curved waveguide; the tail end of the first circular arc waveguide segment of the interferometric Y branch is connected to the head end of the third curved waveguide end connection; the tail end of the second circular arc waveguide segment of the interferometric Y branch is connected to the head end of the fourth curved waveguide;

The cascaded integrated silicon-based polarizer includes N integrated silicon-based polarizing units; N is a positive integer, and 2≤N≤9;

Each of the integrated silicon-based polarizing units includes a core layer waveguide, a subwavelength grating B, and two tapered waveguides; the core layer waveguide includes a semi-circular arc waveguide segment, and two extending and extending at both ends of the semi-circular arc waveguide segment. A straight waveguide segment; each grid of the subwavelength grating B is a semicircular arc grid, and the opening direction of the semicircular arc grid is consistent with the opening direction of the semicircular arc waveguide segment; the period of the subwavelength grating B is a fixed value ; The duty cycle of each grid bar of subwavelength grating B gradually decreases from the inside to the outside; the first grid bar of subwavelength grating B is parallel coupled to the outside of the semicircular arc waveguide segment; The ends are wide and the end is narrow, and the head ends of the two tapered waveguides are respectively butted with both ends of the first grid bar of the subwavelength grating B; the two tapered waveguides are respectively coupled in parallel to the two straight waveguide sections. Outside; the thickness of the semicircular arc waveguide segment, the thickness of the two straight waveguide segments, and the thickness of the subwavelength grating B are all the same; the thicknesses of the two tapered waveguides are both greater than the thickness of the subwavelength grating B; The width and the width of the two straight waveguide segments are the same; the width of the head end of the two tapered waveguides is larger than the width of the first grid bar of the subwavelength grating B; the width of the two tapered waveguides and the two straight waveguide segments is The coupling spacing is equal to the coupling spacing between the first grid bar of the subwavelength grating B and the semicircular arc waveguide segment;

The core layer waveguides of the first to Nth integrated silicon-based polarizing units are connected in series in sequence, and the head end of the main straight waveguide section of the source Y branch passes through the core layer waveguides of the first to Nth integrated silicon-based polarizing units in sequence. The head-end connection of the main straight waveguide section of the interferometric Y-branch.

When in use, the present invention is connected with a fiber array, a light source, a photodetector, a polarization-maintaining fiber ring, and a piezoelectric ceramic phase modulator to form a miniaturized interferometric fiber optic gyroscope, as shown in Figure 9 (the end face of the first curved waveguide is connected to the The head end face of the first optical fiber of the optical fiber array is coupled, and the tail end of the first optical fiber of the optical fiber array is connected with the photodetector. The tail end face of the second curved waveguide is coupled with the head end face of the second optical fiber of the optical fiber array, and the optical fiber The tail end of the second optical fiber of the array is connected with the light source. The tail end face of the third curved waveguide is coupled with the head end face of the third optical fiber of the optical fiber array, and the tail end of the third optical fiber of the optical fiber array is phase-modulated by piezoelectric ceramics is connected with one end of the polarization maintaining fiber ring. The tail end face of the fourth curved waveguide is coupled with the head end face of the fourth fiber in the fiber array, and the tail end of the fourth fiber in the fiber array is connected with the other end of the polarization maintaining fiber ring. ).

The working process of the miniaturized interferometric fiber optic gyroscope is as follows: the light beam emitted by the light source is first filtered by the source Y branch (to filter out the high-order mode), and then filtered by the cascade integrated silicon-based polarizer (to filter out the TM mode and the high-order mode), Then it is split by the interferometric Y branch (the split ratio is 5:5) to form two beams. The two beams propagate in opposite directions through the polarization-maintaining fiber ring (the first beam propagates counterclockwise through the polarization-maintaining fiber ring, and the second beam propagates clockwise through the polarization-maintaining fiber ring), and then returns to the interferometric Y branch The light is combined, and at the same time, the interference is carried out through the interferometric Y branch and the Sagnac effect is formed. The phase difference information generated by the Sagnac effect enters the photodetector sequentially through the cascade integrated silicon-based polarizer and the source Y branch.

In the above working process, considering the connection between the interferometric Y branch and the third bending waveguide, the coupling between the third bending waveguide and the third fiber of the fiber array, and the connection between the interferometric Y branch and the fourth bending waveguide At the connection, the coupling between the fourth curved waveguide and the fourth fiber of the fiber array will reflect the Michelson interference effect. The following relationship is satisfied between the length L4 of the four curved waveguides and the decoherence length L _dc of the light source: |L3-L4|>L _dc ; the calculation formula of the decoherence length L _dc of the light source is: L _dc =(λ·λ) /(Δλ _FWHM ); in the formula: λ is the central wavelength of the light source, and Δλ _FWHM is the spectral bandwidth of the light source. The single-mode, single-polarization filtering properties of the cascaded integrated silicon-based polarizers allow any signal that differs from the input state (eg, differences in spatial mode or polarization mode) to be substantially eliminated. Specifically, the non-reciprocal phase shift mechanism that produces errors will interfere with the Sagnac phase shift, and the present invention can alleviate or eliminate this mechanism in the photonic integrated chip, which is specifically described as follows: First, this erroneous phase shift signal may Caused by, for example, the slight non-reciprocity of the Y branch in photonic integrated chips. The Y-branch works as a pair of waveguides placed at an angle relative to each other and can be viewed as a dual-mode waveguide near the junction. When the input light from the fundamental waveguide of the Y branch reaches the coupling region of the Y branch, the evanescent waves overlap in the dual-mode waveguide, and the fundamental symmetric mode is converted into a second-order antisymmetric mode, and the two lobes of the mode field are separated by separated and almost perfectly guided in the two branched waveguides. For the two return signals reaching the coupling region, a fundamental mode is formed and guided by the fundamental waveguide, while a second-order antisymmetric mode above the waveguide cutoff is radiated into the substrate. Light propagating through the junction in different directions suffers different losses (depending on the particular direction) due to the residual differential loss between the symmetric and antisymmetric modes, so due to the slight non-reciprocity at the Y branch, at the Y branch A parasitic phase shift will appear at the base port of . The cascaded integrated silicon-based polarizers placed at the fundamental waveguide of the interferometric Y-branch can keep the phases of the two beams propagating in opposite directions through the polarization-maintaining fiber ring, and no additional phase error will be generated at the junction . Second, light coupling from the working polarization mode to its quadrature mode can also have erroneous phase signals. Since the polarization-maintaining fiber ring and the waveguide on the photonic integrated chip each support two polarization modes, and the Sagnac interferometer provides two parallel optical paths, any light coupled into the undesired polarization mode may generate non-reciprocal parasitics path. Most cross-coupling points are in fiber coils, but cross-coupling can also occur at fiber-to-waveguide splices and within paths in photonic integrated chips (eg, at interferometric Y-branches). To prevent such non-reciprocal parasitic paths, cascaded integrated silicon-based polarizers are configured with considerably high polarization extinction ratios. The polarization cross-coupling at the interferometric Y-branch is negligible because the high birefringence of the waveguide provides excellent polarization preservation, and the main polarization coupling occurs at the junction of the polarization-maintaining fiber ring with the photonic integrated chip. In order to avoid generating wrong phase signals at the connection point, it is necessary to ensure that the length L3 of the third curved waveguide, the length L4 of the fourth curved waveguide, and the depolarization length LD of the waveguide satisfy the following relationship: |L3- _L4 |> L _D ; the calculation formula of the depolarization length L _D of the waveguide is: L _D =L _dc /Δn; where: L _dc is the decoherence length of the light source, and Δn is the birefringence difference of the waveguide.

