Polarization control apparatus and optical system

Abstract

The present application relates to a polarization control apparatus and an optical system. The polarization control apparatus comprises a polarization phase shifter, an input polarization rotator and an output polarization rotator, wherein the polarization phase shifter comprises a polarization phase shift structure, an input conversion structure and an output conversion structure, the polarization phase shift structure comprising a first waveguide, a first electrode and a second electrode, and the polarization phase shift structure being configured to adjust, under the control of the first electrode and the second electrode, the phase of a light wave in the first waveguide on the basis of a linear electro-optic effect of the first waveguide. The polarization control apparatus can obtain a relatively short waveguide length and can avoid operating under relatively high heat conditions, and thus the integration level, reliability and durability of the polarization control apparatus can be improved.

Description

Polarization control device and optical system

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 6, 2023, with application number 202322411337.9 and invention name “Polarization Control Device and Optical System”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of integrated optics, and in particular to a polarization control device and an optical system. Background Art

[0003] Polarization control is a fundamental requirement of optical systems. Currently, most commercially available polarization control devices are free-space devices. However, the development of integrated optics requires integrated polarization control devices.

[0004] In the related art, a typical integrated polarization control device is based on silicon waveguides. For example, it can be composed of multiple silicon waveguide polarization rotators and multiple silicon waveguide polarization phase shifters connected alternately. In this way, the silicon waveguide polarization rotators can convert the polarization state of light to produce two different polarizations, while the silicon waveguide polarization phase shifters can adjust the relative phase difference between the two polarizations.

[0005] However, silicon waveguide polarization phase shifters typically rely on heaters for phase adjustment. Because the heater's effect on the refractive index changes of the two polarized light beams within the silicon waveguide is relatively similar, achieving the target phase difference often requires significant heat or a longer silicon waveguide. However, significant heat is detrimental to the long-term operation of the polarization control device, potentially affecting its reliability and durability. Meanwhile, a longer silicon waveguide can reduce the optical bandwidth of the optical system in which the polarization control device resides, hindering its optical performance. Utility Model Content

[0006] Based on this, it is necessary to provide a polarization control device and an optical system to address the above technical problems, which can obtain a shorter waveguide length and avoid working under high heat conditions, thereby helping to improve the integration, reliability and durability of the polarization control device.

[0007] On the one hand, an embodiment of the present application provides a polarization control device, which is disposed on a substrate and includes: a polarization phase shifter, an input polarization rotator, and an output polarization rotator; wherein the polarization phase shifter includes: a polarization phase shifting structure, an input conversion structure, and an output conversion structure. The polarization phase shifting structure includes a first waveguide, a first electrode, and a second electrode. The first waveguide extends along a first direction and has an input end and an output end, respectively. The first electrode and the second electrode are located on both sides of the first waveguide. The polarization phase shifting structure is configured to adjust the phase of the light wave in the first waveguide under the control of the first electrode and the second electrode based on the linear electro-optical effect of the first waveguide. The input conversion structure includes a second waveguide; the second waveguide has an input end and an output end, respectively, and the output end of the second waveguide is coupled to the input end of the first waveguide; the input conversion structure is configured to couple the light wave in the second waveguide into the first waveguide. The output conversion structure includes a third waveguide having an input end and an output end, the input end of the third waveguide being coupled to the output end of the first waveguide. The output conversion structure is configured to couple the phase-adjusted lightwave from the first waveguide to the third waveguide. An input polarization rotator has an input end and an output end, the output end of the input polarization rotator being coupled to the input end of the second waveguide. The input polarization rotator is configured to convert the input polarization lightwave into a first polarization state lightwave and a second polarization state lightwave, and transmit the first polarization state lightwave and the second polarization state lightwave to the second waveguide. An output polarization rotator has an input end and an output end, the input end of the output polarization rotator being connected to the output end of the third waveguide, and is configured to perform a polarization conversion of the first polarization state lightwave and the second polarization state lightwave in the third waveguide at a preset ratio.

[0008] In an embodiment of the present application, a polarization control device includes a polarization phase shifter, an input polarization rotator, and an output polarization rotator. The polarization phase shifter includes a polarization phase shifting structure, an input conversion structure, and an output conversion structure. The polarization phase shifter can achieve light wave transmission between the second waveguide and the first waveguide via the input conversion structure, adjust the phase of the light wave in the first waveguide based on the linear electro-optical effect of the first waveguide in the polarization phase shifting structure, and then achieve light wave transmission between the first waveguide and the third waveguide via the output conversion structure. In this manner, a first electrode and a second electrode are provided on either side of the first waveguide. By utilizing the linear electro-optical effect of the first waveguide and adjusting the voltage applied to the first and second electrodes, the electric field applied to the first waveguide can be conveniently and accurately adjusted, thereby accurately adjusting the phase of the light wave in the first waveguide. This avoids reliance on a heater for phase adjustment, effectively shortens the length of the first waveguide, and prevents the polarization phase shifter from operating under high heat conditions, thereby improving the reliability and durability of the polarization control device.

