Optical polarizer and optical fiber gyroscope
By designing the mode hybrid zone and the mode coupling zone in the optical polarizer, and converting the TM0 mode to the TE0 mode, the problems of optical power loss and signal crosstalk in the prior art are solved, and efficient light bias and utilization improvement are achieved.
Patent Information
- Application Number
- CN202311757920.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-19
- Publication Date
- 2025-06-20
AI Technical Summary
Existing optical polarizers result in nearly half of the optical power loss when removing the TM mode, reducing the light utilization rate, and generating stray TM light leads to signal crosstalk.
An optical polarizer is designed, including a mode hybrid area, a mode coupling area and a photosynthetic beam area. The TM0 mode is converted to TE1 mode through the mode hybrid area, and the TE1 mode is converted to TE0 mode in the mode coupling area, so as to achieve multiplexing of the original TM0 mode in the input light.
While achieving the purpose of bias, the optical power loss is reduced, the light utilization rate is improved, and signal crosstalk is reduced.
Smart Images
Figure CN120178414A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of optical devices, and particularly to an optical polarizer and a fiber optic gyroscope. Background Art
[0002] When light propagates in an integrated optical waveguide, it has two polarization states, namely the transverse electric mode (abbreviated as TE mode) and the transverse magnetic mode (abbreviated as TM mode), which are the inherent properties of light. High-precision applications such as fiber optic gyroscopes that use low-bias light sources are very sensitive to the polarization state. Such applications hope that the light transmission process can contain only one polarization state as much as possible. Therefore, a polarizer is used on the optical path to remove one polarization state from the input light and retain only the other polarization state (for example, removing TM and retaining TE).
[0003] The existing polarization schemes mainly achieve the polarization effect through mode filtering or separation, including: the polarization scheme based on the optical loss of a bent waveguide, the polarization separation scheme, etc. For example, a polarization scheme based on the optical loss of a bent waveguide disclosed in the prior art mainly designs a waveguide with a specific refractive index into a bent waveguide structure, and utilizes the principle that the losses of the TM mode and the TE mode in the bent waveguide structure are different (where the TE mode can maintain low-loss transmission while the TM mode is greatly attenuated). Thus, the original TM mode in the input light is removed and the TE mode is retained to achieve the polarization purpose. Another example is a polarization separation scheme disclosed in the prior art, which mainly separates the TM mode and the TE mode in the input light into two output paths by using a separation device (such as a Y-branch structure, etc.), and then uses a metal to absorb one of the separated modes and retain the other required mode.
[0004] However, the defects of the above prior art are as follows: on the one hand, since the original TM light in the input light is removed, this will cause the optical power loss to be nearly half, and the utilization rate of light is greatly reduced, thereby limiting the device performance; on the other hand, the stray TM light generated during the removal process of the TM light will also cause problems such as signal crosstalk and system performance degradation. Summary of the Invention
[0005] The technical problem solved by the embodiments of the present invention is how to achieve the effect of reducing the optical power loss while achieving the polarization purpose.
[0006] To solve the above technical problems, an embodiment of the present invention provides an optical polarizer, which includes: a mode hybridization region, a mode coupling region, and a photosynthetic beam region; the input end of the mode coupling region is coupled to the output end of the mode hybridization region, and the first output end and the second output end of the mode coupling region are respectively coupled to the first input end and the second input end of the photosynthetic beam region; wherein, the mode hybridization region is configured to receive input light including TE0 mode and TM0 mode, convert the TM0 mode into TE1 mode, and then input the TE1 mode and the original TE0 mode in the input light into the mode coupling region; the mode coupling region is configured to output the original TE0 mode received from the first output end of the mode coupling region, and convert the received TE1 mode into TE0 mode, and then output the converted TE0 mode from the second output end of the mode coupling region; the photosynthetic beam region is configured to receive the two beams of TE0 mode output from the first output end and the second output end of the mode coupling region and perform beam combining processing.
[0007] Optionally, the mode hybridization region is formed with a tapered waveguide, the first end of the tapered waveguide is configured to receive input light including TE0 mode and TM0 mode, and the second end of the tapered waveguide is coupled to the input end of the mode coupling region; the tapered waveguide gradually widens from the first end to the second end to convert the TM0 mode in the input light into TE1 mode, and then input the TE1 mode and the original TE0 mode in the input light into the mode coupling region.
