CN113204132A

CN113204132A - End face coupler and preparation method thereof

Info

Publication number: CN113204132A
Application number: CN202110493000.XA
Authority: CN
Inventors: 张燕; 刘思旸; 冯俊波
Original assignee: United Microelectronics Center Co Ltd
Current assignee: United Microelectronics Center Co Ltd
Priority date: 2021-05-07
Filing date: 2021-05-07
Publication date: 2021-08-03
Anticipated expiration: 2041-05-07
Also published as: CN113204132B

Abstract

The invention provides an end face coupler, which comprises a first coupling area, a phase shift area and a second coupling area, wherein the first coupling area, the phase shift area and the second coupling area are sequentially arranged along the direction of an output light field of a light source; the first coupling region comprises a beam splitting structure, divides an output light field of the light source into at least two first light fields and is fully coupled into the phase shifting region; the light field in the phase shift region is marked as a second light field, and phase modulators are arranged in one-to-one correspondence with the second light field; the light fields output by the phase shifting regions are marked as third light fields, and the phase difference between the third light fields is 0; the second coupling region comprises a beam combining structure, and the third optical field is completely coupled in to be combined into a terminal optical field. The coupling efficiency is high, the alignment tolerance is further improved, and a new degree of freedom is added for reducing the package insertion loss. The preparation method provided by the invention has corresponding advantages because the end face coupler can be prepared, has good compatibility with a CMOS (complementary metal oxide semiconductor) process, only needs one-time etching, and is beneficial to process optimization and production improvement.

Description

End face coupler and preparation method thereof

Technical Field

The invention belongs to the technical field of optical waveguide and integrated optics, and particularly relates to an end face coupler and a preparation method thereof.

Background

The coupling of the existing light sources such as laser or optical fiber and the like with the silicon optical chip mainly comprises two modes of grating coupling and end face coupling. The Grating coupling adopts the vertical coupling of the Grating coupler, which has the characteristic of mode field matching, has the advantages of larger alignment tolerance and realization of wafer level test, and also has the defects of polarization sensitivity, wavelength sensitivity, narrower bandwidth and the like, and the use of the Grating coupling scheme has certain limitation. The existing end face coupling scheme can realize polarization insensitivity and larger bandwidth, but the alignment tolerance is smaller, so that the wafer level packaging is not facilitated. Taking a DFB single-mode laser as an example, the size of a mode spot of an optical field output by the laser is about 2-3 μm, and the alignment tolerance of a corresponding 1dB end face coupler is below the micrometer size, so that the precision requirement on packaging equipment is high, but the precision of a current commercial flip-chip bonding machine is generally +/-1 μm, and the difficulty and the cost of packaging are greatly increased by adopting the existing scheme of end face coupling under the condition, and the yield of products is difficult to ensure. Alignment deviation generally refers to the offset of the corresponding coupling position when loss increases by 1dB, and even if an active packaging method is adopted, a large alignment deviation still occurs in the packaging curing process, so that the insertion loss of the device is increased. Silicon-based photonic devices, which have been widely focused in the industry in recent years, are increasingly applied due to their unique characteristics, such as low cost, ultra-small size, low power consumption, and compatibility with fine process characteristics, and particularly, are gradually paid attention to in the fields of laser radar and active laser detection.

Therefore, it is very necessary to research an end-face coupler and a corresponding manufacturing method, which are convenient for packaging, can increase the alignment tolerance between the light source and the silicon optical chip, do not increase the insertion loss of the device, and can ensure the yield level of the product. Thereby further promoting the deep development of the integrated optical technology and the wide application of the silicon-based photonic device.

Disclosure of Invention

The present invention is directed to solving all or some of the problems of the prior art described above and, in one aspect, to an end-face coupler. Another aspect of the present invention provides a method for manufacturing an end-face coupler, which can be used to manufacture the end-face coupler of the present invention.