In the cascade integrated silicon-based polarizer, the specific process of filtering by a single integrated silicon-based polarizer unit is as follows: the light beam propagates through the first straight waveguide section, the semi-circular arc waveguide section, and the second straight waveguide section in turn . During the propagation process, the TM mode in the beam is diffracted into free space, and the TE mode in the beam propagates through the first straight waveguide section, the semi-circular arc waveguide section, and the second straight waveguide section in turn, as follows: when the beam When passing through the first straight waveguide segment, the TM mode conducts in the first tapered waveguide, and enters the subwavelength grating B under the guidance of the first tapered waveguide, and is then diffracted by the subwavelength grating B to free space. At the same time, the TE mode is cut off in the first tapered waveguide and the second tapered waveguide, thus protecting the propagation of the TE mode in the core waveguide. According to the formal birefringence formula of the subwavelength grating B (the first formula is: n _o ² = f · n _Si ² +(1-f) · n _air ² ; the second formula is: 1 / n _e ² = f / n _Si ² +(1-f) / n _air ² ), it can be seen that for the integrated silicon-based polarizing unit, the effective refractive index of the TE mode in the subwavelength grating B can be approximated as _ne (extraordinary refractive index) , the effective refractive index of the TM mode is n _o (ordinary refractive index), so when the beam passes through the semi-circular arc waveguide segment, the semi-circular arc waveguide segment uses bending to form polarization-dependent loss that causes a great difference between the TE mode and the TM mode, The subwavelength grating B forms a strong confinement for the TE mode (and a weak confinement for the TM mode), so that the TM mode enters the subwavelength grating B, and is then diffracted into free space by the subwavelength grating B. In the above process, since the first graded tapered waveguide is set with a wide head and a narrow tail (the effective refractive index has a large head and a small tail), the reflection loss of the TM mode is extremely low. Since the duty cycle of each grating of the subwavelength grating B gradually decreases from the inside to the outside, the return loss of the TM mode during the diffraction process is extremely low. Since the width of the head end of the tapered waveguide is larger than the width of the first grating bar of the subwavelength grating B, the tapered waveguide has a very strong guiding ability for the TM mode.

Figure 10 shows the polarization extinction ratio (PER) and insertion loss (IL) simulation results of the cascaded integrated silicon-based polarizers. The polarization extinction ratio (PER) is defined by the following formula: PER=10lg(T _TEout /T _TMout ). Insertion Loss (IL) is defined by the following formula: IL=-10lg(T _TEout ). It can be seen from Figure 10 that the polarization extinction ratio of the cascade integrated silicon-based polarizer is 55.21dB at the wavelength of 1.53μm, and the insertion loss is 0.43dB; at the wavelength of 1.55μm, the polarization extinction ratio of the cascaded integrated silicon-based polarizer is The ratio is 47.96dB, and the insertion loss is 0.52dB.

The specific process of the interferometric Y-branch splitting is as follows: the light beam propagates through the main straight waveguide section, the tapered waveguide section, two transition straight waveguide sections (subwavelength grating A), and two arc waveguide sections in sequence. During propagation, the two transition straight waveguide segments can reduce the insertion loss of the interferometric Y-branch. According to the formula n ² _eff =f·n ² _Si +(1−f)·n ² _air (where: f represents the duty cycle of the grid bars of the subwavelength grating A, and n _eff represents the equivalent refraction of the subwavelength grating A (n _Si represents the refractive index of silicon, and n _air represents the refractive index of air), it can be seen that the subwavelength grating A can increase the equivalent refractive index of the coupling slit, thereby reducing the refraction between the coupling slit and the two arc waveguide segments Therefore, the TE mode in the beam propagates from the coupling slit to the two arc waveguide segments with extremely low coupling loss.

The specific process of the interferometric Y-branch combining light is as follows: the two beams propagate through two arc waveguide sections, two transition straight waveguide sections (subwavelength grating A), tapered waveguide section, and main straight waveguide section in turn. During propagation, the two transition straight waveguide segments can reduce the insertion loss of the interferometric Y-branch. According to the formula n ² _eff =f·n ² _Si +(1−f)·n ² _air (where: f represents the duty cycle of the grid bars of the subwavelength grating A, and n _eff represents the equivalent refraction of the subwavelength grating A (n _Si represents the refractive index of silicon, and n _air represents the refractive index of air), it can be seen that the subwavelength grating A can increase the equivalent refractive index of the coupling slit, thereby reducing the refraction between the coupling slit and the two arc waveguide segments Therefore, the TE mode in the beam propagates from the two arc waveguide segments to the coupling slit with extremely low coupling loss.

Figure 11 shows the insertion loss (IL) simulation results for the interferometric Y-branch. When splitting light, the insertion loss (IL) is defined by the formula IL=-10lg((P _out1 +P _out2 )/P _in ), that is, the sum of the output power is -10 times lg compared to the total input power. When combining light, the insertion loss (IL) is defined by the formula IL=-10lg(P _out /(P _in1 +P _in2 )), that is, the total output power is -10 times the sum of the input power. It can be seen from Fig. 11 that the insertion loss of the interferometric Y branch is 0.22dB at a wavelength of 1.53 μm; the insertion loss of the interferometric Y branch is 0.2 dB at a wavelength of 1.55 μm.

In addition, the use of end-face coupling between the four curved waveguides and the four fibers of the fiber array can greatly reduce the alignment loss of the four curved waveguides and the four fibers of the fiber array, so that the insertion loss of the four curved waveguides is lower than 0.5dB, so that the insertion loss of the present invention is lower than 3dB at both the wavelength of 1.53μm and the wavelength of 1.55μm.

Based on the above process, the photonic integrated chip for miniaturized interferometric fiber optic gyroscope described in the present invention is based on an SOI platform with high refractive contrast. Cascaded integrated silicon-based polarizer with low insertion loss, low processing difficulty, low processing cost, and compact size, on the other hand, by using the source Y branch with large bandwidth, uniform splitting power, low insertion loss, and low sensitivity to processing errors and the interferometric Y branch to replace the two couplers, spatial filters, and polarizers in the traditional interferometric fiber optic The gyroscope has the advantages of low insertion loss and low production cost.

The invention has reasonable structure and ingenious design, and effectively solves the problems that the traditional interferometric fiber optic gyroscope is difficult to achieve miniaturization, high insertion loss and high production cost.

Description of drawings

Figure 1 is a schematic structural diagram of the present invention.

2 is a schematic diagram of the first structure of the source Y branch, the interferometric Y branch, and the cascade integrated silicon-based polarizer in the present invention.

3 is a schematic diagram of the second structure of the source Y branch, the interferometric Y branch, and the cascade integrated silicon-based polarizer in the present invention.

4 is a schematic diagram of the third structure of the source Y branch, the interferometric Y branch, and the cascade integrated silicon-based polarizer in the present invention.

5 is a schematic diagram of the fourth structure of the source Y branch, the interferometric Y branch, and the cascade integrated silicon-based polarizer in the present invention.

6 is a schematic diagram of the fifth structure of the source Y branch, the interferometric Y branch, and the cascade integrated silicon-based polarizer in the present invention.

FIG. 7 is a schematic structural diagram of the integrated silicon-based Y-waveguide in the present invention.

FIG. 8 is a schematic structural diagram of an integrated silicon-based polarizing unit in the present invention.

FIG. 9 is a reference diagram of the use state of the present invention.

FIG. 10 is a graph showing the simulation results of the polarization extinction ratio (PER) and insertion loss (IL) of the cascading integrated silicon-based polarizer in the present invention.

FIG. 11 is a graph of the insertion loss (IL) simulation result of the interferometric Y branch in the present invention.

In the figure: 101-main straight waveguide segment, 102-conical waveguide segment, 103-transition straight waveguide segment, 104-arc waveguide segment, 105-grid bars of subwavelength grating A, 201-semi-circular-arc waveguide segment, 202 -Straight waveguide segment, 203-Gating bars of subwavelength grating B, 204-Tapered waveguide, 301-U-shaped waveguide A, 302-U-shaped waveguide B, 401-S-shaped waveguide A, 402-S-shaped waveguide B, 5-SOI platform, 6-bending waveguide, 7-fiber array, 8-photodetector, 9-light source, 10-polarization-maintaining fiber ring, 11-piezoceramic phase modulator; the dotted line represents the dividing line between the waveguide segments .