[0008] Optionally, the refractive index of the upper cladding of the tapered waveguide is greater than that of the lower cladding.
[0009] Optionally, the width difference between the width of the second end and the width of the first end of the tapered waveguide is greater than or equal to a first preset threshold; the length of the tapered waveguide is greater than or equal to a second preset threshold; wherein, the greater the width difference, the greater the second preset threshold.
[0010] Optionally, the mode coupling region is formed with a first double-waveguide structure, the first double-waveguide structure includes a first waveguide and a second waveguide; the first end of the first waveguide is coupled to the second end of the tapered waveguide, and the second end of the first waveguide is coupled to the first input end of the photosynthetic beam region, wherein, the first end of the first waveguide is configured to receive the original TE0 mode output from the second end of the tapered waveguide and then output it from the second end of the first waveguide; the first end of the second waveguide is misaligned and coupled to the second end of the tapered waveguide, and the second end of the second waveguide is coupled to the second input end of the photosynthetic beam region, wherein, the first end of the second waveguide forms a coupled light of TE0 mode based on the TE1 mode output from the second end of the tapered waveguide and then outputs it from the second end of the second waveguide.
[0011] Optionally, the first ends of the first waveguide and the second waveguide satisfy the following condition:
[0012] Neff1_TE1×R1=Neff2_TE0×R2;
[0013] wherein, Neff1_TE1 represents the effective refractive index of the TE1 mode at the first end of the first waveguide, R1 represents the bending radius of the first end of the first waveguide, Neff2_TE0 represents the effective refractive index of the TE0 mode at the first end of the second waveguide, and R2 represents the bending radius of the first end of the second waveguide.
[0014] Optionally, the distance between the first ends of the first waveguide and the second waveguide is less than the distance between the second ends of the first waveguide and the second waveguide.
[0015] Optionally, the optical polarizer further includes a phase compensation region; the first input end of the phase compensation region is coupled to the second end of the first waveguide, and the second input end of the phase compensation region is coupled to the second end of the second waveguide; the first output end of the phase compensation region is coupled to the first input end of the optical beam combining region, and the second output end of the phase compensation region is coupled to the second input end of the optical beam combining region; wherein, the phase compensation region is used to perform phase compensation on the TE0 mode output from the second end of the second waveguide, so that the phase-compensated TE0 mode is in phase with the TE0 mode output from the second end of the first waveguide, and then the two in-phase TE0 modes are input into the optical beam combining region.
[0016] Optionally, the optical polarizer further includes a second dual-waveguide structure, and the second dual-waveguide structure includes a third waveguide and a fourth waveguide; the first end of the third waveguide is coupled to the second end of the first waveguide, and the second end of the third waveguide is coupled to the first input end of the phase compensation region; the first end of the fourth waveguide is coupled to the second end of the second waveguide, and the second end of the fourth waveguide is coupled to the second input end of the phase compensation region; the width of the second end of the third waveguide is the same as the width of the second end of the fourth waveguide.
[0017] An embodiment of the present invention further provides an optical fiber gyroscope, including the above optical polarizer.
[0018] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:
[0019] An embodiment of the present invention provides an optical polarizer, which includes a mode hybridization region, a mode coupling region, and a light combining region. The input end of the mode coupling region is coupled to the output end of the mode hybridization region. The first output end and the second output end of the mode coupling region are respectively coupled to the first input end and the second input end of the light combining region. Wherein, the mode hybridization region is configured to receive input light including TE0 mode and TM0 mode, convert the TM0 mode into TE1 mode, and then input the TE1 mode and the original TE0 mode in the input light into the mode coupling region. The mode coupling region is configured to output the original TE0 mode received from the first output end of the mode coupling region, and convert the received TE1 mode into TE0 mode, and then output the converted TE0 mode (referred to as "converted TE0 mode") from the second output end of the mode coupling region. The light combining region is configured to receive the two TE0 modes output from the first output end and the second output end of the mode coupling region and perform a light combining process.
