CN116819685A - Polarization independent integrated tunable dispersion compensation chip - Google Patents
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Abstract
A polarization independent integrated tunable dispersion compensation chip based on a switch cascading antisymmetric grating is characterized in that: the chip comprises a polarization independent multistage serial cascade optical switch and a polarization independent antisymmetric grating with exponentially increased dispersion compensation quantity. The grating is formed by ridge waveguide with antisymmetric sawtooth stripes on the side wall, and the light is polarized and rotated after being reflected by the grating (TE polarization is changed into TM polarization, TM polarization is changed into TE polarization), so that the grating has the same dispersion compensation for different TE and TM polarization inputs. And whether the anti-symmetric grating is passed or not is selected through state switching of the multistage serial cascade optical switch, so that switching of different dispersion compensation amounts is realized. The invention can realize the large-scale adjustable polarization independent dispersion compensation, has the advantages of insensitive polarization, small size, high integration level, low power consumption, simple structure, easy expansion and the like, can compensate the optical fiber dispersion in the scenes of optical communication, optical interconnection of a data center and the like, and has wide application prospect.
Description
Technical Field
The invention belongs to the field of optical signal processing, and particularly relates to a polarization independent integrated tunable dispersion compensation chip.
Background
In optical communication systems, the presence of fiber dispersion has always affected the quality of optical signal transmission. Optical fiber dispersion causes different delays of optical signals with different wavelengths, so that a phenomenon of time domain broadening occurs after a certain distance is transmitted, and the high-quality transmission distance of the optical signals is limited. How to realize dispersion compensation of an optical fiber has been the focus of researchers.
With the rapid development of the Internet and 5G, the requirements of information data calculation and storage are continuously improved, the scale of a global data center is expanded, and simultaneously, higher requirements are put on the total data quantity which can be transmitted by an optical fiber in the same time. In an optical communication system, dispersion compensation of an optical fiber is an indispensable part because the quality of a signal transmitted in a link is deteriorated due to the presence of dispersion of the optical fiber, and the optical power in the link has to be increased in order to achieve the same transmission error rate, which may cause the generation of nonlinear effects; in addition, the quality of the signal transmitted in the link decreases with the increase of the optical fiber length, and after the optical fiber length reaches a certain level (for example, 20 km), the signal is difficult to distinguish, and how to increase the optical power is not helpful, which seriously affects the high-quality transmission of the data in the optical communication system. Dispersion compensation of an optical fiber solves the above two problems, and therefore, in an optical communication system, dispersion compensation of an optical fiber is an important part. In an optical communication system, the connection distances of optical fibers between different nodes are not equal, so that in practical application, one key point of the optical fiber dispersion compensation design is the adjustability of the compensation amount along with the change of the optical fiber length. In addition, the polarization insensitive design has higher practical application value.
The traditional dispersion compensation optical fiber can only compensate the dispersion of the fixed length optical fiber, and cannot realize the function of adjusting the dispersion compensation amount. The current tunable dispersion compensator is mostly realized by discrete devices, the size of the devices is large, the power consumption is high, the integration scheme is relatively complex, and the tunable dispersion compensator is usually designed for only one polarization state and has high polarization sensitivity. Therefore, the integrated tunable dispersion compensation chip which has small size, insensitive polarization, low power consumption, simple structure, easy expansion, high stability and large-scale adjustable dispersion compensation amount is researched, and has high practical application value.