Detailed ways

Example 1

A photonic integrated chip for miniaturized interferometric fiber optic gyroscope, comprising an SOI platform 5, four curved waveguides 6, two integrated silicon-based Y-waveguides, and a cascaded integrated silicon-based polarizer;

Four curved waveguides 6 , two integrated silicon-based Y-waveguides, and cascaded integrated silicon-based polarizers are all processed based on the SOI platform 5 ;

The tail end surfaces of the four curved waveguides 6 are all flush with the right end surface of the SOI platform 5, and the length of the third curved waveguide 6 is not equal to the length of the fourth curved waveguide 6;

Each of the integrated silicon-based Y-waveguides includes a main straight waveguide section 101; the tail end of the main straight waveguide section 101 is extended with a tapered waveguide section 102 with a narrow head end and a wide tail end; the tail end of the tapered waveguide section 102 extends Two transition straight waveguide sections 103 are provided, and the two transition straight waveguide sections 103 are symmetrically distributed along the width direction of the main straight waveguide section 101; a coupling slit is formed between the two transition straight waveguide sections 103; the two transition straight waveguide sections A circular arc waveguide segment 104 is extended from the end of the segment 103, and the two circular arc waveguide segments 104 are symmetrically distributed along the width direction of the main straight waveguide segment 101; the coupling slit is filled with a subwavelength grating A, and the subwavelength The length direction of each grating 105 of the grating A is consistent with the width direction of the main straight waveguide segment 101; the thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition The thickness of the arc waveguide segment 104 and the thickness of the subwavelength grating A are the same; the width of the main straight waveguide segment 101, the head end width of the tapered waveguide segment 102, the width of the two transition straight waveguide segments 103, the width of the two arc waveguide segments The widths of the segments 104 are all the same; the width of the tail end of the tapered waveguide segment 102 is equal to the sum of the width of the two transition straight waveguide segments 103 and the width of the coupling slit;

The first integrated silicon-based Y-waveguide serves as the source Y-branch; the second integrated silicon-based Y-waveguide serves as the interferometric Y-branch; end connection; the tail end of the second arc waveguide segment of the source Y branch is connected to the head end of the second curved waveguide 6; the tail end of the first arc waveguide segment of the interferometric Y branch is connected to the third curved waveguide The head end of 6 is connected; the tail end of the second arc waveguide segment of the interferometric Y branch is connected with the head end of the fourth curved waveguide 6;

The cascaded integrated silicon-based polarizer includes N integrated silicon-based polarizing units; N is a positive integer, and 2≤N≤9;

Each of the integrated silicon-based polarizing units includes a core layer waveguide, a subwavelength grating B, and two tapered waveguides 204; Two straight waveguide segments 202 at both ends; each grid bar 203 of the subwavelength grating B is a semicircular arc grid bar, and the opening direction of the semicircular arc grid bar is consistent with the opening direction of the semicircular arc waveguide segment 201; the subwavelength grating The period of B is a fixed value; the duty cycle of each grid bar 203 of the subwavelength grating B gradually decreases from the inside to the outside; the first grid bar 203 of the subwavelength grating B is coupled parallel to the outside of the semicircular arc waveguide segment 201; The two graded tapered waveguides 204 are both arranged with a wide head and a narrow tail, and the head ends of the two graded tapered waveguides 204 are respectively butted with both ends of the first grid bar 203 of the subwavelength grating B; The shaped waveguides 204 are respectively coupled to the outside of the two straight waveguide segments 202 in parallel; the thickness of the semicircular arc waveguide segment 201, the thickness of the two straight waveguide segments 202, and the thickness of the subwavelength grating B are all the same; the two tapered waveguides 204 The thickness of the subwavelength grating B is larger than that of the subwavelength grating B; the width of the semicircular arc waveguide segment 201 and the width of the two straight waveguide segments 202 are the same; The width of one grid bar 203; the coupling spacing between the two tapered waveguides 204 and the two straight waveguide segments 202 is equal to the coupling spacing between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201;

The core layer waveguides of the first to Nth integrated silicon-based polarizing units are connected in series in sequence, and the head end of the main straight waveguide section 101 of the source Y branch passes through the core layer waveguides of the first to Nth integrated silicon-based polarizing units in sequence. It is connected with the head end of the main straight waveguide section 101 of the interferometric Y branch.

The thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition straight waveguide segments 103, the thickness of the two arc waveguide segments 104, and the thickness of the sub-wavelength grating A are all 190 nm to 250 nm; The length of the waveguide segment 102 is greater than or equal to 2 μm; the lengths of the two transition straight waveguide segments 103 are both 0.95 μm to 1.05 μm; the inner diameters of the two arcuate waveguide segments 104 are both greater than 5 μm; the period of the subwavelength grating A is 100 nm to 300 nm; The number of 105 bars of the subwavelength grating A is 4~6;

The period of the subwavelength grating B refers to the difference between the inner diameters of two adjacent grid bars 203 of the subwavelength grating B; the duty cycle of a grid bar 203 of the subwavelength grating B refers to the width of the grid bar 203 and the subwavelength The ratio of the period of the grating B;

The thickness of the semi-circular arc waveguide section 201 is 210 nm to 340 nm; the width of the semi-circular arc waveguide section 201 is 350 nm to 550 nm; the inner diameter of the semi-circular arc waveguide section 201 is less than 5 μm; the thicknesses of the two straight waveguide sections 202 are both 210 nm to 340 nm ; The widths of the two straight waveguide sections 202 are both 350nm~550nm;

The thickness of the subwavelength grating B is 210nm~340nm; the number of grid bars 203 of the subwavelength grating B is 2~15; the period of the subwavelength grating B is 200nm~350nm; The coupling spacing of the arc waveguide section 201 is 50nm~150nm; the maximum duty cycle of the subwavelength grating B is 0.55~0.75; the minimum duty cycle of the subwavelength grating B is 0.01~0.3;

The inner diameter R _i of the ith grating 203 of the subwavelength grating B satisfies the following formula:

R _i =R ₀ +W _wg +gap+Λ·(i-1);

In the formula: R ₀ represents the inner diameter of the semi-circular arc waveguide segment 201; W _wg represents the width of the semi-circular arc waveguide segment 201; gap represents the coupling distance between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201 ; Λ represents the period of the subwavelength grating B;

The duty cycle of each grid bar 203 of the subwavelength grating B is gradually and uniformly reduced from the inside to the outside, so as to ensure that the effective refractive index is gradually reduced uniformly from the inside to the outside; the minimum duty cycle of the subwavelength grating B is under the minimum line width allowed by processing set as small as possible;

The thicknesses of the two tapered waveguides 204 are both 300 nm to 450 nm; the widths of the first ends of the two tapered waveguides 204 are both 140 nm to 250 nm; the widths of the ends of the two tapered waveguides 204 are both less than 140 nm; The lengths of the tapered waveguides 204 are all greater than 2 μm and less than 20 μm; the coupling distances between the two tapered waveguides 204 and the two straight waveguide sections 202 are both 50 nm to 150 nm.

As shown in FIG. 2, in this embodiment, N is an odd number; the head end of the main straight waveguide section 101 of the source Y branch is directly connected to the core waveguide of the first integrated silicon-based polarizing unit; the Nth integrated The core waveguide of the silicon-based polarizing unit is directly connected to the head end of the main straight waveguide section 101 of the interferometric Y branch; the core waveguides of the first to Nth integrated silicon-based polarizing units are directly connected in series.