The invention provides an end face coupler, which comprises a first coupling area, a phase shift area and a second coupling area, wherein the first coupling area, the phase shift area and the second coupling area are sequentially arranged along the direction of an output light field of a light source; the first coupling region comprises a beam splitting structure which splits an output light field of a light source into at least two first light fields and couples all of the first light fields into the phase shifting region; recording the light field in the phase shift region as a second light field, wherein phase modulators are arranged in the phase shift region in one-to-one correspondence with the second light field; the light field output by the phase shifting region is marked as a third light field; at least two third light fields are provided, and the phase difference between the third light fields is 0; the second coupling region comprises a beam combining structure, and the beam combining structure couples all the third optical fields into one terminal optical field. And coupling an external light source into the phase shift region through the first coupling region, if a phase difference exists between at least two second light fields due to alignment deviation, performing phase compensation through the phase shift region, so that no phase difference exists between the third light fields output from the phase shift region, combining the third light fields into a terminal light field through the beam combining structure, and outputting the terminal light field to a device, thereby improving the alignment tolerance of the light source and the silicon optical chip, and simultaneously improving the final coupling efficiency. After the conventional end-face coupler is packaged with the optical fiber or the laser, the coupling loss value is determined, but in the packaging process, no matter active packaging or passive packaging is adopted, the optical fiber or the laser and the silicon optical chip have some inevitable deviation. The end face coupler provided with the phase modulator can reduce the coupling loss caused by the deviation by controlling the phase modulator to perform phase modulation after the laser or the optical fiber and PIC are packaged, thereby achieving the purpose of further reducing the coupling loss and increasing a new degree of freedom for reducing the package insertion loss.

In a general case, the first coupling region, the phase-shifting region and the second coupling region are arranged on a silicon substrate layer. The end face coupler is directly generated on the silicon substrate layer of the silicon optical chip, and the end face coupler has good compatibility with a CMOS (complementary metal oxide semiconductor) process and is easy to prepare.

The phase modulator is a thermo-optic phase shifter, an electro-optic phase shifter or a PN junction type optical phase shifter. The phase modulators are at least two, and can select one of a thermo-optic phase shifter, an electro-optic phase shifter or a PN junction type optical phase shifter of the same type, or select several phase shifters of different types. And selecting according to practical application.

The phase modulator is a thermo-optic phase shifter; the thermo-optic phase shifter comprises a single-mode waveguide with a preset length, a heating unit arranged at a first interval with the single-mode waveguide, and an exposed electrode electrically connected with the heating unit; the minimum distance between the thermo-optic phase shifters is a second pitch; the value of the first distance is determined by the heating unit not influencing the transmission loss of the single-mode waveguide; the second pitch is selected to minimize thermal crosstalk generated between the thermo-optic phase shifters. The exposed electrode is used for electrifying the heating unit, heating and modulating the phase of the second optical field in the single-mode waveguide, and the phase is changed by adjusting electric power through the exposed electrode so as to control the coupling light intensity. The phase modulators are all thermo-optic phase shifters, and the thermo-optic phase shifters are simple in structure and convenient to manufacture, and are beneficial to simplifying the process and saving the cost.

Preferably, the value range of the first distance is 0.5-2 μm.

The second pitch is greater than 40 μm. The preset length range is 50-500 mu m.

The beam splitting structure comprises at least two first waveguide structure units; the center distance between the first waveguide structure units is a first preset distance; the first waveguide structure unit comprises a plurality of first waveguides, and at least one part of each first waveguide gradually becomes narrow and wide along the direction of an output optical field of the light source; the input end of the first waveguide is provided with a first tapered sub-wavelength grating. The first preset distance determines the coupling loss and the alignment tolerance of the end face coupler and the light source, the larger the first preset distance is, the larger the alignment tolerance is, the coupling loss under the condition of no offset is correspondingly increased, and in practical application, the first preset distance can be set according to the specific use condition of the end face coupler, and meanwhile, the coupling loss and the alignment tolerance are considered, so that the specific requirements in production are met.

Preferably, the first waveguide structure unit further includes sub-wavelength grating waveguides disposed at two sides of the first waveguide, and the input end of the sub-wavelength grating waveguides is disposed with a second tapered sub-wavelength grating; the first waveguide and the sub-wavelength grating waveguides on two sides of the first waveguide form a trident structure; the first waveguide and the sub-wavelength grating waveguide are Silicon-on-insulator (SOI) waveguides. The use of the trident structure composed of SOI waveguides is beneficial to further reducing the coupling loss, and on the other hand, the structure is compatible with the CMOS process and easy to prepare the waveguide layer structure.