[0020] As described above, compared with the existing polarization schemes that usually directly filter out the original TM0 mode light in the input light or filter it out after separating it from the TE0 mode, in this embodiment, the original TM0 mode in the input light is converted into TE0 mode after the action of the mode hybridization region and the mode coupling region. Then, the converted TE0 mode and the original TE0 mode in the input light are combined to obtain the final TE0 mode. Thus, the reuse of the original TM0 mode in the input light can be achieved, and the effect of reducing the optical power loss can be achieved while achieving the polarization purpose.
[0021] Furthermore, since additional phases may be introduced during the processes of the mode hybridization region hybridizing the original TE0 mode in the input light to obtain TE1 mode and the mode coupling region converting the TE1 mode received from the mode hybridization region into TE0 mode, in the embodiment of the present invention, a phase compensation region is provided between the mode coupling region and the light combining region to perform phase compensation on the "converted TE0 mode". Thus, the phases of the two TE0 modes (the "converted TE0 mode" and the "original TE0 mode") finally input into the light combining region can be made consistent, making the light combining effect better, maximizing the reduction of optical power loss, and improving the utilization rate of the input light.
[0022] Further, in practical applications, the width of the first end of the first waveguide may be greater than the width of the first end of the second waveguide. Therefore, in the embodiments of the present invention, by setting the second double-waveguide structure, the width of the waveguide output end for outputting the "original TE0 mode" (i.e., the width of the second end of the third waveguide) is ensured to be the same as the width of the waveguide output end for outputting the "converted TE0 mode" (i.e., the width of the second end of the fourth waveguide). Thus, better effects of subsequent phase compensation and beam combining processing for the "converted TE0 mode" and the "original TE0 mode" can be achieved, further effectively reducing the optical power loss and realizing the full utilization of the input light. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 is a schematic structural diagram of an optical polarizer in an embodiment of the present invention;
[0024] Figure 2 is Figure 1 a specific structural diagram of the mode coupling region 11 of the shown optical polarizer;
[0025] Figure 3 is Figure 1 a coupling structural diagram of the mode hybridization region 10 and the mode coupling region 11 of the shown optical polarizer. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0026] To make the above objects, features, and beneficial effects of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings. It should be noted that the top views of the relevant device structures are shown in the drawings of the present application.
[0027] Referring to Figure 1 , Figure 1 is a schematic structural diagram of an optical polarizer in an embodiment of the present invention.
[0028] The optical polarizer may include: a mode hybridization region 10, a mode coupling region 11, and a photo beam combining region 12; the input end of the mode coupling region 11 is coupled to the output end of the mode hybridization region 10, and the first output end a1 and the second output end a2 of the mode coupling region 11 are respectively coupled to the first input end b1 and the second input end b2 of the photo beam combining region 12.
[0029] Among them, the mode hybridization region 10 is used to receive the input light containing the TE0 mode (which can be referred to as the "original TE0 mode" in this application) and the TM0 mode (which can be referred to as the "original TM0 mode" in this application), convert the TM0 mode into the TE1 mode, and then input the TE1 mode and the original TE0 mode in the input light into the mode coupling region 11.
[0030] The mode coupling region 11 is configured to output the received original TE0 mode from the first output end a1 of the mode coupling region, and to convert the received TE1 mode into the TE0 mode, and then output the converted TE0 mode (hereinafter referred to as "converted TE0 mode") from the second output end a2 of the mode coupling region 11.
[0031] The optical beam combining region 12 is configured to receive the two beams of TE0 mode output from the first output end a1 and the second output end a2 of the mode coupling region 11 and perform beam combining processing.
[0032] Specifically, the first output end a1 of the mode coupling region 11 outputs the "original TE0 mode" and inputs it into the optical beam combining region 12 from the first input end b1 of the optical beam combining region 12; the second output end a2 of the mode coupling region 11 outputs the "converted TE0 mode" and inputs it into the optical beam combining region 12 from the second input end b2 of the optical beam combining region 12 (it should be noted that in the device structures shown in the drawings of the present application, the straight arrows above and below the waveguides of each functional region represent the transmission direction of the input light in the waveguide).
[0033] In a specific implementation, the optical beam combining region 12 can adopt Figure 1 the structure shown (wherein, the two thin waveguides on the left side of the optical beam combining region 12 are input waveguides, the middle rectangle is a waveguide with a larger width, and the thin waveguide on the right side is an output waveguide), or it can also be implemented by other devices capable of realizing the functions of splitting and combining light, which are not limited in the embodiments of the present invention.