Embodiment 2

A photonic integrated chip for miniaturized interferometric fiber optic gyroscope, comprising an SOI platform 5, four curved waveguides 6, two integrated silicon-based Y-waveguides, and a cascaded integrated silicon-based polarizer;

Four curved waveguides 6 , two integrated silicon-based Y-waveguides, and cascaded integrated silicon-based polarizers are all processed based on the SOI platform 5 ;

The tail end surfaces of the four curved waveguides 6 are all flush with the right end surface of the SOI platform 5, and the length of the third curved waveguide 6 is not equal to the length of the fourth curved waveguide 6;

Each of the integrated silicon-based Y-waveguides includes a main straight waveguide section 101; the tail end of the main straight waveguide section 101 is extended with a tapered waveguide section 102 with a narrow head end and a wide tail end; the tail end of the tapered waveguide section 102 extends Two transition straight waveguide sections 103 are provided, and the two transition straight waveguide sections 103 are symmetrically distributed along the width direction of the main straight waveguide section 101; a coupling slit is formed between the two transition straight waveguide sections 103; the two transition straight waveguide sections A circular arc waveguide segment 104 is extended from the end of the segment 103, and the two circular arc waveguide segments 104 are symmetrically distributed along the width direction of the main straight waveguide segment 101; the coupling slit is filled with a subwavelength grating A, and the subwavelength The length direction of each grating 105 of the grating A is consistent with the width direction of the main straight waveguide segment 101; the thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition The thickness of the arc waveguide segment 104 and the thickness of the subwavelength grating A are the same; the width of the main straight waveguide segment 101, the head end width of the tapered waveguide segment 102, the width of the two transition straight waveguide segments 103, the width of the two arc waveguide segments The widths of the segments 104 are all the same; the width of the tail end of the tapered waveguide segment 102 is equal to the sum of the width of the two transition straight waveguide segments 103 and the width of the coupling slit;

The first integrated silicon-based Y-waveguide serves as the source Y-branch; the second integrated silicon-based Y-waveguide serves as the interferometric Y-branch; end connection; the tail end of the second arc waveguide segment of the source Y branch is connected to the head end of the second curved waveguide 6; the tail end of the first arc waveguide segment of the interferometric Y branch is connected to the third curved waveguide The head end of 6 is connected; the tail end of the second arc waveguide segment of the interferometric Y branch is connected with the head end of the fourth curved waveguide 6;

The cascaded integrated silicon-based polarizer includes N integrated silicon-based polarizing units; N is a positive integer, and 2≤N≤9;

Each of the integrated silicon-based polarizing units includes a core layer waveguide, a subwavelength grating B, and two tapered waveguides 204; Two straight waveguide segments 202 at both ends; each grid bar 203 of the subwavelength grating B is a semicircular arc grid bar, and the opening direction of the semicircular arc grid bar is consistent with the opening direction of the semicircular arc waveguide segment 201; the subwavelength grating The period of B is a fixed value; the duty cycle of each grid bar 203 of the subwavelength grating B gradually decreases from the inside to the outside; the first grid bar 203 of the subwavelength grating B is coupled parallel to the outside of the semicircular arc waveguide segment 201; The two graded tapered waveguides 204 are both arranged with a wide head and a narrow tail, and the head ends of the two graded tapered waveguides 204 are respectively butted with both ends of the first grid bar 203 of the subwavelength grating B; The shaped waveguides 204 are respectively coupled to the outside of the two straight waveguide segments 202 in parallel; the thickness of the semicircular arc waveguide segment 201, the thickness of the two straight waveguide segments 202, and the thickness of the subwavelength grating B are all the same; the two tapered waveguides 204 The thickness of the subwavelength grating B is larger than that of the subwavelength grating B; the width of the semicircular arc waveguide segment 201 and the width of the two straight waveguide segments 202 are the same; The width of one grid bar 203; the coupling spacing between the two tapered waveguides 204 and the two straight waveguide segments 202 is equal to the coupling spacing between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201;

The core layer waveguides of the first to Nth integrated silicon-based polarizing units are connected in series in sequence, and the head end of the main straight waveguide section 101 of the source Y branch passes through the core layer waveguides of the first to Nth integrated silicon-based polarizing units in sequence. It is connected with the head end of the main straight waveguide section 101 of the interferometric Y branch.

The thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition straight waveguide segments 103, the thickness of the two arc waveguide segments 104, and the thickness of the sub-wavelength grating A are all 190 nm to 250 nm; The length of the waveguide segment 102 is greater than or equal to 2 μm; the lengths of the two transition straight waveguide segments 103 are both 0.95 μm to 1.05 μm; the inner diameters of the two arcuate waveguide segments 104 are both greater than 5 μm; the period of the subwavelength grating A is 100 nm to 300 nm; The number of 105 bars of the subwavelength grating A is 4~6;

The period of the subwavelength grating B refers to the difference between the inner diameters of two adjacent grid bars 203 of the subwavelength grating B; the duty cycle of a grid bar 203 of the subwavelength grating B refers to the width of the grid bar 203 and the subwavelength The ratio of the period of the grating B;

The thickness of the semi-circular arc waveguide section 201 is 210 nm to 340 nm; the width of the semi-circular arc waveguide section 201 is 350 nm to 550 nm; the inner diameter of the semi-circular arc waveguide section 201 is less than 5 μm; the thicknesses of the two straight waveguide sections 202 are both 210 nm to 340 nm ; The widths of the two straight waveguide sections 202 are both 350nm~550nm;

The thickness of the subwavelength grating B is 210nm~340nm; the number of grid bars 203 of the subwavelength grating B is 2~15; the period of the subwavelength grating B is 200nm~350nm; The coupling spacing of the arc waveguide section 201 is 50nm~150nm; the maximum duty cycle of the subwavelength grating B is 0.55~0.75; the minimum duty cycle of the subwavelength grating B is 0.01~0.3;

The inner diameter R _i of the ith grating 203 of the subwavelength grating B satisfies the following formula:

R _i =R ₀ +W _wg +gap+Λ·(i-1);

In the formula: R ₀ represents the inner diameter of the semi-circular arc waveguide segment 201; W _wg represents the width of the semi-circular arc waveguide segment 201; gap represents the coupling distance between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201 ; Λ represents the period of the subwavelength grating B;

The duty cycle of each grid bar 203 of the subwavelength grating B is gradually and uniformly reduced from the inside to the outside, so as to ensure that the effective refractive index is gradually reduced uniformly from the inside to the outside; the minimum duty cycle of the subwavelength grating B is under the minimum line width allowed by processing set as small as possible;

The thicknesses of the two tapered waveguides 204 are both 300 nm to 450 nm; the widths of the first ends of the two tapered waveguides 204 are both 140 nm to 250 nm; the widths of the ends of the two tapered waveguides 204 are both less than 140 nm; The lengths of the tapered waveguides 204 are all greater than 2 μm and less than 20 μm; the coupling distances between the two tapered waveguides 204 and the two straight waveguide sections 202 are both 50 nm to 150 nm.

As shown in FIG. 3 , in this embodiment, N is an even number; the head end of the main straight waveguide section 101 of the source Y branch is directly connected to the core waveguide of the first integrated silicon-based polarizing unit; the Nth integrated The core waveguide of the silicon-based polarizing unit is directly connected to the head end of the main straight waveguide section 101 of the interferometric Y branch; the core waveguides of the first to Nth integrated silicon-based polarizing units are directly connected in series.

Embodiment 3

A photonic integrated chip for miniaturized interferometric fiber optic gyroscope, comprising an SOI platform 5, four curved waveguides 6, two integrated silicon-based Y-waveguides, and a cascaded integrated silicon-based polarizer;

Four curved waveguides 6 , two integrated silicon-based Y-waveguides, and cascaded integrated silicon-based polarizers are all processed based on the SOI platform 5 ;

The tail end surfaces of the four curved waveguides 6 are all flush with the right end surface of the SOI platform 5, and the length of the third curved waveguide 6 is not equal to the length of the fourth curved waveguide 6;

Each of the integrated silicon-based Y-waveguides includes a main straight waveguide section 101; the tail end of the main straight waveguide section 101 is extended with a tapered waveguide section 102 with a narrow head end and a wide tail end; the tail end of the tapered waveguide section 102 extends Two transition straight waveguide sections 103 are provided, and the two transition straight waveguide sections 103 are symmetrically distributed along the width direction of the main straight waveguide section 101; a coupling slit is formed between the two transition straight waveguide sections 103; the two transition straight waveguide sections A circular arc waveguide segment 104 is extended from the end of the segment 103, and the two circular arc waveguide segments 104 are symmetrically distributed along the width direction of the main straight waveguide segment 101; the coupling slit is filled with a subwavelength grating A, and the subwavelength The length direction of each grating 105 of the grating A is consistent with the width direction of the main straight waveguide segment 101; the thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition The thickness of the arc waveguide segment 104 and the thickness of the subwavelength grating A are the same; the width of the main straight waveguide segment 101, the head end width of the tapered waveguide segment 102, the width of the two transition straight waveguide segments 103, the width of the two arc waveguide segments The widths of the segments 104 are all the same; the width of the tail end of the tapered waveguide segment 102 is equal to the sum of the width of the two transition straight waveguide segments 103 and the width of the coupling slit;