Specifically, the first waveguide is a single-mode waveguide; the first waveguides are arranged parallel to each other.

The plurality of first waveguides are two independent single-mode waveguides which are arranged in parallel, and the first preset distance is the center distance between the two single-mode waveguides.

The beam combining structure comprises two second waveguide structure units arranged at intervals of a second preset distance and a third waveguide arranged between the second waveguide structure units; the second waveguide structure unit comprises a plurality of second waveguides; the third optical field is coupled into the third waveguide by evanescent waves to be the terminal optical field. The beam combining structure realizes beam combining of the third optical field in the third waveguide by two second waveguide structure units in an evanescent wave coupling mode, and is favorable for realizing lower insertion loss and larger bandwidth of the device. The second preset distance influences the coupling length of the second coupling region, the coupling length of the second coupling region can be adjusted by setting the second preset distance in cooperation with the specific design of a device in practical application, and specific requirements in the overall structure design of the device are met.

The second waveguide is a separate single mode waveguide; the second waveguides are arranged parallel to each other. At least one portion of the second waveguide is gradually narrowed from wide in a direction away from the phase shifting region; at least a portion of the third waveguide is tapered from narrow to wide.

The second waveguide and the third waveguide are SOI (Silicon-on-insulator) waveguides.

Another aspect of the present invention provides a method for manufacturing an end-face coupler, including: and forming a waveguide layer structure of the first coupling region, the phase shift region and the second coupling region by one-time etching.

The phase shifting device is characterized by further comprising a plurality of heating units which are correspondingly arranged on the plurality of waveguides of the waveguide layer structure of the phase shifting region at intervals of preset first intervals, and exposed electrodes are arranged on the heating units.

Compared with the prior art, the invention has the main beneficial effects that:

1. the end face coupler is simple in structure, and can enable the alignment tolerance of a light source and a silicon optical chip in the horizontal direction to be remarkably increased by coupling an external light source into the phase shift region through the first coupling region; no matter which side of the light source in the horizontal direction of the end face coupler deviates, the phase difference between the second light fields caused by the alignment deviation can be compensated through the phase shifting region, and finally the coupling efficiency is higher; the phase modulator can be arranged after the laser or the optical fiber and the PIC are packaged, so that the coupling loss caused by the deviation can be reduced, the aim of further reducing the coupling loss is fulfilled, and a new degree of freedom is added for reducing the package insertion loss. The beam combining structure performs beam in optical field in evanescent wave coupling mode, and the device has larger bandwidth and lower insertion loss

2. The preparation method of the end face coupler can be used for preparing the end face coupler, has simple steps, only needs one-step etching, has good compatibility with a CMOS (complementary metal oxide semiconductor) process, does not increase an additional production process, saves the cost, and is easy for enterprises to prepare the end face coupler on the basis of the existing process.

Drawings

Fig. 1 is a schematic view of an application scenario of an end-face coupler according to a first embodiment of the present invention.

Fig. 2 is a schematic top view of an end-face coupler according to a first embodiment of the invention.

Fig. 3 is a schematic cross-sectional view of a thermo-optic phase shifter according to a first embodiment of the invention.

Fig. 4(a) and 4(b) are schematic diagrams illustrating the operation principle of the end-face coupler structure according to the first embodiment of the present invention.

Fig. 5 is a schematic diagram illustrating a simulation of mode field distribution of the end-face coupler without offset according to the first embodiment of the present invention.

Fig. 6 is a simulation diagram of the relationship between the heating power and the alignment offset according to the first embodiment of the invention.

Fig. 7 is a simulation diagram of the horizontal alignment deviation between the end-face coupler according to the first embodiment of the present invention and the conventional coupling structure.

Fig. 8 is a schematic top view of an end-face coupler according to a second embodiment of the present invention.

Fig. 9 is a schematic diagram of a method for manufacturing an end-face coupler according to a second embodiment of the present invention.

Detailed Description

The technical solutions in the specific embodiments of the present invention will be clearly and completely described below, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings. In the figures, parts of the same structure or function are denoted by the same reference numerals, and not all parts shown are denoted by the associated reference numerals in all figures for reasons of clarity of presentation.