[0034] Furthermore, the mode hybridization region 10 is formed with a tapered waveguide. The first end c1 of the tapered waveguide is configured to receive the input light containing the TE0 mode and the TM0 mode, and the second end c2 of the tapered waveguide is coupled to the input end of the mode coupling region 11; the tapered waveguide gradually widens from the first end c1 to the second end c2 to convert the TM0 mode in the input light into the TE1 mode, and then input the TE1 mode and the original TE0 mode in the input light into the mode coupling region 11.
[0035] Specifically, after the input light enters the tapered waveguide, the effective refractive index of the TM0 mode in the input light in the tapered waveguide is related to one or more factors such as the refractive index of the tapered waveguide material, the refractive indices of the upper cladding and the lower cladding of the tapered waveguide, the width difference (i.e., the widening amplitude) between the second end c2 and the first end c1 of the tapered waveguide, and the length of the tapered waveguide.
[0036] Among them, the effective refractive index of light in the waveguide refers to the ratio of the propagation constant of light to the wavenumber in vacuum, which can be used to describe the propagation speed and direction of light in the waveguide. The effective refractive index (neff) can be calculated by the propagation constant β and the speed of light c in vacuum: neff = c / β.
[0037] Furthermore, the refractive index of the upper cladding of the tapered waveguide is greater than that of the lower cladding.
[0038] Furthermore, the width difference △H between the width of the second end c2 and the width of the first end c1 of the tapered waveguide is greater than or equal to a first preset threshold; the length L of the tapered waveguide is greater than or equal to a second preset threshold; wherein, the larger the width difference, the larger the second preset threshold. In other words, the length L of the tapered waveguide is positively correlated with the width difference △H.
[0039] In the embodiment of the present invention, by setting the tapered waveguide to meet the above conditions, on the one hand, the effective refractive index of the TM0 mode in the input light can gradually increase from the first end c1 to the second end c2 of the tapered waveguide, making the effective refractive index of the TM0 mode approach the effective refractive index of the TE1 mode, thereby causing a mode hybridization phenomenon to be converted into the TE1 mode, and the converted TE1 mode is output from the second end c2 of the tapered waveguide to the mode coupling region 11. On the other hand, the original TE0 mode in the input light remains almost unchanged during the process of the tapered waveguide and can be considered to be output to the mode coupling region 11 in the "original TE0 mode".
[0040] It should be noted that the process of the width of the tapered waveguide changing with the length should preferably be a smooth gradual change process, so as to ensure that the mode hybridization effect in the tapered waveguide proceeds smoothly with the change of the length, thereby reducing the loss of mode hybridization. In addition, in this application, if a mode hybridization phenomenon is to occur, the width difference △H between the width of the second end c2 and the width of the first end c1 of the tapered waveguide should be greater than or equal to a certain threshold (i.e., the first preset threshold); if the width difference △H is too small, the expected mode hybridization phenomenon may not occur, that is, the conversion from the TM0 mode to the TE1 mode cannot be achieved.
[0041] It should be further noted that the first preset threshold cannot be set too small, otherwise the width difference △H may be too small, resulting in the effective refractive index of the original TM0 mode in the input light not being able to approach the effective refractive index of the TE1 mode, thereby preventing the occurrence of the mode hybridization phenomenon; the first preset threshold cannot be set too large, otherwise the required length of the tapered waveguide will be too large, making the transmission length of light in the tapered waveguide too long, thereby introducing unnecessary transmission losses.
[0042] Accordingly, the second preset threshold cannot be set too small, otherwise the effective refractive index of the TM0 mode cannot smoothly and adiabatically approach the effective refractive index of the TE1 mode, resulting in excessive loss during the mode hybridization process; the second preset threshold cannot be set too large, otherwise the transmission length of light in the tapered waveguide is too long, thereby introducing unnecessary transmission loss.
[0043] As a non-limiting embodiment, the wavelength λ of the input light is selected from [1280 nm, 1340 nm], the first preset threshold can be selected from the interval [0.4 μm, 1 μm], and the second preset threshold can be selected from the interval [340 μm, 350 μm]; the width of the first end c1 of the tapered waveguide can be selected from the interval [0.8 μm, 1.2 μm], for example, 1 μm; the width of the second end c2 of the tapered waveguide can be selected from the interval [1.4 μm, 1.8 μm], for example, 1.6 μm; the length of the tapered waveguide can be set to 350 μm, for example.