[0009] An input polarization rotator is coupled to the input end of the second waveguide. The input polarization rotator can be used to convert the input polarization light wave into a first polarization state light wave and a second polarization state light wave, which are then transmitted to the second waveguide respectively. This facilitates the subsequent polarization phase shifter to adjust the phase difference between the first polarization state light wave and the second polarization state light wave to obtain light waves with different polarization states in different proportions.

[0010] Furthermore, an output polarization rotator is provided at the output end of the third waveguide to convert the polarization states of the first polarization state lightwave and the second polarization state lightwave in the third waveguide at a preset ratio. This allows the polarization control device to output lightwaves containing different polarization states in varying ratios, as needed, to meet diverse usage requirements, thereby enhancing its versatility.

[0011] In some embodiments, the input polarization rotator includes an input waveguide, wherein the input waveguide and the second waveguide are an integral structure.

[0012] In the embodiment of the present application, the input waveguide and the second waveguide in the input polarization rotator can be an integrated structure. In this way, the input waveguide and the second waveguide can be simultaneously manufactured based on the same process, which is conducive to improving the integration of the polarization control device.

[0013] In some embodiments, the output polarization rotator includes an output waveguide, wherein the output waveguide and the third waveguide are an integrated structure.

[0014] In the embodiment of the present application, the output waveguide and the third waveguide in the output polarization rotator can be an integrated structure. In this way, the output waveguide and the third waveguide can be simultaneously manufactured based on the same process, which is conducive to improving the integration of the polarization control device.

[0015] In some embodiments, the polarization control apparatus further includes an output phase shifter. The output phase shifter has an input and an output, wherein the input of the output phase shifter is coupled to the output of the output polarization rotator. The output phase shifter is configured to adjust the phase of the light wave output by the output polarization rotator.

[0016] In an embodiment of the present application, the output phase shifter can adjust the phase of the light waves output by the output polarization rotator, such as the first polarization state light waves and the second polarization state light waves, and form an arbitrary phase difference between the two, thereby achieving arbitrary adjustment of the ratio of the first polarization state light waves and the second polarization state light waves, thereby allowing the first polarization state light waves and the second polarization state light waves to be processed into light waves including light waves of arbitrary polarization states, further broadening the range of light wave types that can be output by the polarization control device provided by the present application.

[0017] In some embodiments, the polarization control apparatus further includes an input phase shifter. The input phase shifter has an input end and an output end, and the output end of the input phase shifter is connected to the input end of the input polarization rotator. The input phase shifter is configured to adjust the phase of the input polarized lightwave and transmit the phase-adjusted input polarized lightwave to the input polarization rotator.

[0018] In the embodiments of the present application, the input phase shifter can adjust the phase of the input polarized lightwave. For example, it can process a lightwave containing any polarization state into a lightwave containing a first polarization state and a second polarization state, and transmit the obtained first polarization state and second polarization state lightwaves to the input polarization rotator. This allows for subsequent processing such as polarization rotation and phase difference adjustment on the first and second polarization state lightwaves. This further broadens the range of lightwave types that can be processed by the polarization control device provided by the present application.

[0019] In some embodiments, the material of the first waveguide includes: X-cut lithium niobate.

[0020] In some embodiments, the material of the second waveguide and / or the third waveguide includes: a silicon-based material.

[0021] In some embodiments, the material of the input waveguide and / or the output waveguide includes: a silicon-based material.

[0022] In some embodiments, the polarization control device further includes: a lower cladding layer and an upper cladding layer, wherein the lower cladding layer is located on the substrate; and the upper cladding layer covers a surface of the lower cladding layer that is away from the substrate.

[0023] In some embodiments, the polarization phase shifter, the input polarization rotator, the output polarization rotator, the output phase shifter, and the input phase shifter are all located between the lower cladding layer and the upper cladding layer.

[0024] In the above embodiments, the polarization control device includes a lower cladding layer and an upper cladding layer stacked on a substrate. The polarization phase shifter, input polarization rotator, output polarization rotator, output phase shifter, and input phase shifter are also disposed between the lower cladding layer and the upper cladding layer. As such, the polarization phase shifter provided in this application can be fabricated using a relatively mature silicon-photonics integration process. This allows the polarization phase shifter provided in this application to have good integration and compatibility with widely used silicon-based optical devices in related technologies.