The first integrated silicon-based Y-waveguide serves as the source Y-branch; the second integrated silicon-based Y-waveguide serves as the interferometric Y-branch; end connection; the tail end of the second arc waveguide segment of the source Y branch is connected to the head end of the second curved waveguide 6; the tail end of the first arc waveguide segment of the interferometric Y branch is connected to the third curved waveguide The head end of 6 is connected; the tail end of the second arc waveguide segment of the interferometric Y branch is connected with the head end of the fourth curved waveguide 6;

The cascaded integrated silicon-based polarizer includes N integrated silicon-based polarizing units; N is a positive integer, and 2≤N≤9;

Each of the integrated silicon-based polarizing units includes a core layer waveguide, a subwavelength grating B, and two tapered waveguides 204; Two straight waveguide segments 202 at both ends; each grid bar 203 of the subwavelength grating B is a semicircular arc grid bar, and the opening direction of the semicircular arc grid bar is consistent with the opening direction of the semicircular arc waveguide segment 201; the subwavelength grating The period of B is a fixed value; the duty cycle of each grid bar 203 of the subwavelength grating B gradually decreases from the inside to the outside; the first grid bar 203 of the subwavelength grating B is coupled parallel to the outside of the semicircular arc waveguide segment 201; The two graded tapered waveguides 204 are both arranged with a wide head and a narrow tail, and the head ends of the two graded tapered waveguides 204 are respectively butted with both ends of the first grid bar 203 of the subwavelength grating B; The shaped waveguides 204 are respectively coupled to the outside of the two straight waveguide segments 202 in parallel; the thickness of the semicircular arc waveguide segment 201, the thickness of the two straight waveguide segments 202, and the thickness of the subwavelength grating B are all the same; the two tapered waveguides 204 The thickness of the subwavelength grating B is larger than that of the subwavelength grating B; the width of the semicircular arc waveguide segment 201 and the width of the two straight waveguide segments 202 are the same; The width of one grid bar 203; the coupling spacing between the two tapered waveguides 204 and the two straight waveguide segments 202 is equal to the coupling spacing between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201;

The core layer waveguides of the first to Nth integrated silicon-based polarizing units are connected in series in sequence, and the head end of the main straight waveguide section 101 of the source Y branch passes through the core layer waveguides of the first to Nth integrated silicon-based polarizing units in sequence. It is connected with the head end of the main straight waveguide section 101 of the interferometric Y branch.

The thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition straight waveguide segments 103, the thickness of the two arc waveguide segments 104, and the thickness of the sub-wavelength grating A are all 190 nm to 250 nm; The length of the waveguide segment 102 is greater than or equal to 2 μm; the lengths of the two transition straight waveguide segments 103 are both 0.95 μm to 1.05 μm; the inner diameters of the two arcuate waveguide segments 104 are both greater than 5 μm; the period of the subwavelength grating A is 100 nm to 300 nm; The number of 105 bars of the subwavelength grating A is 4~6;

The period of the subwavelength grating B refers to the difference between the inner diameters of two adjacent grid bars 203 of the subwavelength grating B; the duty cycle of a grid bar 203 of the subwavelength grating B refers to the width of the grid bar 203 and the subwavelength The ratio of the period of the grating B;

The thickness of the semi-circular arc waveguide section 201 is 210 nm to 340 nm; the width of the semi-circular arc waveguide section 201 is 350 nm to 550 nm; the inner diameter of the semi-circular arc waveguide section 201 is less than 5 μm; the thicknesses of the two straight waveguide sections 202 are both 210 nm to 340 nm ; The widths of the two straight waveguide sections 202 are both 350nm~550nm;

The thickness of the subwavelength grating B is 210nm~340nm; the number of grid bars 203 of the subwavelength grating B is 2~15; the period of the subwavelength grating B is 200nm~350nm; The coupling spacing of the arc waveguide section 201 is 50nm~150nm; the maximum duty cycle of the subwavelength grating B is 0.55~0.75; the minimum duty cycle of the subwavelength grating B is 0.01~0.3;

The inner diameter R _i of the ith grating 203 of the subwavelength grating B satisfies the following formula:

R _i =R ₀ +W _wg +gap+Λ·(i-1);

In the formula: R ₀ represents the inner diameter of the semi-circular arc waveguide segment 201; W _wg represents the width of the semi-circular arc waveguide segment 201; gap represents the coupling distance between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201 ; Λ represents the period of the subwavelength grating B;

The duty cycle of each grid bar 203 of the subwavelength grating B is gradually and uniformly reduced from the inside to the outside, so as to ensure that the effective refractive index is gradually reduced uniformly from the inside to the outside; the minimum duty cycle of the subwavelength grating B is under the minimum line width allowed by processing set as small as possible;

The thicknesses of the two tapered waveguides 204 are both 300 nm to 450 nm; the widths of the first ends of the two tapered waveguides 204 are both 140 nm to 250 nm; the widths of the ends of the two tapered waveguides 204 are both less than 140 nm; The lengths of the tapered waveguides 204 are all greater than 2 μm and less than 20 μm; the coupling distances between the two tapered waveguides 204 and the two straight waveguide sections 202 are both 50 nm to 150 nm.

As shown in FIG. 4 , in this embodiment, the cascaded integrated silicon-based polarizer further includes a U-shaped waveguide A301; N is an even number; the head end of the main straight waveguide section 101 of the source Y branch is connected to the first The core layer waveguide of the integrated silicon-based polarizing unit is directly connected; the core layer waveguide of the N-th integrated silicon-based polarizing unit is connected to the head end of the main straight waveguide section 101 of the interferometric Y branch through the U-shaped waveguide A301; The series connection mode of the core layer waveguides of the first to Nth integrated silicon-based polarizing units is direct series connection.

Embodiment 4

A photonic integrated chip for miniaturized interferometric fiber optic gyroscope, comprising an SOI platform 5, four curved waveguides 6, two integrated silicon-based Y-waveguides, and a cascaded integrated silicon-based polarizer;

Four curved waveguides 6 , two integrated silicon-based Y-waveguides, and cascaded integrated silicon-based polarizers are all processed based on the SOI platform 5 ;

The tail end surfaces of the four curved waveguides 6 are all flush with the right end surface of the SOI platform 5, and the length of the third curved waveguide 6 is not equal to the length of the fourth curved waveguide 6;

Each of the integrated silicon-based Y-waveguides includes a main straight waveguide section 101; the tail end of the main straight waveguide section 101 is extended with a tapered waveguide section 102 with a narrow head end and a wide tail end; the tail end of the tapered waveguide section 102 extends Two transition straight waveguide sections 103 are provided, and the two transition straight waveguide sections 103 are symmetrically distributed along the width direction of the main straight waveguide section 101; a coupling slit is formed between the two transition straight waveguide sections 103; the two transition straight waveguide sections A circular arc waveguide segment 104 is extended from the end of the segment 103, and the two circular arc waveguide segments 104 are symmetrically distributed along the width direction of the main straight waveguide segment 101; the coupling slit is filled with a subwavelength grating A, and the subwavelength The length direction of each grating 105 of the grating A is consistent with the width direction of the main straight waveguide segment 101; the thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition The thickness of the arc waveguide segment 104 and the thickness of the subwavelength grating A are the same; the width of the main straight waveguide segment 101, the head end width of the tapered waveguide segment 102, the width of the two transition straight waveguide segments 103, the width of the two arc waveguide segments The widths of the segments 104 are all the same; the width of the tail end of the tapered waveguide segment 102 is equal to the sum of the width of the two transition straight waveguide segments 103 and the width of the coupling slit;

The first integrated silicon-based Y-waveguide serves as the source Y-branch; the second integrated silicon-based Y-waveguide serves as the interferometric Y-branch; end connection; the tail end of the second arc waveguide segment of the source Y branch is connected to the head end of the second curved waveguide 6; the tail end of the first arc waveguide segment of the interferometric Y branch is connected to the third curved waveguide The head end of 6 is connected; the tail end of the second arc waveguide segment of the interferometric Y branch is connected with the head end of the fourth curved waveguide 6;