A cascaded adjustable silicon-based Bragg grating dispersion compensator (patent publication No. CN 112684541) comprises an input end straight waveguide, a multi-stage optical switch, a multi-stage Bragg grating dispersion compensator, all stages of straight waveguides and an output end straight waveguide, wherein the multi-stage optical switches are connected in series through the straight waveguides and the Bragg grating dispersion compensator, the input end of a first-stage optical switch is connected with the input end straight waveguide, and the output end of a last-stage optical switch is connected with the output end straight waveguide. In the structure, the grating waveguide adopts symmetrical gratings, namely geometric structures at two sides of the grating waveguide are mirror symmetry, and TE and TM polarized inputs have different reflection spectrums and dispersion compensation due to strong polarization correlation of the silicon waveguide; the adopted optical switch also has polarization sensitivity, and the two polarization inputs cannot realize consistent optical path switching. Thus, the Bragg grating dispersion compensator can only handle a single polarization. In practical optical communication systems, the input polarization is random and in constant variation, so that dispersion compensation of an input signal of arbitrary polarization cannot be achieved with the bragg grating dispersion compensator described above.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a polarization independent integrated tunable dispersion compensation chip based on a switch cascading anti-symmetric grating,
in order to achieve the above object, the technical solution of the present invention is as follows:
the polarization independent integrated tunable dispersion compensation chip comprises an input end straight waveguide, an output end straight waveguide and all levels of straight waveguides, and is characterized by further comprising a multi-level polarization independent optical switch and a polarization independent antisymmetric grating with exponentially increased multi-level dispersion compensation quantity; the two input ports and the two output ports of the two adjacent two-stage optical switches are respectively connected with the straight waveguide by the polarization-independent antisymmetric grating; by switching the optical switch, the optical signals are led to take different paths, thereby realizing the adjustment of dispersion compensation quantity;
the polarization independent anti-symmetric grating has an asymmetric structure in the up-down and left-right directions, the zigzag protrusions at the edges of the two sides of the waveguide are distributed in an anti-symmetric manner, and the zigzag protrusions are concave towards the inner side while protruding towards the outer side; meanwhile, the waveguide adopts a ridge waveguide structure with a slab layer, namely, the cross section of the waveguide is in a convex structure, and the width of the grating waveguide is in linear change in the light propagation direction and is used for controlling the dispersion compensation quantity of the grating.
After the optical signal is input through the input end straight waveguide, the optical signal is selectively connected with a next-stage polarization independent antisymmetric grating or connected with a next-stage straight waveguide through the polarization independent optical switch when passing through each polarization independent optical switch; the input optical signals with different wavelengths are reflected at different positions of the polarization-independent antisymmetric grating, so that different delay amounts are obtained, and flat dispersion is formed in a certain bandwidth; the grating waveguide structure has left-right antisymmetry and up-down asymmetry, and the input light can generate polarization rotation after being reflected by the grating, namely, the input TE polarized light is changed into TM polarization after being reflected, the input TM polarized light is changed into TE polarization, and the polarization rotation cannot be realized in the conventional grating; different dispersion amounts can be obtained by changing the gradient of the width change of the grating waveguide, and the dispersion amounts are input to a polarization independent optical switch at the subsequent stage after compensation.
The optical switch can be a Mach-Zehnder interferometer or a micro-ring resonator structure and has the characteristic of insensitive polarization; for an optical switch based on a Mach-Zehnder interferometer structure, the switch is composed of two 3dB optical splitters and an upper adjusting arm and a lower adjusting arm, the 3dB optical splitters can be realized by structures such as a multimode interferometer or a directional coupler, the switching of the switch state from straight-through to cross can be realized by adjusting the phase difference of the upper arm and the lower arm of the switch, so that an output optical signal is switched from one port to the other port, the 3dB optical splitters and the phase shifters for adjusting the phase difference are all in polarization-independent designs, namely the optical splitters have the same optical splitting ratio for TE and TM polarization, and the phase shifters have the same phase shifting efficiency; for an optical switch based on a micro-ring resonator structure, the switch is composed of two sections of straight waveguides and one or more micro-ring resonators, the coupling area of the straight waveguides and the micro-ring has the characteristic of being insensitive to polarization, namely, the coupling area has the same coupling coefficient to TE and TM polarization, and the micro-ring resonators comprise polarization rotators, so that TE can be converted into TM and TM can be converted into TE, and therefore, half TE and half TM polarization exist in micro-rings when different polarizations are input, and the design of being insensitive to polarization is realized. By adjusting the micro-ring resonant wavelength, the micro-ring resonator can be in a straight-through or download state, so that the switching of signals between output ports is realized as well.
The anti-symmetric grating reflects input optical signals with different wavelengths at different positions of the grating, so that different delay amounts are obtained, and flat dispersion is formed in a certain bandwidth. The polarization rotation can occur after the reflection of the chirped grating in different polarization states, TE can be changed into TM, and TM can be changed into TE, so that the same dispersion can be obtained by the grating in different polarization states, and the polarization insensitivity function can be realized. By varying the grating length, different amounts of dispersion can be obtained.
The waveguide structures adopted by the optical switch and the anti-symmetric grating can be composed of ridge waveguides; the chip is made of silicon, silicon nitride, silicon dioxide, indium phosphide, thin film lithium niobate and the like.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention integrates all devices corresponding to different functional modules on the same chip, has the advantages of small chip size, insensitive polarization, high integration level, low power consumption, high stability, simple and easily-expanded structure, low power consumption, large-scale adjustable dispersion compensation amount and the like, is beneficial to reducing the cost, is suitable for mass production, and has high application value in optical communication and optical interconnection.