The operations of the embodiments are depicted in the following embodiments in a particular order, which is provided for better understanding of the details of the embodiments and to provide a thorough understanding of the present invention, but the order is not necessarily one-to-one correspondence with the methods of the present invention, and is not intended to limit the scope of the present invention.

It is to be noted that the flow charts and block diagrams in the figures illustrate the operational procedures which may be implemented by the methods according to the embodiments of the present invention. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the alternative, depending upon the functionality involved. It is also noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and manual acts.

Example one

In the first embodiment of the present invention, as shown in fig. 1 and fig. 2, the end-face coupler C includes an output light field L along the light Source₀The first coupling area I, the phase shift area X and the second coupling area II are sequentially arranged in the direction; the phase shift section X includes phase modulators, a first phase modulator T1 and a second phase modulator T2, respectively, symmetrically disposed on both sides of the central axis N of the end-face coupler C; the first coupling region I comprises a beam splitting structure P for splitting an output light field L of a light Source₀Divided into at least two first light fields L₁And applying the first light field L₁All coupled into phase shift region X; the light field within the phase shift region X is denoted as a second light field L₂In this embodiment, the second light field L₂Two, the first phase modulator T1 and the second phase modulator T2 are provided in one-to-one correspondence therewith. The light field output from the phase shifting region, denoted as the third light field L₃In this embodiment, the third light field L₃With two, third light fields L₃The phase difference therebetween is 0; the second coupling region II comprises a beam combining structure Q and a second light field L₂All the light beams are coupled into a beam combining structure Q and combined into a terminal light field L_fin. In this exampleThe first coupling area I, the phase shift area X and the second coupling area II are all arranged on the silicon substrate layer. The end face coupler C is directly generated on the silicon substrate layer of the silicon optical chip, and the end face coupler C is easy to prepare and compatible with a CMOS (complementary metal oxide semiconductor) process. In the description of the embodiments for facilitating understanding of the present invention, the exemplary case where the alignment offset is 0 refers to the case where the output light field of the light Source is incident along the central axis N of the end-face coupler C, but the specific case of the present invention is not limited thereto.

The first phase modulator T1 and the second phase modulator T2 may be selected from a thermo-optical phase shifter, an electro-optical phase shifter, a PN junction optical phase shifter, and the like, or different specific phase modulators may be used for the first phase modulator T1 and the second phase modulator T2 according to practical applications, and are not limited. In this embodiment, the first phase modulator T1 and the second phase modulator T2 are both a thermo-optic phase shifter; as shown in FIG. 1, the output light field L in this embodiment₀Is divided into two first light fields L₁All coupled-in phase shifting regions X correspond to two second light fields L₂. One first phase modulator T1 and one second phase modulator T2 are provided for modulating a second light field L₂. I.e. the number of thermo-optical phase shifters is 2. The total number of first phase modulators T1, second phase modulators T2, i.e. the number of said phase modulators is equal to the second light field L₂The number of the cells. The thermo-optic phase shifter in this embodiment specifically includes a single-mode waveguide of a predetermined length, a heating unit Heater disposed above the single-mode waveguide at a first distance D1, and an exposed electrode (not shown) electrically connected to the heating unit Heater. As shown in fig. 3, the single-mode waveguide in this embodiment is an SOI waveguide, and the preset length range thereof is 50 μm to 500 μm, and specifically, the preset lengths of the single-mode waveguides of the thermo-optic phase shifter in this embodiment are all equal and are 100 μm. The value of the first distance D1 is based on the fact that the heating element Heater does not affect the transmission loss of the single-mode waveguide. In this embodiment, the Heater unit Heater is specifically a metal wire, and has a certain distance from the SOI waveguide below, that is, the first distance D1, and under the condition that the waveguide loss is not affected as much as possible, the smaller the first distance is, the better the first distance is, and the value selected by the first distance D1 in this embodiment is 1 μm. First distance D in practical applicationA preferable value range of 1 can be 0.5-2 μm to ensure that the transmission loss of the waveguide is not affected. The present embodiment takes the structure of the thermo-optic phase shifter as an example, but is not limited to this structure. The thermo-optic phase shifter of the present embodiment is designed because the structure is simple and can meet the application requirements. The thermo-optic phase shifter based on other principles and having different specific structures can also meet specific requirements according to practical application conditions, and is not limited. As shown in fig. 2, the first phase modulator T1 and the second phase modulator T2 are separated by a second distance D2, which is the minimum distance between the two thermo-optic phase shifters, and in order to ensure that the thermal crosstalk generated between the thermo-optic phase shifters is as small as possible, the second distance D2 is generally larger than 40 μm, which is a specific practice of this embodiment, the minimum distance between the two thermo-optic phase shifters is 50 μm. The thermo-optic phase shifters in this embodiment have their single mode waveguides parallel to each other and the heating elements Heater are correspondingly parallel to each other, with the two thermo-optic phase shifters being spaced apart by a minimum distance, i.e. the perpendicular distance between the opposite edges of the two heating elements Heater. In some embodiments, the thermo-optic phase shifters are not necessarily arranged in parallel in the same plane, and the minimum distance between the thermo-optic phase shifters should satisfy the preset second spacing D2 to avoid thermal crosstalk. The exposed electrode is used for electrifying the heating unit Heater to heat and modulate a second optical field L in the single-mode waveguide₂The phase of the optical field in the two single-mode waveguides is specifically changed by adjusting the temperature of Heater metal wires of the heating unit through the exposed electrodes so as to control the coupling light intensity.