The cascaded integrated silicon-based polarizer includes N integrated silicon-based polarizing units; N is a positive integer, and 2≤N≤9;

Each of the integrated silicon-based polarizing units includes a core layer waveguide, a subwavelength grating B, and two tapered waveguides 204; Two straight waveguide segments 202 at both ends; each grid bar 203 of the subwavelength grating B is a semicircular arc grid bar, and the opening direction of the semicircular arc grid bar is consistent with the opening direction of the semicircular arc waveguide segment 201; the subwavelength grating The period of B is a fixed value; the duty cycle of each grid bar 203 of the subwavelength grating B gradually decreases from the inside to the outside; the first grid bar 203 of the subwavelength grating B is coupled parallel to the outside of the semicircular arc waveguide segment 201; The two graded tapered waveguides 204 are both arranged with a wide head and a narrow tail, and the head ends of the two graded tapered waveguides 204 are respectively butted with both ends of the first grid bar 203 of the subwavelength grating B; The shaped waveguides 204 are respectively coupled to the outside of the two straight waveguide segments 202 in parallel; the thickness of the semicircular arc waveguide segment 201, the thickness of the two straight waveguide segments 202, and the thickness of the subwavelength grating B are all the same; the two tapered waveguides 204 The thickness of the subwavelength grating B is larger than that of the subwavelength grating B; the width of the semicircular arc waveguide segment 201 and the width of the two straight waveguide segments 202 are the same; The width of one grid bar 203; the coupling spacing between the two tapered waveguides 204 and the two straight waveguide segments 202 is equal to the coupling spacing between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201;

The core layer waveguides of the first to Nth integrated silicon-based polarizing units are connected in series in sequence, and the head end of the main straight waveguide section 101 of the source Y branch passes through the core layer waveguides of the first to Nth integrated silicon-based polarizing units in sequence. It is connected with the head end of the main straight waveguide section 101 of the interferometric Y branch.

The thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition straight waveguide segments 103, the thickness of the two arc waveguide segments 104, and the thickness of the sub-wavelength grating A are all 190 nm to 250 nm; The length of the waveguide segment 102 is greater than or equal to 2 μm; the lengths of the two transition straight waveguide segments 103 are both 0.95 μm to 1.05 μm; the inner diameters of the two arcuate waveguide segments 104 are both greater than 5 μm; the period of the subwavelength grating A is 100 nm to 300 nm; The number of 105 bars of the subwavelength grating A is 4~6;

The period of the subwavelength grating B refers to the difference between the inner diameters of two adjacent grid bars 203 of the subwavelength grating B; the duty cycle of a grid bar 203 of the subwavelength grating B refers to the width of the grid bar 203 and the subwavelength The ratio of the period of the grating B;

The thickness of the semi-circular arc waveguide section 201 is 210 nm to 340 nm; the width of the semi-circular arc waveguide section 201 is 350 nm to 550 nm; the inner diameter of the semi-circular arc waveguide section 201 is less than 5 μm; the thicknesses of the two straight waveguide sections 202 are both 210 nm to 340 nm ; The widths of the two straight waveguide sections 202 are both 350nm~550nm;

The thickness of the subwavelength grating B is 210nm~340nm; the number of grid bars 203 of the subwavelength grating B is 2~15; the period of the subwavelength grating B is 200nm~350nm; The coupling spacing of the arc waveguide section 201 is 50nm~150nm; the maximum duty cycle of the subwavelength grating B is 0.55~0.75; the minimum duty cycle of the subwavelength grating B is 0.01~0.3;

The inner diameter R _i of the ith grating 203 of the subwavelength grating B satisfies the following formula:

R _i =R ₀ +W _wg +gap+Λ·(i-1);

In the formula: R ₀ represents the inner diameter of the semi-circular arc waveguide segment 201; W _wg represents the width of the semi-circular arc waveguide segment 201; gap represents the coupling distance between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201 ; Λ represents the period of the subwavelength grating B;

The duty cycle of each grid bar 203 of the subwavelength grating B is gradually and uniformly reduced from the inside to the outside, so as to ensure that the effective refractive index is gradually reduced uniformly from the inside to the outside; the minimum duty cycle of the subwavelength grating B is under the minimum line width allowed by processing set as small as possible;

The thicknesses of the two tapered waveguides 204 are both 300 nm to 450 nm; the widths of the first ends of the two tapered waveguides 204 are both 140 nm to 250 nm; the widths of the ends of the two tapered waveguides 204 are both less than 140 nm; The lengths of the tapered waveguides 204 are all greater than 2 μm and less than 20 μm; the coupling distances between the two tapered waveguides 204 and the two straight waveguide sections 202 are both 50 nm to 150 nm.

As shown in FIG. 5 , in this embodiment, the cascaded integrated silicon-based polarizer further includes an S-shaped waveguide A401; N is an even number; the head end of the main straight waveguide section 101 of the source Y branch and the first The core layer waveguide of the integrated silicon-based polarizer unit is directly connected; the core layer waveguide of the Nth integrated silicon-based polarizer unit is directly connected to the head end of the main straight waveguide section 101 of the interferometric Y branch; the N/2th The core layer waveguide of the integrated silicon-based polarizing unit and the N/2+1 th core layer waveguide of the integrated silicon-based polarizing unit are connected through an S-shaped waveguide A401.

Embodiment 5

A photonic integrated chip for miniaturized interferometric fiber optic gyroscope, comprising an SOI platform 5, four curved waveguides 6, two integrated silicon-based Y-waveguides, and a cascaded integrated silicon-based polarizer;

Four curved waveguides 6 , two integrated silicon-based Y-waveguides, and cascaded integrated silicon-based polarizers are all processed based on the SOI platform 5 ;

The tail end surfaces of the four curved waveguides 6 are all flush with the right end surface of the SOI platform 5, and the length of the third curved waveguide 6 is not equal to the length of the fourth curved waveguide 6;

Each of the integrated silicon-based Y-waveguides includes a main straight waveguide section 101; the tail end of the main straight waveguide section 101 is extended with a tapered waveguide section 102 with a narrow head end and a wide tail end; the tail end of the tapered waveguide section 102 extends Two transition straight waveguide sections 103 are provided, and the two transition straight waveguide sections 103 are symmetrically distributed along the width direction of the main straight waveguide section 101; a coupling slit is formed between the two transition straight waveguide sections 103; the two transition straight waveguide sections A circular arc waveguide segment 104 is extended from the end of the segment 103, and the two circular arc waveguide segments 104 are symmetrically distributed along the width direction of the main straight waveguide segment 101; the coupling slit is filled with a subwavelength grating A, and the subwavelength The length direction of each grating 105 of the grating A is consistent with the width direction of the main straight waveguide segment 101; the thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition The thickness of the arc waveguide segment 104 and the thickness of the subwavelength grating A are the same; the width of the main straight waveguide segment 101, the head end width of the tapered waveguide segment 102, the width of the two transition straight waveguide segments 103, the width of the two arc waveguide segments The widths of the segments 104 are all the same; the width of the tail end of the tapered waveguide segment 102 is equal to the sum of the width of the two transition straight waveguide segments 103 and the width of the coupling slit;

The first integrated silicon-based Y-waveguide serves as the source Y-branch; the second integrated silicon-based Y-waveguide serves as the interferometric Y-branch; end connection; the tail end of the second arc waveguide segment of the source Y branch is connected to the head end of the second curved waveguide 6; the tail end of the first arc waveguide segment of the interferometric Y branch is connected to the third curved waveguide The head end of 6 is connected; the tail end of the second arc waveguide segment of the interferometric Y branch is connected with the head end of the fourth curved waveguide 6;

The cascaded integrated silicon-based polarizer includes N integrated silicon-based polarizing units; N is a positive integer, and 2≤N≤9;