2. The invention can realize the digital adjustment of the dispersion compensation quantity by adjusting the states of each optical switch, the step length of the dispersion compensation is determined by the first-stage dispersion compensation quantity, the dispersion compensation adjustment range is determined by the cascade stage number of the switch, and the step length and the stage number can be designed according to different requirements, thereby meeting different dispersion compensation application requirements.
3. The chip structure of the invention is easy to expand, and the chip control complexity is linearly increased along with the number of the cascaded switches. The structure is characterized in that a polarization independent cascade optical switch is combined with a polarization independent antisymmetric grating, and the wide-range adjustment of chromatic dispersion can be realized simultaneously for different polarization states by utilizing the switching characteristic of the optical switch and the chromatic dispersion compensation characteristic of the grating.
4. The waveguide grating structure in the dispersion compensation chip has left-right antisymmetric characteristic and up-down asymmetric characteristic, and input light is subjected to polarization rotation when reflected in the grating, so that the optical path lengths of TE and TM input polarization are the same, and polarization independent dispersion compensation can be realized. The polarization independent dispersion compensation can solve the influence caused by the change of input polarization in the actual optical communication system, so that the system is more stable and reliable.
Drawings
FIG. 1 is a schematic diagram of the overall structure of a polarization independent integrated tunable dispersion compensation chip based on a switch cascade antisymmetric grating of the present invention.
Fig. 2 is a schematic diagram of an antisymmetric grating structure of a polarization independent integrated tunable dispersion compensation chip based on a switch cascade antisymmetric grating, wherein (a) antisymmetric stripe protrusions are distributed on two sidewalls of a grating waveguide and (b) cylindrical protrusions are distributed on two sidewalls of the grating waveguide.
Fig. 3 is a schematic diagram of a 2×2 polarization independent optical switch structure of a polarization independent integrated tunable dispersion compensation chip based on a switch cascade antisymmetric grating according to the present invention, where (a) is an optical switch based on a mach-zehnder interferometer structure, and (b) is an optical switch based on a micro-ring resonator structure.
FIG. 4 shows the simulation results of the delay amounts and the average dispersion compensation amounts of eight dispersion compensation states in the embodiment of the 3-bit dispersion compensation chip based on the polarization independent integrated tunable dispersion compensation chip of the switch cascaded antisymmetric grating, wherein (a) is the average dispersion compensation value of 8 states of delay lines (b) of total 8 states gradually adjusted to 7ΔD with ΔD as step length from 0
Fig. 5 is a simulation result of the grating delay amount and the average dispersion compensation amount of the polarization independent integrated tunable dispersion compensation chip based on the switch cascade antisymmetric grating according to the present invention along with the change of the grating length.
FIG. 6 shows the results of the simulation of the delay and dispersion compensation of each stage of grating in the embodiment of the 3-bit dispersion compensation chip based on the polarization independent integrated tunable dispersion compensation chip of the switch cascade antisymmetric grating, wherein (a) is the result of the simulation of the respective delay of the 3-bit antisymmetric grating of the 3-bit tunable dispersion compensation chip, and (b) is the result of the simulation and exponential fit of the dispersion compensation of each stage.
Detailed Description
In order to further clarify the objects, technical solutions and core advantages of the present solution, the present invention will be described in further detail below with reference to the drawings and examples. The present embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation and operation procedures are given, but the protection scope of the present invention is not limited to the following examples.
FIG. 1 is a schematic diagram of the overall structure of a polarization independent integrated tunable dispersion compensation chip based on a switch cascade antisymmetric grating of the present invention. The method is mainly divided into two parts according to the functional characteristics: polarization independent optical switches 101 to 104 and polarization independent antisymmetric gratings 105 to 107 whose dispersion compensation amount increases exponentially. Each optical switch has two working states of direct connection and cross, the direct connection state indicates that an optical signal can be output from a port on the same side as an input port, the cross state indicates that an optical signal can be output from a port on the opposite side as the input port, for example, an optical signal is input from an upper port, if the optical signal is output from the upper port, the optical signal is in the direct connection state, and if the optical signal is output from the upper port, the optical signal is output from a lower port, the optical signal is in the cross state.
The antisymmetric grating structure is shown in fig. 2, in which (a) two sidewalls of the grating waveguide of the graph are distributed with antisymmetric stripe-shaped protrusions, and (b) two sidewalls of the grating waveguide of the graph are distributed with cylindrical protrusions, and the cylinders can be close to the sidewalls of the waveguide or have a certain interval for controlling the coupling coefficient, the adopted waveguide is a ridge waveguide with a slab layer, the width of the waveguide is gradually reduced along the propagation direction, and the grating has the same reflection spectrum characteristic on the input TE and TM polarization.