[0025] On the other hand, an embodiment of the present application provides an optical system, including the polarization control device described in some of the above embodiments.

[0026] The optical system provided in the embodiments of the present application has the same technical advantages as the polarization control devices described in some of the aforementioned embodiments, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] FIG1 is a schematic structural diagram of a polarization control device provided in some embodiments;

[0029] FIG2 is a schematic diagram of the three-dimensional structure of the polarization control device shown in FIG1 ;

[0030] FIG3 is a schematic structural diagram of an input polarization rotator provided in some embodiments;

[0031] FIG4 is a schematic cross-sectional view of the structure shown in FIG5 along the AA direction and the BB direction;

[0032] FIG5 is a schematic structural diagram of another polarization control device provided in some embodiments;

[0033] FIG6 is a schematic structural diagram of another polarization control device provided in some embodiments;

[0034] FIG7 is a schematic cross-sectional view of a polarization phase shift structure provided in some embodiments;

[0035] FIG8 is a schematic cross-sectional view of the structure of FIG7 along the CC direction;

[0036] FIG9 is a schematic structural diagram of an input conversion structure provided in some embodiments;

[0037] FIG10 is a schematic diagram of an orthographic projection of the second waveguide and the coupled first waveguide on the substrate in the structure of FIG9 ;

[0038] FIG11 is a schematic structural diagram of an output conversion structure provided in some embodiments;

[0039] FIG12 is a schematic diagram of an orthographic projection of the third waveguide and the coupled first waveguide on a substrate in the structure shown in FIG11 .

[0040] Description of reference numerals:

[0041] 1-polarization control device, 11-polarization phase shifter, 111-polarization phase shift structure, 112-input conversion structure, 113-output conversion structure, 1111-first waveguide, 1112-first electrode, 1113-second electrode, 1121-second waveguide, 1131-third waveguide, 1141-fourth waveguide, 1151-fifth waveguide, 12-input polarization rotator, 121-input waveguide, 13-output polarization rotator, 131-output waveguide, 14-output phase shifter, 141-output phase shift structure, 142-third conversion structure, 143-fourth conversion structure, 15-input phase shifter, 151-input phase shift structure, 152-first conversion structure, 153-second conversion structure, 16-substrate; 17-lower cladding, 18-upper cladding, 19-connecting pad, H1-electrode lead-out hole, A1-input area, A2-polarization rotation area, A3-output area. DETAILED DESCRIPTION

[0042] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0044] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intervening element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc., if there is transmission of electrical signals or data between the connected objects.

[0045] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0046] One embodiment of the present application provides a polarization control device, as shown in Figures 1 and 2. The polarization control device 1 is disposed on a substrate 16 and includes a polarization phase shifter 11, an input polarization rotator 12, and an output polarization rotator 13. The polarization phase shifter 11 includes a polarization phase shifting structure 111, an input conversion structure 112, and an output conversion structure 113. The polarization phase shifting structure 111 includes a first waveguide 1111, a first electrode 1112, and a second electrode 1113. The first waveguide 1111 extends along a first direction (e.g., the X direction). The first and second electrodes 1112 and 1113 are located on either side of the first waveguide 1111. The polarization phase shifting structure 111 is configured to adjust the phase of a light wave in the first waveguide 1111 under the control of the first and second electrodes 1112 and 1113 based on the linear electro-optical effect of the first waveguide 1111. The input conversion structure 112 includes a second waveguide 1121 and a fourth waveguide 1141 optically connected to the second waveguide 1121. The fourth waveguide 1141 and the first waveguide 1111 are connected to a single waveguide, that is, the fourth waveguide 1141 and the first waveguide 1111 are different parts of the same waveguide. The input conversion structure 112 is configured to couple the lightwave from the second waveguide 1121 into the first waveguide 1111. The output conversion structure 113 includes a third waveguide 1131 and a fifth waveguide 1151 optically coupled to the third waveguide 1131. The fifth waveguide 1151 and the first waveguide 1111 are connected to a single waveguide, that is, the fourth waveguide 1141, the fifth waveguide 1151 and the first waveguide 1111 are different parts of the same waveguide. The output conversion structure 113 is configured to couple the phase-adjusted lightwave from the first waveguide 1111 out into the third waveguide 1131. The input polarization rotator 12 is optically connected to the second waveguide 1121 and is configured to convert the input polarized lightwave into a first polarization state lightwave and a second polarization state lightwave, and transmit the first polarization state lightwave and the second polarization state lightwave to the second waveguide 1121. The output polarization rotator 13 is optically connected to the third waveguide 1131 and is configured to perform a polarization conversion of the first polarization state lightwave and the second polarization state lightwave in the third waveguide 1131 at a preset ratio.