In this embodiment, the beam splitting structure P includes two first waveguide structure units S1 symmetrically disposed on both sides of the central axis N; the center distance between the first waveguide structure units S1 is a first preset distance W1; the first waveguide structural unit S1 specifically includes a first waveguide 1, and the first waveguide 1 is along the output light field L of the light Source₀At least one part of the direction of the first and second guide rails is gradually narrowed and widened; the input end of the first waveguide 1 is provided with a first tapered sub-wavelength grating 11. In this embodiment, two first waveguides 1 are provided in parallel with each other. The straight waveguide part of the first waveguide 1 continues into the phase shift region X corresponding to the thermo-optic phase shiftThe single-mode waveguide of the waveguide is continuous and integrated into a structure. The first waveguide 1 in this embodiment is a single mode waveguide; the first predetermined distance W1 is the center-to-center distance between the straight waveguides of the two first waveguides 1 in the first coupling region i, and the first predetermined distance W1 is 2.2 μm in this embodiment. The first waveguide structural unit S1 in this embodiment further includes sub-wavelength grating waveguides disposed on two sides of each first waveguide 1, and the input end of each sub-wavelength grating waveguide is provided with a second tapered sub-wavelength grating 12; the first waveguide 1 and the sub-wavelength grating waveguides on both sides thereof form a trident structure. In this embodiment, each of the first waveguide structure units adopts a set of trident structures, which is beneficial to further reduce the coupling loss. In this embodiment, the waveguides of the first waveguide structural unit S1 are all SOI waveguides, that is, the first waveguide 1 and the sub-wavelength grating waveguides arranged on both sides thereof, and the first tapered sub-wavelength grating 11 and the second tapered sub-wavelength grating 12 are all silicon (Si) on insulator waveguides.

In this embodiment, the beam combining structure Q includes two second waveguide structural units S2 symmetrically disposed on both sides of the central axis N, and a third waveguide 3 having a length direction along the central axis of the coupler; the center-to-center distance between the second waveguide structure units S2 is a second predetermined distance (not shown). The second waveguide structural unit S2 includes a second waveguide 2; the third light field L₃Respectively coupled into a third waveguide 3 from the second waveguide 2 through evanescent waves to form a terminal optical field L_fin. The beam combination structure Q realizes beam combination in the third waveguide 3 by two second waveguide structure units S2 in an evanescent coupling manner, which is beneficial to realizing lower insertion loss and larger bandwidth of the device. The second preset distance can influence the coupling length of the second coupling area II, the coupling length of the second coupling area II can be adjusted by setting the second preset distance in cooperation with the specific design of a device in practical application, and the specific requirements in the structural design of the device are met. The second waveguide 2 is two independent single-mode waveguides symmetrically arranged in parallel with the center distance of the two sides of the central axis N being the second preset distance. In this embodiment, the portion of the single-mode waveguide of the thermo-optic phase shifter in the phase shift region X that continues into the beam combining structure Q constitutes the second waveguide 2. At least one part of the second waveguide 2 is gradually formed byThe width is narrowed; the third waveguide 3 is gradually narrowed and widened at least in a corresponding portion. The second waveguide 2 and the third waveguide 3 are SOI (Silicon-on-insulator) waveguides. In the present embodiment, the first waveguide 1, the second waveguide 2, and the third waveguide 3 are single-mode waveguides that are continuously integrated in a waveguide layer structure, which is an example for facilitating intuitive understanding of the present invention, and other curved forms are possible as long as the second distance D2 can meet the design requirement, which is not limited. In other embodiments, the beam splitting structure P and the beam combining structure Q may also be implemented by, but not limited to, Y beam splitter (or combiner), 1 × 2MMI structure, and the like.