[0044] Furthermore, the tapered waveguide can be set as a symmetric broadening structure to minimize the introduction of noise as much as possible.
[0045] It should be noted that in the embodiments of the present invention, the mode hybridization region 10 can be implemented not only by using the tapered waveguide, but also by using other suitable structures capable of realizing the mode hybridization effect. For example, a ridge waveguide structure or a stepped waveguide structure, but compared with the tapered waveguide of the embodiments of the present invention, the process complexity of the foregoing two waveguide structures is higher.
[0046] Furthermore, in combination with Figure 2 and Figure 3 , Figure 2 is Figure 1 a schematic structural diagram of a specific structure of the mode coupling region 11 of the optical polarizer shown, Figure 3 is Figure 1 a schematic coupling structure diagram of the mode hybridization region 10 and the mode coupling region 11 of the optical polarizer shown.
[0047] Specifically, the mode coupling region 11 is formed with a first dual waveguide structure, and the first dual waveguide structure includes a first waveguide 111 and a second waveguide 112; a first end d1 of the first waveguide 111 is coupled to a second end c2 of the conical waveguide, and a second end of the first waveguide 111 (i.e., a first output end a1 of the mode coupling region 11) is coupled to a first input end b1 of the optical beam combining region 12; wherein, the first end d1 of the first waveguide 111 is configured to receive the original TE0 mode output from the second end c2 of the conical waveguide and then output from the second end of the first waveguide 111; a first end d2 of the second waveguide 112 is misaligned and coupled to the second end c2 of the conical waveguide, and a second end of the second waveguide 112 (i.e., a second output end a2 of the mode coupling region 11) is coupled to a second input end b2 of the optical beam combining region 12, wherein, the first end d2 of the second waveguide 112 converts the TE1 mode output from the second end c2 of the conical waveguide into coupled light of the TE0 mode and then outputs from the second end of the second waveguide 112.
[0048] In an embodiment of the present invention, the main function or technical effect of the mode coupling region 11 is as follows:
[0049] The second end c2 of the conical waveguide outputs optical signals of two modes, namely the "original TE0 mode" in the input light and the "converted TE1 mode" obtained by converting the original TM0 mode in the input light; wherein, the "original TE0 mode" is input from the first end d1 of the first waveguide 111 into the first waveguide 111 and then output from the second end of the first waveguide 111 (i.e., a1), and the "original TE0 mode" can also be approximately considered to remain unchanged in the first waveguide; the "converted TE1 mode" undergoes a coupling and mode conversion phenomenon at the input end of the first dual waveguide structure: it is coupled from the first end d1 of the first waveguide 111 into the first end d2 of the second waveguide 112, and is converted into the TE0 mode at the first end d2 of the second waveguide 112 and then output from the second end of the second waveguide 112 (i.e., a2).
[0050] In a specific implementation, the first end d1 of the first waveguide 111 and the first end d2 of the second waveguide 112 satisfy the following conditions:
[0051] Neff1_TE1×R1 = Neff2_TE0×R2;
[0052] Among them, Neff1_TE1 represents the effective refractive index of the TE1 mode at the first end d1 of the first waveguide 111, R1 represents the bending radius of the first end d1 of the first waveguide 111, Neff2_TE0 represents the effective refractive index of the TE0 mode at the first end d2 of the second waveguide 112, and R2 represents the bending radius of the first end d2 of the second waveguide 112.
[0053] In a specific implementation, the first end d1 of the first waveguide 111 and the second end d2 of the second waveguide 112 can be set to be parallel to each other. The shapes of the first end d1 of the first waveguide 111 and the second end d2 of the second waveguide 112 can be set to be straight strips or arcs; among them, in the case of being set to straight strips, the bending radii of the first end d1 of the first waveguide 111 and the second end d2 of the second waveguide 112 are the same and approximately infinite.
