CN116577873A - Dynamic polarization controller based on silicon-based photoelectron chip - Google Patents

Abstract

The invention discloses a dynamic polarization controller based on a silicon-based optoelectronic chip, which can lock any polarization state light field to any desired polarization state light field. The controller couples the light of any polarization state light field from the single-mode fiber into the chip through the first high numerical aperture fiber through the first end face coupling structure; after passing through the first polarization rotating beam splitter (PRS), it enters the chip Both TE0 mode and TM0 mode light fields are converted into TE0 mode light fields; after the polarization is locked by the waveguide 0°/45°/0° structure, the two TE0 mode light fields are combined into one through the second polarization rotating beam splitter After the beam is converted into TE0 mode and TM0 mode light field, it is output to the second high numerical aperture optical fiber relay through the second end face coupling structure and then enters the single-mode optical fiber. The waveguide 0°/45°/0° structure adopts an electronically controlled phase shifter, combined with simulated annealing algorithm, gradient algorithm and other algorithms to automatically lock the polarization state of light.

Description

A Dynamic Polarization Controller Based on Silicon-Based Optoelectronic Chip

technical field

The invention relates to the field of quantum secure communication, in particular to a dynamic polarization controller based on a silicon-based optoelectronic chip.

Background technique

The continuous variable quantum security communication system adopts time division multiplexing and polarization multiplexing technology to transmit the signal light field and the local oscillator light field in the same long-distance single-mode fiber. Due to external factors, temperature, humidity, etc. during transmission, the single-mode fiber will produce a birefringence effect, resulting in a change in the polarization state in the single-mode fiber. Bob at the receiving end needs to use a dynamic polarization controller to recover and lock the polarizations of the two light fields to the linear polarization state. The locked two light fields are re-divided into the signal light field light path and the local oscillator light path through the polarization beam splitter. Traditional polarization controllers include three-ring polarization controllers, electronically controlled polarization controllers, etc. These polarization controllers are usually bulky, have slow response rates, and consume high power.

Silicon-based optoelectronics emerged in the 1980s. By using the technology on silicon-based integrated circuits to design, manufacture, and package optical devices and optoelectronic integrated circuits, it has reached the level of integrated circuits in terms of integration, manufacturability and expansion. So as to achieve breakthroughs in cost, power consumption, and size. A research group has developed a dynamic polarization controller based on a silicon-based chip. The document "Siliconphotonics integrated dynamic polarization controller. Chin. Opt. Lett., 041301, 2022." uses a waveguide 0°/45°/0° /45° four locking structures, this document uses a two-dimensional grating to couple the light field between the single-mode fiber and the silicon-based optoelectronic chip. The thermal phase shifter on the base optoelectronic chip can determine the characteristics of the phase, and the method of dual phase simultaneous control under a single 0° or 45° structure is not adopted.

Contents of the invention

Aiming at the problems existing in the existing dynamic polarization controller, the present invention designs a dynamic polarization controller based on a silicon-based optoelectronic chip, which can lock any polarization state light field to any polarization state light field. The device adopts end-face coupling technology and polarization rotation beam splitting technology, which can effectively reduce the coupling loss and realize low-loss beam splitting and beam combining in the polarized light field; the array fiber coupling interface FA is used to realize the same-side end-face coupling input port and output port, which is easy to couple And packaging; based on the equivalent waveguide 0°/45°/0° structure of the electronically controlled phase shifter on the silicon-based optoelectronic chip to achieve endless polarization control; it has the characteristics of low cost, low power consumption, and small size. To this end, the invention provides a dynamic polarization controller based on a silicon-based optoelectronic chip.

In order to achieve the expected effect of theoretical analysis and experimental verification of the above-mentioned technical solutions, the present invention adopts the following technical solutions:

A dynamic polarization controller based on a silicon-based optoelectronic chip, including a silicon-based optoelectronic chip, the side of the silicon-based optoelectronic chip is connected with an input and output structure, and the silicon-based optoelectronic chip is respectively provided with input and output structures. A first end-face coupling structure connected to the ends and a second end-face coupling structure connected to the output end of the input-output structure, the first end-face coupling structure and the second end-face coupling structure are sequentially connected with a first polarization rotating beam splitter, A first polarization control structure, a second polarization control structure, a third polarization control structure, and a second polarization rotating beam splitter.

As a further improvement of the above solution, the input and output structure includes an array fiber FA port, a first fiber connector and a second fiber connector, and the array fiber FA port includes a first high numerical aperture fiber as an input port and a first high numerical aperture fiber as an output port. The second high numerical aperture optical fiber at the end, one end of the first high numerical aperture optical fiber is connected to the first end-face coupling structure, and the other end is connected to the first optical fiber connector through a single-mode optical fiber, and one end of the second high numerical aperture optical fiber is connected to the first end surface coupling structure. The two ends are connected by a coupling structure, and the other end is connected with a second optical fiber connector through a single-mode optical fiber.