The 2×2 polarization independent optical switch structure is shown in fig. 3, where (a) is an optical switch based on a mach-zehnder interferometer structure, and (b) is an optical switch based on a micro-ring resonator structure, and the 2×2 optical switch structure has polarization insensitive characteristics. For optical switches based on mach-zehnder interferometer structures, the switch contains 2 polarization rotators and 4 phase shifters in addition to the 3dB splitter and the conditioning arm. The polarization independent nature of the switch is achieved by designing a polarization insensitive 3dB splitter and a polarization insensitive phase shifter. For the splitter, the 3dB splitter in the switch has the same splitting ratio for TE and TM polarizations; for phase shifters, the polarization rotator on the switching arm is located in the center of the arm, with 1 phase shifter in front of and behind it. The polarization rotator can convert TE into TM, and TM into TE, so that half TE and half TM polarization exist on the two adjusting arms when different polarization states are input, and then the simultaneous phase shifting of the two polarization states can be realized by simultaneously adjusting 2 phase shifters on one adjusting arm, so that the design of the phase shifter insensitive to polarization is realized. For optical switches based on micro-ring resonator structures, the switch is made up of two sections of straight waveguides and micro-ring resonators, and polarization independent characteristics are achieved by designing polarization insensitive coupling regions and polarization insensitive micro-ring resonators. For the coupling region, the coupling region of the straight waveguide and the micro-ring has the same coupling coefficient for TE and TM polarization, so that polarization independent coupling can be realized; for the micro-ring, 2 polarization rotators are symmetrically distributed on the micro-ring, TE can be converted into TM, TM can be converted into TE, so that when different polarization states are input, half TE and half TM are polarized in the micro-ring respectively, and then the phase shifting of TE and TM on the ring can be simultaneously realized through adjusting 2 phase shifters on the ring, so that the function of insensitivity of polarization is realized.
The optical signal to be compensated is input from any input port of the first-stage polarization independent optical switch 101, and when the input optical signal passes through the first-stage polarization independent optical switch 101, the input optical signal can be output from any output port by changing the voltage on a certain adjusting arm or micro-ring phase shifter of the optical switch.
When an input optical signal is output from a lower output port of the first-stage polarization independent optical switch 101, the signal is directly input to a lower input port of the second-stage polarization independent optical switch 102 after passing through a section of straight waveguide, does not pass through the first-stage polarization independent antisymmetric grating 105, and does not generate dispersion compensation, and the state is recorded as a reference path; when an input optical signal is output from the upper output port of the first-stage polarization independent optical switch 101, the signal passes through the first-stage polarization independent anti-symmetric grating 105, and optical signals with different wavelengths are reversely coupled at different positions of the anti-symmetric grating 105, so that the delays of the signals with different wavelengths are different, and a certain dispersion compensation amount delta D is generated. The output optical signal passing through the first-stage polarization independent antisymmetric grating 105 is then input from the upper input port to the second-stage polarization independent optical switch 102, which is referred to as the compensation path.
The second stage polarization independent optical switch 102 may then also effect switching of an optical signal from either input port to either output port by applying a voltage to a certain tuning arm or micro-ring. When the optical signal is output from the lower output port of the second-stage polarization independent optical switch 102, the signal is input to the lower input port of the next-stage polarization independent optical switch 103 after passing through only one section of straight waveguide, and dispersion compensation is not generated; when an optical signal is output from the upper output port of the second-stage polarization independent optical switch 102, the signal passes through the second-stage polarization independent antisymmetric grating 106, and the dispersion compensation amount of the second-stage antisymmetric grating 106 is twice that of the first-stage, so that a dispersion compensation amount of 2Δd is generated for the optical signal. The optical signal is then output from the output end of the second-stage polarization independent antisymmetric grating 106 and enters the upper input port of the third-stage polarization independent optical switch 103.
Subsequent analysis of the optical switch state and the amount of introduced dispersion compensation is similar to that described above, except that the third stage polarization independent antisymmetric grating 107 can introduce a maximum amount of dispersion compensation of 4Δd. Finally, by adjusting the voltage on a certain tuning arm or micro-ring of the fourth stage polarization independent optical switch, an optical signal will be output from a certain port of the fourth stage polarization independent optical switch.