[0054] It should be noted that when the materials of the first waveguide 111 and the second waveguide 112 are the same, to meet the above equation conditions, the widths H1 of the first end d1 of the first waveguide 111 and H2 of the first end d2 of the second waveguide 112 satisfy the following conditions in different cases:
[0055] Case 1: The first end d1 of the first waveguide 111 and the first end d2 of the second waveguide 112 are straight strip structures parallel to each other, then it satisfies: H1 > H2;
[0056] Case 2: The first end d1 of the first waveguide 111 and the first end d2 of the second waveguide 112 are arc structures parallel to each other. Since the bending radius R1 of the first end d1 of the first waveguide 111 > the bending radius of the first end d2 of the second waveguide 112, then H1 > H2 or H1 ≤ H2.
[0057] As a non-limiting embodiment, the wavelength λ of the input light is selected from [1280 nm, 1340 nm], the width of the first end d1 of the first waveguide 111 can be selected from the interval [1.5 μm, 1.8 μm], for example, 1.6 μm; the width of the first end d2 of the second waveguide 112 can be selected from the interval [0.62 μm, 0.66 μm], for example, 0.64 μm.
[0058] Furthermore, the distance gap1 between the first end d1 of the first waveguide 111 and the first end d2 of the second waveguide 112 is less than the distance gap2 between the second end of the first waveguide 111 (i.e., the first output end a1 of the mode coupling region 11) and the second end of the second waveguide 112 (i.e., the second output end a2 of the mode coupling region 11).
[0059] In a specific implementation, the spacing gap1 to gap2 can be set to gradually increase. For example, an arc waveguide section 1121 can be provided between the first end d2 and the second end of the second waveguide 112. Compared with using a folded waveguide section or other waveguide sections with sharp corners, which makes the spacing gap2 greater than gap1, the use of the arc waveguide section 1112 in this implementation can effectively reduce optical power loss.
[0060] In the embodiment of the present invention, by setting the waveguide spacing of the first double-waveguide structure to increase from the first end to the second end, it is possible to effectively separate the "original TE0 mode" received from the second end c2 of the conical waveguide and the "converted TE0 mode" formed by conversion, and prevent the converted TE0 mode in the first end d2 of the second waveguide 112 from coupling back into the first waveguide 111 again, causing optical signal interference with each other.
[0061] It should be noted that in the embodiment of the present invention, the mode coupling region 11 can be implemented not only by Figure 2 the first double-waveguide structure shown, but also by other suitable structures that can achieve similar functions. For example, a Y-branch waveguide structure can be used. However, compared with the first double-waveguide structure provided in the embodiment of the present invention, the Y-branch waveguide structure has lower process tolerance.
[0062] Furthermore, the optical polarizer may further include a phase compensation region 13.
[0063] Specifically, the first input end e1 of the phase compensation region 13 is coupled to the second end of the first waveguide 111, and the second input end e2 of the phase compensation region 13 is coupled to the second end of the second waveguide 112; the first output end f1 of the phase compensation region 13 is coupled to the first input end b1 of the optical beam combining region 12, and the second output end f2 of the phase compensation region 13 is coupled to the second input end b2 of the optical beam combining region 12.
[0064] Among them, the phase compensation region 13 is used to perform phase compensation on the "converted TE0 mode" output from the second end of the second waveguide 112, so that the phase-compensated TE0 mode is in phase with the "original TE0 mode" output from the second end of the first waveguide 111, and then the two in-phase TE0 modes are input into the optical beam combining region 12.
[0065] In a specific implementation, the phase compensation region can adopt a mutually symmetric curved double-waveguide structure (as Figure 1 shown), or other existing structures that can achieve phase compensation can also be used. The embodiment of the present invention does not make any limitations.
[0066] Further, the optical polarizer may further include a second dual-waveguide structure 14, and the second dual-waveguide structure 14 includes a third waveguide 141 and a fourth waveguide 142; a first end g1 of the third waveguide 141 is coupled to a second end of the first waveguide 111, and a second end g2 of the third waveguide 141 is coupled to a first input end e1 of the phase compensation region 13; a first end h1 of the fourth waveguide 142 is coupled to a second end of the second waveguide 112, and a second end h2 of the fourth waveguide 142 is coupled to a second input end e2 of the phase compensation region 13; the width of the second end g2 of the third waveguide 141 is the same as the width of the second end h2 of the fourth waveguide 142.