[0047] Here, the linear electro-optic effect of a waveguide refers to its ability to linearly change its refractive index in response to changes in an externally applied electric field. This change in the waveguide's refractive index also alters the phase of light waves entering the waveguide, such as transverse electric (TE) or transverse magnetic (TM) waves.

[0048] In the embodiment of the present application, the polarization phase shifter 11 can achieve light wave transmission between the second waveguide 1121 and the first waveguide 1111 through the input conversion structure 112, adjust the phase of the light wave in the first waveguide 1111 based on the linear electro-optical effect of the first waveguide 1111 in the polarization phase shifting structure 111, and then achieve light wave transmission between the first waveguide 1111 and the third waveguide 1131 through the output conversion structure 113. In this way, the first electrode 1112 and the second electrode 1113 are respectively provided on both sides of the first waveguide 1111. The linear electro-optical effect of the first waveguide 1111 can be utilized to conveniently and accurately adjust the electric field applied to the first waveguide 1111 by adjusting the voltage applied to the first electrode 1112 and the second electrode 1113, so that the phase of the light wave in the first waveguide 1111 can be accurately adjusted to avoid relying on a heater for phase adjustment, thereby effectively shortening the length of the first waveguide 1111 and avoiding the polarization phase shifter 11 from operating under high heat conditions, thereby improving the reliability and durability of the polarization control device 1.

[0049] The input end of the second waveguide 1121 is coupled to the input polarization rotator 12, which can be used to convert the input polarized lightwave into a first polarization state lightwave and a second polarization state lightwave. The first polarization state lightwave and the second polarization state lightwave are, for example, TE waves and TM waves. The first polarization state lightwave and the second polarization state lightwave are then transmitted to the second waveguide 1121, thereby facilitating the subsequent polarization phase shifter 11 to adjust the phase difference between the first polarization state lightwave and the second polarization state lightwave, thereby obtaining lightwaves containing different proportions of the first polarization state and the second polarization state.

[0050] Furthermore, an output polarization rotator 13 is provided at the output end of the third waveguide 1131. This output polarization rotator 13 can be used to convert the polarization states of the first polarization state lightwave and the second polarization state lightwave in the third waveguide 1131 at a preset ratio. In this way, the polarization control device 1 can output lightwaves of different polarization states in different ratios, as needed, to meet various usage requirements, thereby enhancing the versatility of the polarization control device 1.

[0051] In some examples, the material of the first waveguide 1111 includes X-cut lithium niobate. The material of the second waveguide 1121 and the third waveguide 1131 can be silicon or silicon nitride.

[0052] Optionally, the linear electro-optic coefficient of the first waveguide 1111 includes: n TE0 3 r 33 -n TM0 3 r 13 , r 33 = 30pm / v, r 13= 7.5pm / v; where n TE0 Represents the refractive index of the waveguide for TE mode light waves; n TM0 represents the refractive index of the waveguide for TM mode light waves; r 33 represents the component of the electro-optic coefficient of the lithium niobate thin film crystal on the (3,3) element of the electro-optic coefficient matrix; r 13 Represents the component of the electro-optic coefficient of lithium niobate thin film crystal on the (1,3) element of the electro-optic coefficient matrix.

[0053] Based on this, the polarization control device 1 provided in the embodiment of the present application can utilize the linear electro-optic effect of the first waveguide 1111 to linearly change the refractive index of the first waveguide 1111 by changing the voltage applied to the first electrode 1112 and the second electrode 1113, thereby linearly changing the phase of the light wave in the first waveguide 1111. In other words, there is a linear relationship between the externally applied voltage and the refractive index of the first waveguide 1111. This allows the phase of the light wave entering the first waveguide 1111 to be linearly adjusted, greatly improving the accuracy and convenience of phase adjustment.

[0054] Furthermore, the first waveguide 1111 has significantly different linear electro-optic coefficients for light of different polarization states, such as TE waves and TM waves. Thus, the polarization control device 1 can generate a predetermined phase difference between the TE and TM waves entering the first waveguide 1111 by applying a small voltage to the first waveguide 1111, thereby eliminating the need for a longer waveguide length.

[0055] In some examples, substrate 16 may be a silicon substrate, a silicon oxide substrate, or a silicon nitride substrate.

[0056] In some embodiments, the first electrode 1112 and the second electrode 1113 may each include a strip-shaped electrode.