As a further improvement of the above solution, both the first end face coupling structure and the second end face coupling structure are configured as trapezoidal end face coupling structures.

As a further improvement of the above scheme, the first polarization control structure includes a first electronically controlled phase shifter and a second electrically controlled phase shifter, and the first electrically controlled phase shifter and the second electrically controlled phase shifter realize 0° polarization control function; the second polarization control structure includes a first 50/50 coupler, a third electrically controlled phase shifter, a fourth electrically controlled phase shifter and a second 50/50 coupler, the first An electronically controlled phase shifter, the first 50/50 coupler, the third electrically controlled phase shifter, the fourth electrically controlled phase shifter, the second 50/50 coupler and the sixth electrically controlled phase shifter realize 45° polarization Control function; the third polarization control structure includes a fifth electrically controlled phase shifter and a sixth electrically controlled phase shifter, and the fifth electrically controlled phase shifter and the sixth electrically controlled phase shifter realize the 0° polarization control function.

As a further improvement of the above scheme, the first electronically controlled phase shifter is powered by the first pad and the second pad; the second electronically controlled phase shifter is powered by the third pad and the second pad, and the second pad is a common terminal; the third electrically controlled phase shifter is powered by the fourth pad and the fifth pad; the fourth electrically controlled phase shifter is powered by the sixth pad and the fifth pad, and the fifth pad is the public The fifth electrically controlled phase shifter is powered by the seventh pad and the eighth pad; the sixth electrically controlled phase shifter is powered by the ninth pad and the eighth pad, and the eighth pad is a common terminal.

As a further improvement of the above solution, the first polarization rotating beam splitter is composed of a first polarization rotating part and a first polarization splitting part; the first polarization rotating part is composed of a first partially etched waveguide and the first half of the first transitional waveguide ; The first polarization splitting part is composed of the second half of the first transitional waveguide and the first adiabatic waveguide; the second polarization rotation beam splitter is composed of the second polarization splitting part and the second polarization rotation part; the second polarization splitting part It is composed of the second half of the second transition waveguide and the second adiabatic waveguide; the second polarization rotation part is composed of the second partially etched waveguide and the first half of the second transition waveguide.

As a further improvement of the above solution, a first compensation waveguide is connected between the first polarization control structure and the second polarization control structure to ensure that the waveguide from the first polarization beam splitter to the first 50/50 coupler The lengths are equal; the second compensation waveguide is connected between the second polarization control structure and the second polarization rotating beam splitter, so as to ensure that the lengths of the waveguides from the second 50/50 coupler to the second polarization beam splitter are equal.

A control method using a dynamic polarization controller based on a silicon-based optoelectronic chip, comprising the following steps:

Step 1: The light field of any polarization state in the external single-mode fiber is input to the first high numerical aperture fiber through the first fiber connector in the input-output structure for mode spot conversion, and then transmitted to the first end-face coupling structure after mode spot matching Finally, the mode spot is further converted and transmitted to the first polarization rotating beam splitter, and the arbitrary polarization state light field entering the first polarization rotating beam splitter is divided into the fundamental mode light field T0 mode of the TM mode and the fundamental mode of the TE mode The TE0 mode of the light field, wherein the TM0 mode light field is transformed into the TE mode high-order mode light field TE1 mode through the first polarization rotation, and the TE0 mode light field does not convert; then the TE1 mode light field and the TE0 mode light field enter into the first polarization In the beam splitting part, the TE0 mode light field is output along the first transition waveguide without mode conversion, and is output from the first transition waveguide port of the first polarization rotating beam splitter, and the TE1 mode light field is coupled from the first transition waveguide to the first transition waveguide In the adiabatic waveguide, it is output from the first adiabatic waveguide port of the first polarization rotating beam splitter, and the mode is converted to TE0, and two beams of light whose polarization is both TE0 mode are output from the first polarization rotating beam splitter;

Step 2: The light fields of the two beams of TE0 mode output from the first polarization rotating beam splitter enter the first polarization control structure, the second polarization control structure and the third polarization control structure in sequence; the first polarization control structure, the second polarization control structure Both the second polarization control structure and the third polarization control structure use electronically controlled phase shifters to generate phase delays;

Step 3: After passing through the three polarization locking structures, the light field of the two beams of TE0 mode output from the third polarization control structure enters the second polarization rotating beam splitter, and the light coming out of the sixth electronically controlled phase shifter Entering the second transition waveguide, the light coming out of the fifth electronically controlled phase shifter enters the second adiabatic waveguide, the light in the TE0 mode in the second transition waveguide is still transmitted along the second transition waveguide in the TE0 mode and the mode No change occurs, the light of the TE0 mode in the second adiabatic waveguide is coupled from the second adiabatic waveguide to the second transitional waveguide in the second polarization beam splitting part and the mode is converted into a TE1 mode, and the two beams are combined into one beam, and then enter the The second polarization rotation part, the second polarization rotation part converts the TE1 mode into the TM0 mode, and the TE0 mode does not convert, and then the light of the two modes of TM0 and TE0 is input into the second end-face coupling structure, after the mode spot conversion and matching Then output to the second high numerical aperture optical fiber in the input-output structure, the mode spot is converted again and then output through the second optical fiber joint.