In fig. 1, an antisymmetric grating structure is adopted, wherein grating saw teeth are distributed on two side walls of a waveguide in an antisymmetric way, the grating can realize conversion of polarization states, the input TE polarization is converted into TM polarization, the TM polarization is converted into TE polarization, and the specific structure of the polarization independent antisymmetric grating is shown in an enlarged view of a first-stage polarization independent dispersion compensation grating. The polarization rotation can be realized during reflection by adopting the grating with the anti-symmetrical waveguide side walls and adopting the ridge waveguide structure with the flat plate layer. For the structure shown in fig. 1, after an optical signal enters the grating from the upper output port of the previous stage polarization independent optical switch, the optical signal is divided into two paths by the polarization independent 2×2 coupler and enters the two polarization independent antisymmetric gratings with the same structure, the TE mode (or TM mode) in the waveguide is reflected at different positions of the grating and becomes the TM mode (or TE mode), so that the time delays experienced by the optical signals with different wavelengths are different, and then the two paths of reflected TM mode (or TE mode) optical signals are combined into one path by the polarization independent 2×2 coupler and then input to the upper input port of the next stage polarization independent optical switch. The input polarization state is TE mode or TM mode, and the same dispersion amount is generated after the input polarization state is reflected by the current first-stage polarization independent grating, so that polarization insensitive dispersion compensation is realized. The subsequent stages of the raster process are similar.
The device structure shown in fig. 1 is a 3-bit tunable dispersion compensation chip because of the common 3-level polarization independent antisymmetric grating. Because each optical switch has two working states of direct connection and cross connection, and the input optical signal can pass through the reference path or the compensation path by adjusting the states, the whole structure can realize 2 3 The amount of dispersion compensation is gradually adjusted from 0 to 7 Δd in Δd steps.Fig. 4 shows simulation results of the delay amounts and the average dispersion compensation amounts of the 3-bit tunable dispersion compensation chip in 8 different states, in which (a) corresponds to delay lines of total 8 states gradually adjusted from 0 to 7 Δd in a step size, and (b) corresponds to the average dispersion compensation value of the 8 states. The bandwidth of the grating is 2, and the average dispersion compensation calculation formula in the bandwidth range isWherein lambda is 1 = 1553.6 is the smallest wavelength in the bandwidth range, λ 2 = 1555.6 is the maximum wavelength within the bandwidth, τ 1 And τ 2 Respectively correspond to lambda 1 And lambda (lambda) 2 The delay amount at the wavelength is approximately linearly increased by the average dispersion compensation value under different states according to the simulation result, and the design requirement is met. For an N-bit adjustable dispersion compensation chip (N is a positive integer), the dispersion compensation quantity of the N-th stage based on the switch cascade anti-symmetric grating is delta D N ＝2 N-1 Δd. Therefore, the dispersion compensation amount of the N-bit tunable dispersion compensation chip can be gradually adjusted from 0 to (2) in a step of DeltaD N -1 ΔD, 2 altogether N A state.
In addition, the dispersion compensation amount step delta size Δd can be changed by designing the grating length of the first-order polarization independent antisymmetric grating 105. FIG. 5 shows simulation results of the delay amount and the average dispersion compensation amount introduced by chirped gratings of different periods, where N grating As the number of periods of the grating increases, the longer the grating is, and it can be seen that as the grating length increases linearly, the dispersion compensation value also increases approximately linearly. The structure of the subsequent polarization independent antisymmetric grating at each stage is similar to that of the first stage, and the dispersion compensation amount gradually increases exponentially. Fig. 6 (a) shows the simulation results of the respective delay amounts of 3-bit adjustable dispersion compensation chip and 3-level antisymmetric gratings, (b) shows the simulation and index fitting results of the dispersion compensation amounts of each level, and (b) shows that the average dispersion compensation amounts of the gratings of each level are exponentially changed to meet the design requirement. Meanwhile, the number of stages of the dispersion compensation chip can be changed according to the requirement. This allows flexible configuration of the dispersion compensation step size ΔD and the number of stages N, thereby realizingThe dispersion compensation function is widely and flexibly configured and adjustable.
In summary, the polarization independent integrated tunable dispersion compensation chip based on the switch cascade antisymmetric grating, which is realized by the invention, can realize flexibly configured large-scale tunable dispersion compensation, has the characteristics of small size, insensitive polarization, high integration level, low power consumption, good stability and the like, can play a key role in the scenes of optical communication, optical interconnection and the like, and has high practical application value.