[0057] In some examples, the ends of the second waveguide 1121 and the first waveguide 1111 can be coupled together by adiabatic coupling perpendicular to the thickness direction of the substrate 16. In this way, the light wave input through the second waveguide 1121 can be coupled into the first waveguide 1111 with low loss through the input conversion structure 112, thereby facilitating the polarization phase shifting structure 111 to adjust the phase of the input light wave.

[0058] In some embodiments, the material of the second waveguide 1121 and / or the third waveguide 1131 includes: a silicon-based material.

[0059] Similarly, the third waveguide 1131 is adiabatically coupled to the ends of the first waveguide 1111. Thus, the lightwave processed by the polarization phase shifting structure 111 can be coupled into the third waveguide 1131 with low loss through the output conversion structure 113. This lightwave can then be transmitted to other waveguides / devices.

[0060] Continuing with Figures 1 and 2 , in some embodiments, the polarization control device 1 further includes an input polarization rotator 12. The input polarization rotator 12 includes an input end and an output end, with the output end of the input polarization rotator 12 being coupled to the second waveguide 1121. The input polarization rotator 12 is configured to convert an input polarized lightwave into a first polarization state lightwave and a second polarization state lightwave, and transmit the first polarization state lightwave and the second polarization state lightwave to the second waveguide 1121. This facilitates the subsequent polarization phase shifter 11 to adjust the phase difference between the first polarization state lightwave and the second polarization state lightwave, thereby obtaining lightwaves of different polarization states containing different proportions.

[0061] In some embodiments, the input polarization rotator 12 can rotate the polarization angle of the input polarized light wave, such as the TE wave or the TM wave, so that the mode of a portion of the input polarized light wave is converted, thereby converting the TM wave or the TE wave into a desired ratio of TM wave and TE wave.

[0062] 2 , in some embodiments, the input polarization rotator 12 includes an input waveguide 121. The input waveguide 121 and the second waveguide 1121 are integrally formed. In other words, the input waveguide 121 and the second waveguide 1121 can be fabricated simultaneously using the same process, simplifying the manufacturing process.

[0063] In some embodiments, the material of the input waveguide and / or the output waveguide includes: a silicon-based material.

[0064] Referring to Figures 3 and 4 , in some possible implementations, the input waveguide 121 in the input polarization rotator 12 can be divided into an input region A1, a polarization rotation region A2, and an output region A3, which are sequentially connected. The input region A1 and the output region A3 of the input waveguide 121 have rectangular cross-sectional shapes along the second direction (e.g., the Y direction, perpendicular to the first direction); the polarization rotation region A2 has an L-shaped cross-sectional shape along the second direction (e.g., the Y direction). In this way, when an input polarized light wave, such as a TE wave, enters and is transmitted from the input area A1 to the polarization rotation area A2, the cross-sectional shape of the input waveguide 121 suddenly changes from a symmetrical rectangle to an asymmetrical L-shape, causing a portion of the TE wave to undergo mode hybridization and be converted into a TM wave, so that a certain proportion of TE waves and TM waves can be output from the output area A3. Alternatively, when an input TM wave enters and is transmitted from the input area A1 to the polarization rotation area A2, the cross-sectional shape of the input waveguide 121 suddenly changes from a symmetrical rectangle to an asymmetrical L-shape, causing a portion of the TM wave to undergo mode hybridization and be converted into a TE wave, so that a certain proportion of TE waves and TM waves can be output from the output area A3.

[0065] Continuing with Figures 1 and 2 , in some embodiments, the polarization control device 1 further includes an output polarization rotator 13. The output polarization rotator 13 has an input end and an output end, with the input end of the output polarization rotator 13 connected to the output end of the third waveguide 1131. The output polarization rotator 13 is configured to convert the polarization states of the first polarization state lightwave and the second polarization state lightwave in the third waveguide 1131 by a predetermined ratio.

[0066] In this embodiment of the present application, an output polarization rotator 13 is provided at the output end of the third waveguide 1131. This output polarization rotator 13 can be used to convert the polarization states of the first polarization state lightwave and the second polarization state lightwave in the third waveguide 1131 by a predetermined ratio. Thus, the first polarization state lightwave and the second polarization state lightwave (e.g., TE wave and TM wave) output by the polarization phase shifter 11, which include any ratio, are transmitted to the output polarization rotator 13. The output polarization rotator 13 can further convert the polarization states of the two polarization state lightwaves by a predetermined ratio and output corresponding polarization state lightwaves in different ratios to meet various usage requirements, thereby enhancing the versatility of the polarization control device 1.

[0067] Continuing with FIG2 , in some embodiments, the output polarization rotator 13 includes an output waveguide 131. The output waveguide 131 and the third waveguide 1131 are integrally formed. Thus, the output waveguide 131 and the third waveguide 1131 can be fabricated simultaneously using the same process, thereby improving the integration of the polarization control device 1.