Compared with the prior art, the present invention has the following advantages:

1. The present invention adopts the array end face coupling structure to perform mode spot matching and coupling packaging with the array high numerical aperture optical fiber. The end-face coupling structure can match the mode spot radius of the waveguide in the chip with the mode spot radius of the high numerical aperture fiber in order to reduce the loss caused by the difference between the two mode spot radii and achieve a lower coupling loss of about 2dB . In the 1550nm band, the mode spot size of the single-mode waveguide is about 0.4 μm, and the mode spot radius is expanded to 3.5 μm after the end-face coupling structure. This size matches the 3.5µm mode spot size of high numerical aperture fibers.

2. The present invention uses a waveguide 0°/45°/0° structure to lock the polarization state of the light field. Through three polarization locking structures, the endless control of the polarization state can be realized, and any input polarization state can be locked to any required output. Polarization state, and can achieve a dynamic extinction ratio greater than 25dB. The dynamic polarization controller makes full use of the characteristics of precise phase control of the electronically controlled phase shifter and the dual-voltage control characteristics of the same polarization control structure, without the need for a 0°/45°/0°/45° structure.

3. The dynamic polarization controller designed in the present invention adopts silicon-based optoelectronic integration technology. Compared with the traditional dynamic polarization controller, it has the advantages of small size, low power consumption, and low cost, and is convenient for use in the field of quantum information technology such as quantum communication. Large-scale production and application.

Description of drawings

Fig. 1 is a structural representation of a dynamic polarization controller based on a silicon-based optoelectronic chip in the present invention;

Fig. 2 is a structural schematic diagram of an end face coupling structure in the present invention;

FIG. 3 is a schematic structural view of the first polarization rotating beam splitter in the present invention;

FIG. 4 is a schematic structural view of a second polarization rotating beam splitter in the present invention;

Fig. 5 is the experimental apparatus figure in the embodiment of the present invention;

Fig. 6: is the diagram of the relationship between power consumption and phase shift of the electronically controlled phase shifter in the embodiment of the present invention;

Fig. 7: It is the result diagram of the polarization locking obtained after applying the specific embodiment of the present invention to carry out the experiment;

In the figure: a silicon-based optoelectronic chip 1, an input-output structure 2, a first end-face coupling structure 3, a first polarization rotating beam splitter 4, a first polarization control structure 5, a second polarization control structure 6, and a third polarization control structure 7 , the second polarization rotating beam splitter 8, the second end face coupling structure 9, the array fiber FA port 10, the first high numerical aperture optical fiber 11, the second high numerical aperture optical fiber 12, the first optical fiber connector 13, the second optical fiber connection Head 14, first electronically controlled phase shifter 15, second electronically controlled phase shifter 16, first 50/50 coupler 17, third electronically controlled phase shifter 18, fourth electronically controlled phase shifter 19, second 50/50 coupler 20, the fifth electrically controlled phase shifter 21, the sixth electrically controlled phase shifter 22, the third pad 23, the first pad 24, the second pad 25, the sixth pad 26, the Four bonding pads 27, fifth bonding pads 28, ninth bonding pads 29, seventh bonding pads 30, eighth bonding pads 31, first compensation waveguide 32, second compensation waveguide 33, first polarization rotation part 34, first Polarization beam splitting part 35, second polarization beam splitting part 36, second polarization rotation part 37, 1550nm fiber pigtail DFB laser 38, adjustable optical attenuator 39, 50/50 beam splitter 40, first power meter 41, Manual polarization controller 42, polarization beam splitter 43, second power meter 44, photodetector 45, USB6259 acquisition card acquisition end 46, computer control end 47, USB6259 acquisition card output end 48, first part etched waveguide 49, second A transitional waveguide 50 , a first adiabatic waveguide 51 , a second partially etched waveguide 52 , a second transitional waveguide 53 , and a second adiabatic waveguide 54 .

Detailed ways

In order to further illustrate the technical solution of the present invention, within the scope of protection described in the content of the invention above, we will further illustrate the specific implementation of the present invention by selecting the best examples below.