[0067] Specifically, the second dual-waveguide structure may be referred to as a "mode evolution region". As described above, in a specific implementation, since the width H1 of the first end d1 of the first waveguide 111 may be set to be greater than the width H2 of the first end d2 of the second waveguide 112, therefore, in the embodiments of the present invention, by providing the second dual-waveguide structure, it is ensured that the width of the waveguide output end for outputting the "original TE0 mode" (i.e., the width of the second end g2 of the third waveguide 141) is the same as the width of the waveguide output end for outputting the "converted TE0 mode" (i.e., the width of the second end h2 of the fourth waveguide 142). Thus, it is possible to achieve better effects of subsequent phase compensation and beam combining for the "converted TE0 mode" and the "original TE0 mode", further effectively reducing optical power loss and achieving full utilization of the input light.
[0068] It should be noted that during the process of hybridizing the original TE0 mode in the input light by the mode hybridization region 10 to obtain the TE1 mode, during the process of converting the TE1 mode received from the mode hybridization region to the TE0 mode by the mode coupling region 11, and during the process of mode evolution by the above-mentioned second dual-waveguide structure, additional phases may be introduced. For example, the TE1 mode output by the mode hybridization region 10 has an additional phase φ h , and the "converted TE0 mode" output by the mode coupling region 11 has an additional phase φ h on the basis of this, and also has an additional phase φ c . The "converted TE0 mode" output by the fourth waveguide 142 of the second dual-waveguide structure has an additional phase φ h and φ c on the basis of this, and also has an additional phase φ e .
[0069] Therefore, in the embodiments of the present invention, by providing a phase compensation region 13 between the mode coupling region 11 and the optical beam combining region 12, it is used to perform phase compensation on the "converted TE0 mode". Thus, it is possible to achieve the same phase of the "converted TE0 mode" and the "original TE0 mode" finally input into the optical beam combining region 12, making the optical beam combining effect better, minimizing the optical power loss, and improving the utilization rate of the input light.
[0070] In a specific implementation, the optical polarizer may further include an optical input region (not shown in the figure), and the output end of the optical input region is coupled to the first end c1 of the conical waveguide; wherein, after the input light enters the optical input region, it outputs from the output end of the optical input region to the conical waveguide in two modes of TE0 and TM0.
[0071] The optical polarizer may further include an optical output region (not shown in the figure), and the optical output region is coupled to the output end of the optical beam combining region 12, and is used to receive the combined optical signal from the optical beam combining region 12 and output it.
[0072] In a specific implementation, Figure 1 The shown optical polarizer can be implemented by a chip integration scheme. For example, the mode hybridization region 10, the mode coupling region 11, and the optical beam combining region 12 can be formed on a single chip. More specifically, the waveguide structures of each functional region or unit can be formed on a single chip by a conventional etching process to achieve high integration of the device, reduce the device size, and at the same time reduce the optical power loss.
[0073] More specifically, the waveguide materials of each functional region in the present application can be selected from one or more of the following: waveguide materials used in the field of integrated optics such as silicon, silicon dioxide, silicon nitride, thin film lithium niobate, III-V materials, polymers, etc., for example, silicon nitride. Among them, the upper cladding material and the lower cladding material of the conical waveguide can be cladding materials used in the field of integrated optics such as silicon dioxide, air, silicon nitride, etc., for example, the upper cladding is air and the lower cladding is silicon dioxide.
[0074] The embodiments of the present invention further provide a fiber optic gyroscope, including Figure 1 The shown optical polarizer.
[0075] Furthermore, the fiber optic gyroscope may further include an optical fiber loop (for example, a polarization-maintaining optical fiber loop), and the optical fiber loop is used to receive the combined optical signal output by the optical polarizer, that is, the optical signal obtained by combining the "original TE0 mode" and the "converted TE0 mode" in the input light. Among them, the combined optical signal undergoes the Sagnac effect in the optical fiber loop and then returns to be input into the optical polarizer.
[0076] By applying the optical polarizer provided in this embodiment to a fiber optic gyroscope, an optical signal with smaller power loss, lower polarization crosstalk, and almost no stray TM light can be output to the fiber optic loop, thereby improving the performance of the fiber optic gyroscope and achieving higher measurement accuracy.
[0077] It should be understood that the term "and / or" in this article is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article indicates that the associated objects before and after are in an "or" relationship.