Finally, it should be noted that the above is only a preferred embodiment of the present invention, and the present invention is not limited to 3-bit tunable dispersion compensation chips, as will be understood by those skilled in the art. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. The polarization independent integrated tunable dispersion compensation chip comprises an input end straight waveguide, an output end straight waveguide and all levels of straight waveguides, and is characterized by further comprising a multi-level polarization independent optical switch and a polarization independent antisymmetric grating with exponentially increased multi-level dispersion compensation quantity; the two input ports and the two output ports of the two adjacent two-stage optical switches are respectively connected with the straight waveguide by the polarization-independent antisymmetric grating; by switching the optical switch, the optical signals are led to take different paths, thereby realizing the adjustment of dispersion compensation quantity;
the polarization independent anti-symmetric grating has an asymmetric structure in the up-down and left-right directions, the zigzag protrusions at the edges of the two sides of the waveguide are distributed in an anti-symmetric manner, and the zigzag protrusions are concave towards the inner side while protruding towards the outer side; meanwhile, the waveguide adopts a ridge waveguide structure with a slab layer, namely the cross section of the waveguide presents a 'convex' shape structure, and the width of the grating waveguide presents linear change in the light propagation direction and is used for controlling the dispersion compensation quantity of the grating;
after the optical signal is input through the input end straight waveguide, the optical signal is selectively connected with a next-stage polarization independent antisymmetric grating or connected with a next-stage straight waveguide through the polarization independent optical switch when passing through each polarization independent optical switch; the input optical signals with different wavelengths are reflected at different positions of the polarization-independent antisymmetric grating, so that different delay amounts are obtained, and flat dispersion is formed in a certain bandwidth; the grating waveguide structure has left-right antisymmetry and up-down asymmetry, and the input light can generate polarization rotation after being reflected by the grating, namely, the input TE polarized light is changed into TM polarization after being reflected, the input TM polarized light is changed into TE polarization, and the polarization rotation cannot be realized in the conventional grating; different dispersion amounts can be obtained by changing the gradient of the width change of the grating waveguide, and the dispersion amounts are input to a polarization independent optical switch at the subsequent stage after compensation.
2. The polarization independent integrated tunable dispersion compensation chip based on a switching cascaded antisymmetric grating of claim 1, wherein: the polarization independent optical switch can be a Mach-Zehnder interference optical switch structure and consists of two polarization independent 3dB optical splitters and an upper adjusting arm and a lower adjusting arm which are connected with the two 3dB optical splitters, wherein the upper adjusting arm and the lower adjusting arm are respectively formed by a front phase shifter, a rear phase shifter and a middle polarization rotator (for realizing the mutual conversion of TE polarization and TM polarization); and simultaneously, the front phase shifter and the rear phase shifter are adjusted to obtain polarization independent phase shifting.
3. The polarization independent integrated tunable dispersion compensation chip based on a switching cascaded antisymmetric grating of claim 1, wherein: the polarization independent optical switch can be a micro-ring resonant cavity structure, and is composed of two sections of parallel straight waveguides and one or more micro-ring resonators. The coupling area of the straight waveguide and the micro-ring resonator has polarization insensitivity, namely, the coupling area has the same coupling coefficient for TE and TM polarization, and the micro-ring resonator comprises two polarization rotators and two phase shifters which are in staggered cascade connection, so that half TE polarized light and half TM polarized light exist in the micro-ring when different polarizations are input, and the two polarization states have the same resonant wavelength. Simultaneously, the two phase shifters are adjusted, the resonance wavelength is moved, and the output optical signals can be in a direct-pass or download state, so that the signals can be switched between output ports.
4. The polarization independent integrated tunable dispersion compensation chip based on a switching cascaded antisymmetric grating of claim 1, wherein: the polarization independent optical switch and the polarization independent antisymmetric grating are formed by ridge waveguides; the chip material is silicon, silicon nitride, silicon dioxide, indium phosphide or thin film lithium niobate.
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| CN117452546A (en) * | 2023-11-14 | 2024-01-26 | 曲阜师范大学 | Double-layer grating broadband terahertz polarization wave plate based on dispersion compensation mechanism |
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| CN117452546A (en) * | 2023-11-14 | 2024-01-26 | 曲阜师范大学 | Double-layer grating broadband terahertz polarization wave plate based on dispersion compensation mechanism |
| CN117452546B (en) * | 2023-11-14 | 2024-05-03 | 曲阜师范大学 | Double-layer grating broadband terahertz polarization wave plate based on dispersion compensation mechanism |
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