A dynamic polarization controller based on a silicon-based optoelectronic chip provided by the present invention includes a silicon-based optoelectronic chip 1, the side of the silicon-based optoelectronic chip 1 is connected to an input-output structure 2, and the input-output structure 2 includes an array fiber FA port 10, The first optical fiber connector 13 and the second optical fiber connector 14, the array fiber FA port 10 includes the first high numerical aperture optical fiber 11 as the input end and the second high numerical aperture optical fiber 12 as the output end, the first high numerical aperture optical fiber 11 One end is connected to the first end-face coupling structure 3, and the other end is connected to the first optical fiber connector 13 through a single-mode optical fiber, and the first high numerical aperture optical fiber 11 is used as an input fiber to perform optical coupling with the first end-face coupling structure 3 to realize the mode spot Matching, inputting any polarization state light field light into the first end-face coupling structure 3; one end of the second high numerical aperture optical fiber 12 is connected to the second end-face coupling structure 9, and the other end is connected to the second optical fiber connector 14 through a single-mode fiber ; The second high numerical aperture optical fiber 12 is used as the output fiber and the second end face coupling structure 9 for optical coupling to realize mode spot matching, and the locked arbitrary polarization state light field is output from the second end face coupling structure 9 to the second highest In the numerical aperture optical fiber 12, the two optical fiber connectors all use general-purpose FC/APC connectors, and the first end-face coupling structure 3 and the second end-face coupling structure 9 are all constructed as trapezoidal end-face coupling structures, which increases the silicon-based waveguide. The small mode spot radius solves the problem of mode matching and refractive index matching, thereby reducing the coupling loss.

As shown in Figure 1, the silicon-based optoelectronic chip 1 is fabricated by CSiP180Al active flow technology, based on SOI substrate, 2μm buried oxide (BOX) and 220nm top silicon. After testing, the overall loss of the dynamic polarization controller based on the silicon-based optoelectronic chip 1 is 5.35dB, and the end-face coupling loss is 2dB, which is far lower than the loss of other types of dynamic polarization controllers in the market.

As shown in Figure 2, the first end-face coupling structure 3 and the second end-face coupling structure 9 are composed of a silicon waveguide with a length of 400 μm, a width of 0.14 μm at one end, a width of 0.45 μm at the other end, and a thickness of 0.22 μm. One end with a width of 0.14 μm is located at the edge of the silicon-based optoelectronic chip 1, the distance between the first end-face coupling structure 3 and the second end-face coupling structure 9 is 127 μm, and the first high numerical aperture optical fiber 11 and the second high numerical aperture optical fiber 12 are both The distance between the first high numerical aperture optical fiber 11 and the first end face coupling structure 3 is optically coupled, and after the second high numerical aperture optical fiber 12 is optically coupled to the second end face coupling structure 9, it is cured by ultraviolet glue The two are packaged together; the first polarization rotating beam splitter 4 and the second polarization rotating beam splitter 8 are respectively connected to the 0.45 μm end of the first end coupling structure 3 and the second end coupling structure 9 .

The first polarization rotating beam splitter 4, the first polarization control structure 5, the second polarization control structure 6, the third polarization control structure 7, and the first polarization control structure 9 are sequentially connected between the first end surface coupling structure 3 and the second end surface coupling structure 9. Two polarization rotating beam splitters 8 .

Wherein, the first polarization control structure 5 includes a first electrically controlled phase shifter 15 and a second electrically controlled phase shifter 16, and the first electrically controlled phase shifter 15 and the second electrically controlled phase shifter 16 can realize 0° polarization Control function, the first electrically controlled phase shifter 15 is powered by the first pad 24 and the second pad 25, the second electrically controlled phase shifter 16 is powered by the third pad 23 and the second pad 25, and the pad 25 is a common terminal; the second polarization control structure 6 includes a first 50/50 coupler 17, a third electrically controlled phase shifter 18, a fourth electrically controlled phase shifter 19 and a second 50/50 coupler 20, the first Electronically controlled phase shifter 15, first 50/50 coupler 17, third electrically controlled phase shifter 18, fourth electrically controlled phase shifter 19, second 50/50 coupler 20 and sixth electrically controlled phase shifter 22 can realize the 45° polarization control function, the third electrically controlled phase shifter 18 is powered by the fourth pad 27 and the fifth pad 28; the fourth electrically controlled phase shifter 19 is powered by the sixth pad 26 and the fifth pad 28 power supply, the fifth pad 28 is a common terminal; the third polarization control structure 7 includes a fifth electrically controlled phase shifter 21 and a sixth electrically controlled phase shifter 22, the fifth electrically controlled phase shifter 21 and the sixth electrically controlled phase shifter The phase shifter 22 can realize the 0° polarization control function, the fifth electrically controlled phase shifter 21 is powered by the seventh pad 30 and the eighth pad 31; the sixth electrically controlled phase shifter 22 is powered by the ninth pad 29 and The eighth pad 31 supplies power, and the eighth pad 31 is a common terminal.