[0068] As can be understood from Figures 2 to 4 , in some possible embodiments, the output waveguide 131 in the output polarization rotator 13 can have the same structure as the input waveguide 121. Specifically, the output waveguide 131 can be divided into a sequentially connected input region A1, a polarization rotation region A2, and an output region A3. The input region A1 and the output region A3 have rectangular cross-sections in the Y direction, while the polarization rotation region A2 has an L-shaped cross-section in the Y direction. In this way, the output polarization rotator 13 can further process the TE and TM waves obtained from the polarization phase shifter 11, which contain a certain ratio, into TE and TM waves containing a predetermined ratio.

[0069] In some of the following embodiments, the range of light wave types that can be output by the polarization control device 1 and the range of light wave types that can be accepted by the polarization control device 1 are further broadened by further optimizing the settings of related components.

[0070] Referring to FIG5 , in some embodiments, the polarization control device 1 includes, in addition to the structure shown in FIG1 , an output phase shifter 14. The output phase shifter 14 has an input end and an output end, and the input end of the output phase shifter 14 is coupled to the output end of the output polarization rotator 13. The output phase shifter 14 is configured to adjust the phase of the lightwave output by the output polarization rotator 13.

[0071] Continuing with FIG. 5 , in some embodiments, the output phase shifter 14 includes an output phase shift structure 141, a third conversion structure 142 coupled to the input end of the output phase shift structure 141, and a fourth conversion structure 143 coupled to the output end of the output phase shift structure 141. The output phase shift structure 141 has the same structure as the polarization phase shift structure 111. The third conversion structure 142 has the same structure as the input conversion structure 112. The fourth conversion structure 143 has the same structure as the output conversion structure 113. Furthermore, the second waveguide 1121 in the third conversion structure 142 is of the same type as the output waveguide 131 in the output polarization rotator 13, or they can be connected to form an integrated structure. The output phase shift structure 141 and the polarization phase shift structure 111 can be positioned adjacent to each other in the polarization control device 1. This allows hybrid integration by integrating different types of lithium niobate substrates within a silicon substrate, thereby simultaneously achieving the effect of creating several lithium niobate waveguides. In other words, by placing the output phase-shift structure 141 and the polarization phase-shift structure 111 adjacent to each other on the integrated chip, they can share a single lithium niobate substrate. Thus, a single lithium niobate substrate can be used to form two phase-shift structures. This reduces process steps, and component layout can be achieved by connecting a curved waveguide between the output phase-shift structure 141 and the polarization phase-shift structure 111.

[0072] In an embodiment of the present application, the output phase shifter 14 can adjust the light wave output by the output polarization rotator 13, such as the phase of the first polarization state light wave and the second polarization state light wave, and form an arbitrary phase difference between the two, so that the ratio of the first polarization state light wave and the second polarization state light wave can be arbitrarily adjusted, and then light waves including any polarization state can be obtained, further broadening the range of light wave types that can be output by the polarization control device 1 provided in the present application.

[0073] Continuing with FIG5 , it should be noted that in some embodiments of the present application, the various components provided are connected via waveguides (e.g., a first waveguide, a second waveguide, or a third waveguide). The arrangement of the waveguides is not limited to extending in a single direction; they can also be arranged in a curved manner to match the arrangement space of the polarization control device 1.

[0074] Referring to FIG. 6 , in some embodiments, the polarization control device 1 includes, in addition to the structure shown in FIG. 5 , an input phase shifter 15. The input phase shifter 15 has an input end and an output end, with the output end of the input phase shifter 15 connected to the input end of the input polarization rotator 12. The input phase shifter 15 is configured to adjust the phase of an input polarized lightwave and transmit the phase-adjusted input polarized lightwave to the input polarization rotator 12.

[0075] Continuing with FIG6 , in some embodiments, the input phase shifter 15 includes an input phase shift structure 151, a first conversion structure 152 coupled to the input end of the input phase shift structure 151, and a second conversion structure 153 coupled to the output end of the input phase shift structure 151. The input phase shift structure 151 has the same structure as the polarization phase shift structure 111. The first conversion structure 152 has the same structure as the input conversion structure 112. The second conversion structure 153 has the same structure as the output conversion structure 113. Furthermore, the third waveguide 1131 in the second conversion structure 153 is of the same type as the input waveguide 121 in the input polarization rotator 12, or they may be connected to form an integrated structure.