Each of the integrated silicon-based polarizing units includes a core layer waveguide, a subwavelength grating B, and two tapered waveguides 204; Two straight waveguide segments 202 at both ends; each grid bar 203 of the subwavelength grating B is a semicircular arc grid bar, and the opening direction of the semicircular arc grid bar is consistent with the opening direction of the semicircular arc waveguide segment 201; the subwavelength grating The period of B is a fixed value; the duty cycle of each grid bar 203 of the subwavelength grating B gradually decreases from the inside to the outside; the first grid bar 203 of the subwavelength grating B is coupled parallel to the outside of the semicircular arc waveguide segment 201; The two graded tapered waveguides 204 are both arranged with a wide head and a narrow tail, and the head ends of the two graded tapered waveguides 204 are respectively butted with both ends of the first grid bar 203 of the subwavelength grating B; The shaped waveguides 204 are respectively coupled to the outside of the two straight waveguide segments 202 in parallel; the thickness of the semicircular arc waveguide segment 201, the thickness of the two straight waveguide segments 202, and the thickness of the subwavelength grating B are all the same; the two tapered waveguides 204 The thickness of the subwavelength grating B is larger than that of the subwavelength grating B; the width of the semicircular arc waveguide segment 201 and the width of the two straight waveguide segments 202 are the same; The width of one grid bar 203; the coupling spacing between the two tapered waveguides 204 and the two straight waveguide segments 202 is equal to the coupling spacing between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201;

The core layer waveguides of the first to Nth integrated silicon-based polarizing units are connected in series in sequence, and the head end of the main straight waveguide section 101 of the source Y branch passes through the core layer waveguides of the first to Nth integrated silicon-based polarizing units in sequence. It is connected with the head end of the main straight waveguide section 101 of the interferometric Y branch.

The thickness of the main straight waveguide segment 101, the thickness of the tapered waveguide segment 102, the thickness of the two transition straight waveguide segments 103, the thickness of the two arc waveguide segments 104, and the thickness of the sub-wavelength grating A are all 190 nm to 250 nm; The length of the waveguide segment 102 is greater than or equal to 2 μm; the lengths of the two transition straight waveguide segments 103 are both 0.95 μm to 1.05 μm; the inner diameters of the two arcuate waveguide segments 104 are both greater than 5 μm; the period of the subwavelength grating A is 100 nm to 300 nm; The number of 105 bars of the subwavelength grating A is 4~6;

The period of the subwavelength grating B refers to the difference between the inner diameters of two adjacent grid bars 203 of the subwavelength grating B; the duty cycle of a grid bar 203 of the subwavelength grating B refers to the width of the grid bar 203 and the subwavelength The ratio of the period of the grating B;

The thickness of the semi-circular arc waveguide section 201 is 210 nm to 340 nm; the width of the semi-circular arc waveguide section 201 is 350 nm to 550 nm; the inner diameter of the semi-circular arc waveguide section 201 is less than 5 μm; the thicknesses of the two straight waveguide sections 202 are both 210 nm to 340 nm ; The widths of the two straight waveguide sections 202 are both 350nm~550nm;

The thickness of the subwavelength grating B is 210nm~340nm; the number of grid bars 203 of the subwavelength grating B is 2~15; the period of the subwavelength grating B is 200nm~350nm; The coupling spacing of the arc waveguide section 201 is 50nm~150nm; the maximum duty cycle of the subwavelength grating B is 0.55~0.75; the minimum duty cycle of the subwavelength grating B is 0.01~0.3;

The inner diameter R _i of the ith grating 203 of the subwavelength grating B satisfies the following formula:

R _i =R ₀ +W _wg +gap+Λ·(i-1);

In the formula: R ₀ represents the inner diameter of the semi-circular arc waveguide segment 201; W _wg represents the width of the semi-circular arc waveguide segment 201; gap represents the coupling distance between the first grid bar 203 of the subwavelength grating B and the semi-circular arc waveguide segment 201 ; Λ represents the period of the subwavelength grating B;

The duty cycle of each grid bar 203 of the subwavelength grating B is gradually and uniformly reduced from the inside to the outside, so as to ensure that the effective refractive index is gradually reduced uniformly from the inside to the outside; the minimum duty cycle of the subwavelength grating B is under the minimum line width allowed by processing set as small as possible;

The thicknesses of the two tapered waveguides 204 are both 300 nm to 450 nm; the widths of the first ends of the two tapered waveguides 204 are both 140 nm to 250 nm; the widths of the ends of the two tapered waveguides 204 are both less than 140 nm; The lengths of the tapered waveguides 204 are all greater than 2 μm and less than 20 μm; the coupling distances between the two tapered waveguides 204 and the two straight waveguide sections 202 are both 50 nm to 150 nm.

As shown in FIG. 6 , in this embodiment, the cascaded integrated silicon-based polarizer further includes a U-shaped waveguide B302 and an S-shaped waveguide B402; N is an even number; the head of the main straight waveguide section 101 of the source Y branch The end is directly connected to the core waveguide of the first integrated silicon-based polarizing unit; the core waveguide of the N-th integrated silicon-based polarizing unit and the head end of the main straight waveguide section 101 of the interferometric Y branch pass through U The S-shaped waveguide B402 is connected between the core layer waveguide of the N/2th integrated silicon-based polarizer unit and the N/2+1th core layer waveguide of the integrated silicon-based polarizer unit.

Although specific embodiments of the present invention have been described above, those skilled in the art will understand that these are merely illustrative and the scope of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principle and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims (7)

1. A photonic integrated chip for a miniaturized interferometric fiber optic gyroscope, comprising: the device comprises an SOI platform (5), four bent waveguides (6), two integrated silicon-based Y waveguides and a cascade integrated silicon-based polarizer;

four bending waveguides (6), two integrated silicon-based Y waveguides and a cascading integrated silicon-based polarizer are all processed on the basis of an SOI platform (5);

the tail end surfaces of the four bent waveguides (6) are flush with the right end surface of the SOI platform (5), and the length of the third bent waveguide (6) is not equal to that of the fourth bent waveguide (6);

each integrated silicon-based Y waveguide comprises a main straight waveguide section (101); a tapered waveguide section (102) with a narrow head end and a wide tail end is arranged at the tail end of the main straight waveguide section (101) in an extending manner; the tail end of the conical waveguide section (102) is provided with two transitional straight waveguide sections (103) in an extending mode, and the two transitional straight waveguide sections (103) are symmetrically distributed along the width direction of the main straight waveguide section (101); a coupling slit is formed between the two transition straight waveguide sections (103); the tail ends of the two transitional straight waveguide sections (103) are respectively provided with an arc waveguide section (104) in an extending way, and the two arc waveguide sections (104) are symmetrically distributed along the width direction of the main straight waveguide section (101); the coupling slit is filled with a sub-wavelength grating A, and the length direction of each grid bar (105) of the sub-wavelength grating A is consistent with the width direction of the main straight waveguide section (101); the thickness of the main straight waveguide section (101), the thickness of the conical waveguide section (102), the thickness of the two transition straight waveguide sections (103), the thickness of the two circular arc waveguide sections (104) and the thickness of the sub-wavelength grating A are all consistent; the width of the main straight waveguide section (101), the width of the head end of the conical waveguide section (102), the width of the two transition straight waveguide sections (103) and the width of the two arc waveguide sections (104) are all consistent; the width of the tail end of the conical waveguide section (102) is equal to the sum of the widths of the two transitional straight waveguide sections (103) and the width of the coupling slit;

a first integrated silicon-based Y waveguide as a source Y branch; a second integrated silicon-based Y waveguide as an interferometric Y-branch; the tail end of a first arc waveguide segment of the source Y branch is connected with the head end of a first curved waveguide (6); the tail end of a second arc waveguide section of the source Y branch is connected with the head end of a second curved waveguide (6); the tail end of the first arc waveguide segment of the interference type Y branch is connected with the head end of the third bent waveguide (6); the tail end of a second arc waveguide section of the interference type Y branch is connected with the head end of a fourth curved waveguide (6);

the cascade integrated silicon-based polarizer comprises N integrated silicon-based polarizing units; n is a positive integer and is more than or equal to 2 and less than or equal to 9;