In Jones calculus, the stressed fiber can be expressed as two transformation matrices M0 and M45, as shown in formula (1):

α and β are the delayed phases caused by the birefringence of the stressed fiber; i represents the imaginary part; e represents the exponential form;

Then the three polarization-locked structures are described by the Jones matrix product as:

α, β and γ are the delayed phases caused by the birefringence of the stressed fiber; i represents the imaginary part; e represents the exponential form;

The matrix M45 can be transformed into a matrix of 50/50 couplers and the product of a matrix of M0 type and another matrix of 50/50 couplers, as shown in equation (3)

In the formula, β represents the phase delay; i represents the imaginary part; e represents the exponential form;

Therefore, the three transformation matrices of 0°/45°/0° are transformed into an equivalent waveguide structure on a silicon-based optoelectronic chip, as shown in Figure 1, using a parallel waveguide-controlled phase shifter to form a dual-channel polarization control device. Wherein the first electronically controlled phase shifter 15 and the second electrically controlled phase shifter 16 are used to generate α phase delay; the third electrically controlled phase shifter 18 and the fourth electrically controlled phase shifter 19 are used to generate β phase delay ; The fifth electronically controlled phase shifter 21 and the sixth electronically controlled phase shifter 22 are used to generate γ phase delay. This can increase the flexibility of the control method, realize the precise control of the phase, and make it easier to reset when the phase reaches saturation.

The first polarization rotating beam splitter 4 is composed of the first polarization rotating part 34 and the first polarization splitting part 35; the first polarization rotating part 34 is composed of the first part of the etched waveguide 49 and the first half of the first transition waveguide 50; the first The polarization beam splitting part 35 is composed of the second half of the first transition waveguide 50 and the first adiabatic waveguide 51; in the first polarization rotation beam splitter 4, the propagation direction of light is from left to right, and the light first passes through the first polarization rotation structure 34 , and then passes through the first polarization beam splitting part 35 .

The second polarization rotating beam splitter 8 is composed of the second polarization splitting part 36 and the second polarization rotating part 37; the second polarization splitting part 36 is composed of the second half of the second transition waveguide 53 and the second adiabatic waveguide 54; The second polarization rotation part 37 is composed of the second part of the etched waveguide 52 and the first half of the second transition waveguide 53; in the second polarization rotation beam splitter 8, the propagation direction of light is from right to left, and the light first passes through the second polarization The beam splitting part 36 then passes through the second polarization rotating part 37 .

As shown in Figures 3 and 4, when the light enters the silicon-based optoelectronic chip 1 from the first end face coupling structure 3, the light field of any polarization state entering the first polarization rotating beam splitter 4 is divided into the fundamental mode of the TM mode The light field TM0 and the fundamental mode light field TE0 of the TE mode, wherein the TMO mode light field is transformed into the TE mode high-order mode light field TE1 through the first polarization rotation part 34, and the TE0 mode light field does not convert; then the TE1 mode light field and the TE0 The mode light field enters the first polarization beam splitting part 35, and the TE0 mode light field is output along the first transition waveguide 50 without mode conversion, and is output from the port of the first transition waveguide 50 of the first polarization rotating beam splitter 4, TE1 The mode light field is coupled into the first adiabatic waveguide 51 from the first transitional waveguide 50, output from the port of the first adiabatic waveguide 51 of the first polarization rotating beam splitter 4, and the mode is converted into TE0, and is transmitted from the first polarization rotating beam splitter 4 outputs two beams of light whose polarization is both in TE0 mode; after passing through three polarization locking structures, the light field of two beams of TE0 mode output from the third polarization control structure 7 enters the second polarization rotating beam splitter 8, The light coming out from the sixth electronically controlled phase shifter 22 enters the second transition waveguide 53, the light coming out from the fifth electronically controlled phase shifter 21 enters the second adiabatic waveguide 54, and the second transition waveguide 53 The light in the TE0 mode is still transmitted along the second transition waveguide 53 in the TE0 mode and the mode does not change, and the light in the TE0 mode in the second adiabatic waveguide 54 is coupled from the second adiabatic waveguide 54 to the second polarized beam splitting part 36 In the second transition waveguide 53 and the mode is converted into a TE1 mode, the two beams are combined into one beam, and then enter the second polarization rotation part 37, and the second polarization rotation part 37 converts the TE1 mode into a TMO mode, and the TE0 mode does not convert, so that The TMO mode and the TE0 mode are output from the second polarization rotating beam splitter 8 to the second end-face coupling structure 9 .

The combination of the first end surface coupling structure 3 and the first polarization rotating beam splitter 4 can replace the two-dimensional grating input structure, couple light into the silicon-based optoelectronic chip 1, and rotate the polarization state, so that The light field with any polarization state enters the polarization-locked structure in TE0 mode. The combination of the second polarization rotating beam splitter 8 and the second end-face coupling structure 9 can replace the two-dimensional grating output structure, and combine the locked arbitrary polarization state light fields of the locked two TE0 modes into one One beam converts part of the light field into TMO mode, and outputs it from the silicon-based optoelectronic chip 1 in two modes of TMO mode and TE0 mode.