As shown in fig. 4(a) and 4(b), the first predetermined distance W1 determines the coupling loss and the alignment tolerance of the end-face coupler C and the light Source, and the larger the first predetermined distance W1, the larger the alignment tolerance, the coupling loss in the case of no offset will be increased accordingly. The specific working principle of this embodiment is that when the light Source and the end-face coupler C have alignment deviation, the first light fields L of the first waveguide structural units S1 respectively coupled into the two sides of the central axis N₁There are differences in intensity and phase, two first light fields L on both sides of the central axis N_１Complex amplitude of

Are expressed by the following two formulas respectively:

the second light field L, which is not phase modulated by the first phase modulator T1 or the second phase modulator T2 in this embodiment₂I.e. the first light field L₁. When the alignment deviation Δ x is shown in FIG. 4(a)>When 0 (i.e., when the center axis is deviated to the lower side of N), phi₁>φ₂The second light field L below the central axis N may now be increased by heating the wire of the second phase modulator T2₂So that a phase ofOutputting a third light field L of the phase shift region X through the single-mode waveguide on both sides of the central axis N₃The phase difference therebetween is 0. When the alignment deviation Deltax is shown in FIG. 4(b)<When 0 (i.e., when it is deviated to the upper side of the central axis N), phi₁<φ₂At this time, the second light field L on the lower side of the central axis N can be increased by heating the metal wire of the first phase modulator T1₂So that the third optical field L of the phase shift region X is output through the single-mode waveguide on both sides of the central axis N₃The phase difference therebetween is 0. When the alignment deviation Δ x =0 (i.e., when the central axis N is aligned), Φ₁=φ₂At this time, no phase adjustment is required, the first phase modulator T1 and the second phase modulator T2 are not operated, and the first light field L is adjusted₁A second light field L₂And a third light field L₃Are the same light field. The simulation diagram of the mode field distribution without offset is shown in fig. 5. A simulation of heating power versus alignment shift is shown in fig. 6. The simulation results of the alignment deviation of the end-face coupler C and the two coupling structures (single trident structure; double trident structure) in the horizontal direction are shown in fig. 7. The misalignment generally refers to the amount of coupling position shift corresponding to 1dB loss increase, as shown in FIG. 7, the 1dB misalignment of the end-face coupler C of this embodiment is + -1.7 μm, while the 1dB misalignment of the two existing sub-wavelength trident structures is + -0.65 μm and + -0.77 μm, respectively. It follows that the end-face coupler C of the present embodiment has a greater range of alignment tolerances.

Example two

As shown in fig. 8, the second embodiment differs from the first embodiment mainly in that the beam splitting structure P includes 4 independent single-mode waveguides on both sides of the central axis N. Each second waveguide structure unit S2 includes two second waveguides 2, which are also independent single-mode waveguides. The second light field L₂There are 4, and thus there are 2 first phase modulators T1 and 2 second phase modulators T2.

The method for manufacturing the end-face coupler in this embodiment, as shown in fig. 9, includes: forming a waveguide layer structure of the first coupling area, the phase shift area and the second coupling area by one-time etching; and correspondingly arranging a plurality of heating units on a plurality of waveguides of the waveguide layer structure of the phase shift region at preset first intervals, and arranging exposed electrodes on the heating units. The specific size and specific structure of the end-face coupler can be designed according to the wavelength and the spot size of the light source in practical application, and the end-face coupler can be applied to the coupling application of various light sources without limitation.