[0076] In the embodiment of the present application, the input phase shifter 15 can adjust the phase of the input polarized light wave. For example, it can process a light wave containing any polarization state into a light wave containing a first polarization state and a second polarization state, and transmit the obtained first polarization state and second polarization state light waves to the input polarization rotator 12. This facilitates subsequent processing such as polarization rotation and phase difference adjustment on the first polarization state and second polarization state light waves. This further broadens the range of light wave types that can be processed by the polarization control device 1 provided by the present application.

[0077] 2 , in some embodiments, the polarization control device 1 further includes a lower cladding layer 17 and an upper cladding layer 18 . The lower cladding layer 17 is located on the substrate 16 , and the upper cladding layer 18 covers the surface of the lower cladding layer 17 facing away from the substrate 16 .

[0078] [Corrected 13.06.2024 according to Rule 91] It should be noted that in order to more clearly show the other film layers / devices located below the upper cladding layer 18, the upper cladding layer 18 is made transparent in some drawings (such as Figures 2, 4, 9, 11 and 12).

[0079] In some examples, the lower cladding layer 17 and the upper cladding layer 18 may comprise a material with a relatively low refractive index, thereby ensuring that both the lower cladding layer 17 and the upper cladding layer 18 have a significant difference in refractive index from other optical devices (e.g., the polarization phase shifter 11) disposed between the upper cladding layer 18 and the lower cladding layer 17. In this way, light waves can be confined to propagate within the optical device, thereby avoiding undesirable defects such as light wave leakage or transmission loss.

[0080] In some examples, the lower cladding layer 17 and the upper cladding layer 18 may include a silicon oxide layer or a polysilicon layer.

[0081] In some embodiments, the polarization phase shifter 11 , the input polarization rotator 12 , the output polarization rotator 13 , the output phase shifter 14 , the input phase shifter 15 and the waveguides in each device may be correspondingly arranged between the lower cladding 17 and the upper cladding 18 .

[0082] In some examples, the input waveguide 121 in the input polarization rotator 12 has a different material than both the lower cladding 17 and the upper cladding 18. Alternatively, the input waveguide 121 may include a silicon material.

[0083] In some examples, the output waveguide 131 in the output polarization rotator 13 has a different material than both the lower cladding 17 and the upper cladding 18. Alternatively, the output waveguide 131 may include a silicon material.

[0084] In the above embodiment, the polarization phase shifter 11, the input polarization rotator 12, the output polarization rotator 13, the input phase shifter 14, and the output phase shifter 15 are all located between the lower cladding 17 and the upper cladding 18. In this way, the polarization control device 1 provided in this application can be manufactured using a relatively mature silicon photonics integration process. This allows the polarization control device 1 provided in this application to have better integration and achieve good compatibility with silicon-based optical devices widely used in related technologies. This further broadens the scope of application of the polarization control device 1.

[0085] Referring to Figures 7 and 8 , in some embodiments, the upper cladding layer 18 has an electrode extraction hole H1 to expose the first electrode 1112 and the second electrode 1113, respectively. The polarization control device 1 further includes a connection pad 19 disposed within the electrode extraction hole H1. The connection pad 19 is electrically connected to the first electrode 1112 and the second electrode 1113, respectively. This facilitates an external control circuit (not shown) to apply control voltages to the first electrode 1112 and the second electrode 1113, respectively, via the connection pad 19, thereby changing the electric field characteristics in the first waveguide 1111 and thereby adjusting the refractive index of the first waveguide 1111.

[0086] 9 to 12 , in some embodiments, the waveguides in each conversion structure are stacked with the coupled waveguides of different types, and their orthographic projections along the thickness direction of the substrate 16 at least partially overlap. The following description will be made using the input conversion structure 112 and the output conversion structure 113 as examples.

[0087] Referring to Figures 9 and 10 , in some embodiments, the second waveguide 1121 in the input conversion structure 112 is stacked with the coupled first waveguide 1111, and the orthographic projections of the second waveguide 1121 and the first waveguide 1111 on the substrate 16 at least partially overlap. This allows the lightwaves in the second waveguide 1121 to be gradually released into the coupled first waveguide 1111, effectively preventing mode mutations during the coupling process. This reduces transmission loss of the lightwaves in the input conversion structure 112 and improves coupling efficiency.

[0088] Referring to Figures 11 and 12 , in some embodiments, the third waveguide 1131 in the output conversion structure 113 is stacked with the coupled first waveguide 1111, and the orthographic projections of the third waveguide 1131 and the first waveguide 1111 on the substrate 16 at least partially overlap. This allows the light waves in the first waveguide 1111 to be gradually released into the coupled third waveguide 1131, effectively preventing mode mutations during the coupling process. This reduces transmission loss of the light waves in the output conversion structure 113 and improves coupling efficiency.