In order to make the waveguide length between the first polarization rotating beam splitter 4 and the first 50/50 coupler the same, a first compensation waveguide 32 is connected between the first polarization control structure 5 and the second polarization control structure 6; in order to make The length of the waveguide between the second 50/50 coupler 20 and the second polarization rotating beam splitter 8 is the same, and the second compensation waveguide 33 is connected between the second polarization control structure 6 and the second polarization rotating beam splitter 8 .

The light fields of the two TE0 modes output from the first polarization rotating beam splitter 4 sequentially enter the first polarization control structure 5, the second polarization control structure 6 and the third polarization control structure 7; the first polarization control structure 5 , the second polarization control structure 6, and the third polarization control structure 7 all use an electronically controlled phase shifter to generate a phase delay. The phase of the electronically controlled phase shifter has a definite functional relationship with the applied voltage, and the phase delay can be controlled by controlling the voltage Quantity is deterministically controlled. During the polarization control process, after the voltage of the electronically controlled phase shifter reaches saturation, the electronically controlled phase shifter can be reset by adding or subtracting V _2π voltage. Each control structure adopts a parallel wave conductive phase shifter for phase control, and has two control ports, so that the entire silicon-based optoelectronic chip 1 has three pairs of six control ports in total. During the polarization control process, only one of each pair of electronically controlled phase shifters is used, and when it reaches saturation, the other one of the control structure can be used, and at the same time, the current saturated electronically controlled phase shifter is reset.

As shown in FIG. 5 , the single-mode optical fiber, high numerical aperture optical fiber and silicon-based optoelectronic chip 1 used in this embodiment are suitable for 0-band and C-band communication. A 1550nm fiber pigtail DFB laser 38 is used to generate a continuous beam, and a variable optical attenuator 39 is used to adjust the beam intensity to adjust the beam intensity required by the experiment at any time. The beam is split by a 50/50 beam splitter 40, one of which is connected to a first power meter 41 for detecting the optical power of the input light, and the other is connected to a manual polarization controller 42 for adjusting the polarization state of the input light. Then the single-mode optical fiber coming out from the manual polarization controller 42 is converted into the first high numerical aperture optical fiber 11 through the first optical fiber connector 13 through the single-mode optical fiber, and then the first high numerical aperture optical fiber 11 and the edge of the silicon-based optoelectronic chip 1 The first end surface coupling structure 3 is coupled to couple light into the silicon-based optoelectronic chip 1 . Then output from the second end face coupling structure 9 through the dynamic polarization control system on the silicon-based optoelectronic chip 1, output to the second high numerical aperture optical fiber 12 through the second end face coupling structure 9, and then output to the second optical fiber through the single-mode optical fiber Connector 14. Therefore, the light passing through the silicon-based optoelectronic chip 1 is output to the polarization beam splitter 43 , and the light is divided into two paths, one of which is connected to the second power meter 44 and the other is connected to the photodetector 45 .

In the experiment, by using 25μm gold wires to bond the external PCB circuit board to the pads on the chip, in this way, the driving voltage is applied to the electronically controlled phase shifter on the dynamic polarization controller to change the voltage in the electronically controlled phase shifter. The amount of phase delay makes the polarization controller work normally, wherein the length of the electronically controlled phase shifter is 400 μm, and the resistance of the electronically controlled phase shifter is 2KΩ. By changing the voltage across the electronically controlled phase shifter, the output power can be changed. The expression where the voltage is converted into the power applied to the electronically controlled phase shifter is:

Among them, R represents the resistance of the electronically controlled phase shifter; P represents the output power of the electronically controlled phase shifter; V represents the voltage applied to the electronically controlled phase shifter.

However, there is a very good linear relationship between the thermal power and the phase shift of the electronically controlled phase shifter, which can realize precise control of the phase and speed up the locking speed of dynamic polarization control. Through the test, when the power of the electronically controlled phase shifter is added from 0mW to 50mW, the total phase shift generated is 3π, and the corresponding voltage should be added from 0V to 10V after conversion. As shown in Figure 6, the phase change and power ratio are linear relationship, so there is no need to use a high voltage greater than 10V for operation.

When performing dynamic polarization control, dynamic polarization control algorithms such as simulated annealing and gradient algorithm are often used to automatically lock the polarization of light. One path of light connected to the photodetector 45 is used for polarization locking and calculation of extinction ratio, and the light power at this end changes from maximum to minimum, so that the light of this path changes from a light-passing state to an extinction state, then the light power at this end is minimum. The voltage collected by the photodetector 45 can be collected by the receiving end 46 of the USB6259 acquisition card through the computer control terminal 47, and then the voltage at the output terminal 48 of the output terminal 48 of the USB6259 acquisition card is controlled by the simulated annealing algorithm to control the voltage on the silicon-based optoelectronic chip 1. Electronically controlled phase shifter is used to control, so that the light of this path is locked to the minimum value and reaches the state of extinction. Then the extinction ratio of the path light is obtained through data processing. One path of light connected to the second power meter 44 is used to calculate the extinction ratio. Before locking, adjust the manual polarization controller 42 to minimize the power of the path, so that the path reaches the extinction state, and then perform polarization locking. After locking, the power of this end is the maximum , read the maximum and minimum values from the second power meter 44, and the extinction ratio at this end can be obtained.