each integrated silicon-based polarization unit comprises a core layer waveguide, a sub-wavelength grating B and two gradually-changed tapered waveguides (204); the core layer waveguide comprises a semi-circular arc waveguide section (201) and two straight waveguide sections (202) which are respectively arranged at two ends of the semi-circular arc waveguide section (201) in an extending mode; each grid bar (203) of the sub-wavelength grating B is a semi-circular arc grid bar, and the opening direction of the semi-circular arc grid bar is consistent with the opening direction of the semi-circular arc waveguide section (201); the period of the sub-wavelength grating B is a fixed value; the duty ratio of each grid bar (203) of the sub-wavelength grating B is gradually reduced from inside to outside; the first grating (203) of the sub-wavelength grating B is coupled to the outer side of the semi-arc waveguide section (201) in parallel; the two tapered waveguides (204) are arranged in a manner that the head ends are wide and the tail ends are narrow, and the head ends of the two tapered waveguides (204) are respectively butted with the two ends of the first grid bar (203) of the sub-wavelength grating B; the two tapered waveguides (204) are respectively coupled to the outer sides of the two straight waveguide sections (202) in parallel; the thickness of the semi-circular arc waveguide section (201), the thickness of the two straight waveguide sections (202) and the thickness of the sub-wavelength grating B are all consistent; the thicknesses of the two gradually-changed conical waveguides (204) are larger than that of the sub-wavelength grating B; the width of the semi-circular arc waveguide segment (201) and the width of the two straight waveguide segments (202) are consistent; the widths of the head ends of the two tapered waveguides (204) are larger than the width of the first grid strip (203) of the sub-wavelength grating B; the coupling distance between the two tapered waveguides (204) and the two straight waveguide sections (202) is equal to the coupling distance between the first grating strip (203) of the sub-wavelength grating B and the semi-arc waveguide section (201);

the core layer waveguides of the first to Nth integrated silicon-based polarization units are sequentially connected in series, and the head end of the main straight waveguide section (101) of the source Y branch is connected with the head end of the main straight waveguide section (101) of the interference type Y branch sequentially through the core layer waveguides of the first to Nth integrated silicon-based polarization units.

2. A photonic integrated chip for a miniaturized interferometric fiber optic gyroscope according to claim 1, characterized in that: the thickness of the main straight waveguide section (101), the thickness of the conical waveguide section (102), the thickness of the two transition straight waveguide sections (103), the thickness of the two arc waveguide sections (104) and the thickness of the sub-wavelength grating A are 190 nm-250 nm; the length of the tapered waveguide section (102) is greater than or equal to 2 μm; the lengths of the two transitional straight waveguide sections (103) are both 0.95-1.05 μm; the inner diameters of the two arc waveguide sections (104) are both larger than 5 mu m; the period of the sub-wavelength grating A is 100 nm-300 nm; the number of the grid bars (105) of the sub-wavelength grating A is 4-6;

the period of the sub-wavelength grating B refers to the difference of the inner diameters of two adjacent grating bars (203) of the sub-wavelength grating B; the duty ratio of a certain grid bar (203) of the sub-wavelength grating B refers to the ratio of the width of the grid bar (203) to the period of the sub-wavelength grating B;

the thickness of the semi-circular arc waveguide section (201) is 210 nm-340 nm; the width of the semicircular arc waveguide section (201) is 350-550 nm; the inner diameter of the semi-circular arc waveguide section (201) is less than 5 mu m; the thicknesses of the two straight waveguide sections (202) are 210 nm-340 nm; the width of each of the two straight waveguide sections (202) is 350-550 nm;

the thickness of the sub-wavelength grating B is 210 nm-340 nm; the number of the grid bars (203) of the sub-wavelength grating B is 2-15; the period of the sub-wavelength grating B is 200 nm-350 nm; the coupling distance between the first grating strip (203) of the sub-wavelength grating B and the semi-arc waveguide section (201) is 50 nm-150 nm; the maximum duty ratio of the sub-wavelength grating B is 0.55-0.75; the minimum duty ratio of the sub-wavelength grating B is 0.01-0.3;

inner diameter R of i-th grating strip (203) of sub-wavelength grating B_iThe following formula is satisfied:

R_i=R₀+W_wg+gap+Λ·(i-1)；

in the formula: r₀Represents the inner diameter of a semi-circular arc waveguide segment (201); w_wgRepresenting the width of the semi-circular waveguide segment (201); gap denotes the first of the sub-wavelength gratings BThe coupling distance between the grid bars (203) and the semi-circular arc waveguide section (201); Λ represents the period of the sub-wavelength grating B;

the duty ratio of each grid bar (203) of the sub-wavelength grating B is gradually and uniformly reduced from inside to outside so as to ensure that the effective refractive index is gradually and uniformly reduced from inside to outside; the minimum duty cycle of the sub-wavelength grating B is set as small as possible under the minimum allowable line width for processing;

the thicknesses of the two gradually-changed conical waveguides (204) are both 300 nm-450 nm; the widths of the head ends of the two tapered waveguides (204) are both 140 nm-250 nm; the width of the tail ends of the two tapered waveguides (204) is less than 140 nm; the lengths of the two tapered waveguides (204) are both greater than 2 μm and less than 20 μm; the coupling distance between the two tapered waveguide sections (204) and the two straight waveguide sections (202) is 50 nm-150 nm.

3. A photonic integrated chip for a miniaturized interferometric fiber optic gyroscope according to claim 1 or 2, characterized in that: n is an odd number; the head end of a main straight waveguide section (101) of a source Y branch is directly connected with a core layer waveguide of a first integrated silicon-based polarization unit; the core layer waveguide of the Nth integrated silicon-based polarization unit is directly connected with the head end of the main straight waveguide section (101) of the interference type Y branch; the core layer waveguides of the first to Nth integrated silicon-based polarization units are directly connected in series.

4. A photonic integrated chip for a miniaturized interferometric fiber optic gyroscope according to claim 1 or 2, characterized in that: n is an even number; the head end of a main straight waveguide section (101) of a source Y branch is directly connected with a core layer waveguide of a first integrated silicon-based polarization unit; the core layer waveguide of the Nth integrated silicon-based polarization unit is directly connected with the head end of the main straight waveguide section (101) of the interference type Y branch; the core layer waveguides of the first to Nth integrated silicon-based polarization units are directly connected in series.

5. A photonic integrated chip for a miniaturized interferometric fiber optic gyroscope according to claim 1 or 2, characterized in that: the cascade type integrated silicon-based polarizer further comprises a U-shaped waveguide A (301); n is an even number; the head end of a main straight waveguide section (101) of a source Y branch is directly connected with a core layer waveguide of a first integrated silicon-based polarization unit; the core layer waveguide of the Nth integrated silicon-based polarization unit is connected with the head end of the main straight waveguide section (101) of the interference type Y branch through a U-shaped waveguide A (301); the core layer waveguides of the first to Nth integrated silicon-based polarization units are directly connected in series.

6. A photonic integrated chip for a miniaturized interferometric fiber optic gyroscope according to claim 1 or 2, characterized in that: the cascade type integrated silicon-based polarizer further comprises an S-shaped waveguide A (401); n is an even number; the head end of a main straight waveguide section (101) of a source Y branch is directly connected with a core layer waveguide of a first integrated silicon-based polarization unit; the core layer waveguide of the Nth integrated silicon-based polarization unit is directly connected with the head end of the main straight waveguide section (101) of the interference type Y branch; the core layer waveguide of the N/2 th integrated silicon-based polarization unit is connected with the core layer waveguide of the N/2+1 th integrated silicon-based polarization unit through an S-shaped waveguide A (401).

7. A photonic integrated chip for a miniaturized interferometric fiber optic gyroscope according to claim 1 or 2, characterized in that: the cascade type integrated silicon-based polarizer further comprises a U-shaped waveguide B (302) and an S-shaped waveguide B (402); n is an even number; the head end of a main straight waveguide section (101) of a source Y branch is directly connected with a core layer waveguide of a first integrated silicon-based polarization unit; the core layer waveguide of the Nth integrated silicon-based polarization unit is connected with the head end of the main straight waveguide section (101) of the interference type Y branch through a U-shaped waveguide B (302); the core layer waveguide of the N/2 th integrated silicon-based polarization unit is connected with the core layer waveguide of the N/2+1 th integrated silicon-based polarization unit through an S-shaped waveguide B (402).

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