[0089] In some embodiments, an optical system is further provided, comprising the polarization control device 1 described in the above embodiments.

[0090] In some possible implementations, the optical system may be an optical switch. The optical switch including the polarization control device 1 may be disposed in a node area of ​​an optical communication network to implement functions such as optical signal exchange and optical signal interconnection of light waves in the optical communication network.

[0091] In some possible implementations, the optical system may be an optical modem. The optical modem including the polarization control device 1 may be disposed in an optical communication line or in an optical communication terminal device to implement functions such as optical communication transmission, optical signal processing, and optical signal access.

[0092] The optical system provided in the embodiment of the present application has the same technical advantages as the aforementioned polarization control device 1 and will not be described in detail here.

[0093] Throughout this specification, references to terms such as "some embodiments," "other embodiments," and "desired embodiments" indicate that a particular feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative descriptions of these terms do not necessarily refer to the same embodiment or example.

[0094] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A polarization control device, characterized in that: Arranged on the substrate, the polarization control device comprises: Polarization phase shifter; wherein the polarization phase shifter comprises: A polarization phase shift structure, comprising a first waveguide, a first electrode and a second electrode; the first waveguide extends along a first direction and is respectively provided with an input end and an output end; the first electrode and the second electrode are located on both sides of the first waveguide; the polarization phase shift structure is configured to: adjust the phase of the light wave in the first waveguide under the control of the first electrode and the second electrode based on the linear electro-optical effect of the first waveguide; An input conversion structure comprises a second waveguide; the second waveguide is provided with an input end and an output end, the output end of the second waveguide is coupled to the input end of the first waveguide; the input conversion structure is configured to: couple the light wave in the second waveguide into the first waveguide; An output conversion structure comprises a third waveguide; the third waveguide is provided with an input end and an output end, and the input end of the third waveguide is coupled to the output end of the first waveguide; the output conversion structure is configured to: couple the light wave after the phase is adjusted in the first waveguide out to the third waveguide; An input polarization rotator; the input polarization rotator is provided with an input end and an output end, and the output end of the input polarization rotator is coupled to the input end of the second waveguide; the input polarization rotator is configured to: convert the input polarized light wave into a first polarization state light wave and a second polarization state light wave, and transmit the first polarization state light wave and the second polarization state light wave to the second waveguide; An output polarization rotator; the output polarization rotator is provided with an input end and an output end, the input end of the output polarization rotator is connected to the output end of the third waveguide, and is configured to: perform a polarization state conversion of the first polarization state light wave and the second polarization state light wave in the third waveguide in a preset proportion.

2. The polarization control device according to claim 1, characterized in that: The input polarization rotator comprises an input waveguide; wherein the input waveguide and the second waveguide are an integral structure.

3. The polarization control device according to claim 1, characterized in that: The output polarization rotator comprises an output waveguide; wherein the output waveguide and the third waveguide are an integral structure.

4. The polarization control device according to claim 2 or 3, characterized in that: Also includes: An output phase shifter is provided with an input end and an output end, wherein the input end of the output phase shifter is coupled to the output end of the output polarization rotator; the output phase shifter is configured to adjust the phase of the light wave output by the output polarization rotator.

5. The polarization control device according to claim 4, characterized in that: Also includes: An input phase shifter, wherein the input phase shifter is provided with an input end and an output end, and the output end of the input phase shifter is connected to the input end of the input polarization rotator; The input phase shifter is configured to adjust the phase of the input polarized light wave and transmit the input polarized light wave after the phase adjustment to the input polarization rotator.

6. The polarization control device according to claim 1, characterized in that: The material of the first waveguide includes: X-cut lithium niobate.

7. The polarization control device according to claim 4, characterized in that: The second waveguide and / or the third waveguide are made of silicon or silicon nitride.

8. [Corrected 13.06.2024 according to Rule 91] The polarization control device according to claim 7, characterized in that The input polarization rotator comprises an input waveguide; the output polarization rotator comprises an output waveguide; wherein the input waveguide and the second waveguide are an integral structure; the output waveguide and the third waveguide are an integral structure; The input waveguide and / or the output waveguide are made of silicon or silicon nitride.

9. [Corrected 13.06.2024 according to Rule 91] The polarization control device according to claim 8, characterized in that Also includes: A lower cladding layer, located on the substrate; An upper cladding layer, covering a surface of the lower cladding layer facing away from the substrate; The polarization phase shifter, the input polarization rotator, the output polarization rotator, the output phase shifter and the input phase shifter are all located between the lower cladding layer and the upper cladding layer.

10. An optical system, characterized in that: It comprises a polarization control device as described in any one of claims 1 to 9.

Images