Experimental results: In this experiment, a 1mW 1550nm communication band laser is coupled into the dynamic polarization controller through a lens fiber, path 1 is connected to the photodetector 35, path 2 is connected to the second power meter 44, and the manual polarization is adjusted The controller 42 makes the path 1 maximum pass light about 300 μW (power from large to small), the result after polarization locking is shown in Figure 7, the locking result shows that when using a fixed step size of 0.01V, the dynamic polarization of the present invention The controller can lock the extinction ratio of the road light to be above 25dB, and the extinction ratio of about 12dB at the beginning of the locking result is due to the saturation of the photodetector 45 .

To sum up, it can be concluded that coupling light into the silicon-based optoelectronic chip 1 through the end-face coupling structure 3 reduces the loss of light to 2dB when it enters the chip from an external high-NA optical fiber, and after using the polarization rotating beam splitter, the dynamic After the polarization controller is locked, the dynamic extinction ratio can reach more than 25dB.

In summary, the theoretical analysis and experimental verification prove that the present invention has the effect of smaller coupling loss and larger polarization extinction ratio compared with the existing dynamic polarization controller based on silicon-based optoelectronic chips. At the same time, after adding the first polarization rotating beam splitter 4, it can better ensure that the modes of light entering the dynamic polarization controller are all TE0 modes, and the design of the input and output ends of the end-face coupling structure on the same side can be packaged in the later stage. etc. are more convenient than the grating coupling structure.

The main features and advantages of the present invention have been shown and described above. For those skilled in the art, it is obvious that the specific implementation of the present invention is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or basic features of the present invention. Under the circumstances, the creative ideas and design ideas of the present invention can be realized in other specific forms, which should equally belong to the scope of protection disclosed in the technical solutions of the present invention. Accordingly, the embodiments should be regarded in all points of view as exemplary and not restrictive, the scope of the invention being defined by the appended claims rather than the foregoing description, and it is therefore intended that the scope of the invention be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in the present invention.

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only includes an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art.

Claims (8)