For clarity of description, the use of certain conventional and specific terms and phrases is intended to be illustrative and not restrictive, but rather to limit the scope of the invention to the particular letter and translation thereof. It is further noted that, herein, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. The structure and operation of the present invention are explained by applying specific examples, and the above description of the embodiments is only used to help understanding the method and core idea of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the principles of the invention, and it is intended that such changes and modifications also fall within the scope of the appended claims.

Claims

1. An end-face coupler, characterized by: the phase-shifting grating comprises a first coupling region, a phase-shifting region and a second coupling region which are sequentially arranged along the direction of an output light field of a light source;

the first coupling region comprises a beam splitting structure which splits an output light field of a light source into at least two first light fields and couples all of the first light fields into the phase shifting region;

recording the light field in the phase shift region as a second light field, wherein phase modulators are arranged in the phase shift region in one-to-one correspondence with the second light field; the light field output by the phase shifting region is marked as a third light field; at least two third light fields are provided, and the phase difference between the third light fields is 0;

the second coupling region comprises a beam combining structure, and the beam combining structure couples all the third optical fields into one terminal optical field.

2. The end-face coupler of claim 1, wherein: the first coupling region, the phase-shifting region, and the second coupling region are disposed on a silicon substrate layer.

3. The end-face coupler of claim 1, wherein: the phase modulator adopts one or more of a thermo-optic phase shifter, an electro-optic phase shifter or a PN junction type optical phase shifter.

4. The end-face coupler of claim 1, wherein: the phase modulator is a thermo-optic phase shifter;

the thermo-optic phase shifter comprises a single-mode waveguide with a preset length, a heating unit arranged at a first interval with the single-mode waveguide, and an exposed electrode electrically connected with the heating unit;

the minimum distance between the thermo-optic phase shifters is a second pitch;

the value of the first distance is determined by the heating unit not influencing the transmission loss of the single-mode waveguide; the second pitch is selected to minimize thermal crosstalk generated between the thermo-optic phase shifters.

5. The end-face coupler of claim 4, wherein: the value range of the first distance is 0.5-2 mu m.

6. The end-face coupler of claim 4, wherein: the second pitch is greater than 40 μm; the preset length range is 50-500 mu m.

7. The end-face coupler of claim 1, wherein: the beam splitting structure comprises at least two first waveguide structure units; the center distance between the first waveguide structure units is a first preset distance;

the first waveguide structure unit comprises a plurality of first waveguides, and at least one part of each first waveguide gradually becomes narrow and wide along the direction of an output optical field of the light source; the input end of the first waveguide is provided with a first tapered sub-wavelength grating.

8. The end-face coupler of claim 7, wherein: the first waveguide structure unit further comprises sub-wavelength grating waveguides arranged on two sides of the first waveguide, and the input end of each sub-wavelength grating waveguide is provided with a second tapered sub-wavelength grating; the first waveguide and the sub-wavelength grating waveguides on two sides of the first waveguide form a trident structure; the first waveguide and the sub-wavelength grating waveguide are SOI waveguides.

9. The end-face coupler of claim 7, wherein: the first waveguide is a single mode waveguide; the first waveguides are arranged parallel to each other.

10. The end-face coupler according to any of claims 1-9, wherein: the beam combining structure comprises two second waveguide structure units arranged at intervals of a second preset distance and a third waveguide arranged between the second waveguide structure units;

the second waveguide structure unit comprises a plurality of second waveguides; the third optical field is coupled into the third waveguide by evanescent waves to be the terminal optical field.

11. The end-face coupler of claim 10, wherein: the second waveguide is a separate single mode waveguide; the second waveguides are arranged in parallel;

at least one portion of the second waveguide is gradually narrowed from wide in a direction away from the phase shifting region; at least a portion of the third waveguide is tapered from narrow to wide.

12. The end-face coupler of claim 10, wherein: the second waveguide and the third waveguide are SOI waveguides.

13. A method of making an end-face coupler according to any of claims 1 to 12, wherein: the method comprises the following steps: and forming a waveguide layer structure of the first coupling region, the phase shift region and the second coupling region by one-time etching.

14. The method of claim 13, wherein: the phase shifting device is characterized by further comprising a plurality of heating units which are correspondingly arranged on the plurality of waveguides of the waveguide layer structure of the phase shifting region at intervals of preset first intervals, and exposed electrodes are arranged on the heating units.