1. A dynamic polarization controller based on a silicon-based optoelectronic chip, characterized in that: a silicon-based optoelectronic chip (1) is included, and the side of the silicon-based optoelectronic chip (1) is connected with an input-output structure (2), so The silicon-based optoelectronic chip (1) is respectively provided with a first end-face coupling structure (3) connected to the input end of the input-output structure (2) and a second end-face coupling structure connected to the output end of the input-output structure (2). (9), the first polarization rotating beam splitter (4), the first polarization control structure (5), the second A polarization control structure (6), a third polarization control structure (7), and a second polarization rotating beam splitter (8). 2. A kind of dynamic polarization controller based on a silicon-based optoelectronic chip according to claim 1, characterized in that: the input-output structure (2) includes an array optical fiber FA port (10), a first optical fiber connector ( 13) and the second optical fiber connector (14), the array fiber FA port (10) includes the first high numerical aperture optical fiber (11) as the input end and the second high numerical aperture optical fiber (12) as the output end, so One end of the first high numerical aperture optical fiber (11) is connected to the first end-face coupling structure (3), and the other end is connected with a first optical fiber connector (13) through a single-mode optical fiber, and the second high numerical aperture optical fiber (12) One end is connected to the second end-face coupling structure (9), and the other end is connected to a second optical fiber connector (14) through a single-mode optical fiber. 3. A kind of dynamic polarization controller based on a silicon-based optoelectronic chip according to claim 1, characterized in that: the first end face coupling structure (3) and the second end face coupling structure (9) are both configured as trapezoidal Body-to-face coupling structure. 4. A kind of dynamic polarization controller based on a silicon-based optoelectronic chip according to claim 1, characterized in that: the first polarization control structure (5) includes a first electronically controlled phase shifter (15) and The second electrically controlled phase shifter (16), the first electrically controlled phase shifter (15) and the second electrically controlled phase shifter (16) can realize the 0 ° polarization control function; the second polarization control structure ( 6) comprising a first 50/50 coupler (17), a third electrically controlled phase shifter (18), a fourth electrically controlled phase shifter (19) and a second 50/50 coupler (20), the The first electronically controlled phase shifter (15), the first 50/50 coupler (17), the third electrically controlled phase shifter (18), the fourth electrically controlled phase shifter (19), the second 50/50 coupling The device (20) and the sixth electronically controlled phase shifter (22) can realize the 45° polarization control function; the third polarization control structure (7) includes the fifth electrically controlled phase shifter (21) and the sixth electrically controlled The phase shifter (22), the fifth electrically controlled phase shifter (21) and the sixth electrically controlled phase shifter (22) can realize the 0° polarization control function. 5. A kind of dynamic polarization controller based on a silicon-based optoelectronic chip according to claim 4, characterized in that: the first electronically controlled phase shifter (15) consists of a first pad (24) and a second The pad (25) supplies power; the second electrically controlled phase shifter (16) is powered by the third pad (23) and the second pad (25), and the second pad (25) is a common terminal; The third electrically controlled phase shifter (18) is powered by the fourth pad (27) and the fifth pad (28); the fourth electrically controlled phase shifter (19) is powered by the sixth pad (26) and the fifth pad (28). Five pads (28) supply power, and the fifth pad (28) is a common terminal; The fifth electrically controlled phase shifter (21) is powered by the seventh welding pad (30) and the eighth welding pad (31); the sixth electrically controlled phase shifter (22) is powered by the ninth welding pad (29) and the The eight pads (31) supply power, and the eighth pad (31) is a common terminal. 6. A kind of dynamic polarization controller based on a silicon-based optoelectronic chip according to claim 1, characterized in that: the first polarization rotating beam splitter (4) consists of a first polarization rotating part (34) and a first polarization The beam splitting part (35) is formed; the first polarization rotation part (34) is composed of the first part of the etched waveguide (49) and the first half of the first transition waveguide (50); the first polarization beam splitting part (35) is composed of the first part A second half of the transition waveguide (50) and the first adiabatic waveguide (51); The second polarization rotation beam splitter (8) is made up of the second polarization beam splitting part (36) and the second polarization rotation part (37); the second polarization beam splitting part (36) is formed by the second transition waveguide (53) part and the second heat insulation waveguide (54); the second polarization rotation part (37) is composed of the second partially etched waveguide (52) and the first half of the second transition waveguide (53). 7. A kind of dynamic polarization controller based on a silicon-based optoelectronic chip according to claim 1, characterized in that: said first polarization control structure (5) and the second polarization control structure (6) are connected with A second compensation waveguide (33) is connected between the first compensation waveguide (32); the second polarization control structure (6) and the second polarization rotation beam splitter (8). 8. A control method for applying a dynamic polarization controller based on a silicon-based optoelectronic chip as claimed in claim 1, characterized in that: comprising the following steps: Step 1: The light field of any polarization state in the external single-mode optical fiber is input to the first high numerical aperture optical fiber (11) through the first optical fiber connector (13) in the input-output structure (2) for mode spot conversion, and the mode spot After matching and transmitting to the first end-face coupling structure (3), the mode spot is further transformed and transmitted to the first polarization rotating beam splitter (4), and any polarization state light entering the first polarization rotating beam splitter (4) The field is divided into the fundamental mode light field TM0 of the TM mode and the fundamental mode light field TE0 of the TE mode, wherein the TM0 mode light field is converted into the higher-order mode light field TE1 of the TE mode through the first polarization rotation part (34), and the TE0 mode light field is not Conversion occurs; then the TE1 mode light field and the TE0 mode light field enter the first polarization beam splitting part (35), the TE0 mode light field is transmitted along the first transition waveguide (50) and the mode does not convert, from the first polarization rotation The first transition waveguide (50) port output of the beam splitter (4), the TE1 mode light field is coupled into the first adiabatic waveguide (51) from the first transition waveguide (50), and from the first polarization rotating beam splitter (4 ) of the first adiabatic waveguide (51) port output, and the mode is converted to TE0, and the modes of the two beams of light output from the first polarization rotating beam splitter (4) are both TE0; Step 2: The light fields of the two beams of TE0 mode output from the first polarization rotating beam splitter (4) enter the first polarization control structure (5), the second polarization control structure (6) and the third polarization control structure in sequence In (7): the first polarization control structure (5), the second polarization control structure (6), and the third polarization control structure (7) all use an electrically controlled phase shifter to generate a phase delay; Step 3: After passing through the three polarization locking structures, the light field of the two beams of TE0 mode output from the third polarization control structure (7) enters the second polarization rotating beam splitter (8), and from the sixth electrically controlled phase The light coming out of the shifter (22) enters the second transition waveguide (53), the light coming out of the fifth electrically controlled phase shifter (21) enters the second adiabatic waveguide (54), and the second transition waveguide The light of the TE0 mode in (53) is still transmitted along the second transition waveguide (53) in the TE0 mode and the mode does not change, and the light of the TE0 mode in the second adiabatic waveguide (54) is in the second polarization beam splitting part (36) Coupled into the second transitional waveguide (53) from the second adiabatic waveguide (54) and the mode is converted into TE1 mode, the two beams are combined into one beam, and then enter the second polarization rotation part (37), the second polarization rotation part (37) Convert the TE1 mode to the TM0 mode, and the TE0 mode does not convert, and then the light of the two modes of TM0 and TE0 is input into the second end-face coupling structure (9), and then output to the input and output after mode spot conversion and matching In the second high numerical aperture optical fiber (12) in the structure (2), the mode spot is converted again and then output through the second optical fiber joint (14).