[0078] The term "a plurality of" appearing in the embodiments of this application refers to two or more.
[0079] The descriptions such as the first and the second appearing in the embodiments of this application are only for schematic and distinguishing the described objects, without an order, nor do they represent a special limitation on the number of devices in the embodiments of this application, and cannot constitute any limitation to the embodiments of this application.
[0080] It should be noted that the sequence numbers of the various steps in this embodiment do not represent the limitation of the execution sequence of the various steps.
[0081] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.
Claims
1. An optical polarizer, characterized in that, Comprising: A mode hybrid region, a mode coupling region, and a photosynthetic beam region; The input end of the mode coupling region is coupled to the output end of the mode hybrid region, and the first output end and the second output end of the mode coupling region are respectively coupled to the first input end and the second input end of the photosynthetic beam region; Wherein, the mode hybrid region is used to receive input light containing TE0 mode and TM0 mode, convert the TM0 mode into TE1 mode, and then input the TE1 mode and the original TE0 mode in the input light into the mode coupling region; The mode coupling region is used to output the original TE0 mode received from the first output end of the mode coupling region, and is used to convert the received TE1 mode into TE0 mode, and then output the converted TE0 mode from the second output end of the mode coupling region; The photosynthetic beam region is used to receive the two beams of TE0 mode output from the first output end and the second output end of the mode coupling region and perform beam combining processing.
2. The optical polarizer according to claim 1, characterized in that, The mode hybrid region is formed with a tapered waveguide, the first end of the tapered waveguide is used to receive input light containing TE0 mode and TM0 mode, and the second end of the tapered waveguide is coupled to the input end of the mode coupling region; The tapered waveguide gradually widens from the first end to the second end to convert the TM0 mode in the input light into TE1 mode, and then input the TE1 mode and the original TE0 mode in the input light into the mode coupling region.
3. The optical polarizer according to claim 2, characterized in that, The refractive index of the upper cladding of the tapered waveguide is greater than the refractive index of the lower cladding.
4. The optical polarizer according to claim 2 or 3, characterized in that, The width difference between the width of the second end and the width of the first end of the tapered waveguide is greater than or equal to a first preset threshold; The length of the tapered waveguide is greater than or equal to a second preset threshold; Wherein, the greater the width difference, the greater the second preset threshold.
5. The optical polarizer according to claim 2, characterized in that, The mode coupling region is formed with a first double waveguide structure, and the first double waveguide structure includes a first waveguide and a second waveguide; The first end of the first waveguide is coupled to the second end of the tapered waveguide, and the second end of the first waveguide is coupled to the first input end of the photosynthetic beam region. Wherein, the first end of the first waveguide is used to receive the original TE0 mode output from the second end of the tapered waveguide and then output it from the second end of the first waveguide; The first end of the second waveguide is misaligned and coupled to the second end of the tapered waveguide, and the second end of the second waveguide is coupled to the second input end of the photosynthetic beam region. Wherein, the first end of the second waveguide forms coupled light of TE0 mode based on the TE1 mode output from the second end of the tapered waveguide and then outputs it from the second end of the second waveguide.
6. The optical polarizer according to claim 5, characterized in that, The first end of the first waveguide and the first end of the second waveguide satisfy the following conditions: Neff1_TE1×R1=Neff2_TE0×R2; Among them, Neff1_TE1 represents the effective refractive index of the TE1 mode at the first end of the first waveguide, R1 represents the bending radius of the first end of the first waveguide, Neff2_TE0 represents the effective refractive index of the TE0 mode at the first end of the second waveguide, and R2 represents the bending radius of the first end of the second waveguide.
7. The optical polarizer according to claim 5 or 6, characterized in that, The spacing between the first end of the first waveguide and the first end of the second waveguide is smaller than the spacing between the second end of the first waveguide and the second end of the second waveguide.
8. The optical polarizer according to claim 5, characterized in that, The optical polarizer further includes a phase compensation region; The first input end of the phase compensation region is coupled to the second end of the first waveguide, and the second input end of the phase compensation region is coupled to the second end of the second waveguide; The first output end of the phase compensation region is coupled to the first input end of the optical beam combining region, and the second output end of the phase compensation region is coupled to the second input end of the optical beam combining region; Among them, the phase compensation region is used to perform phase compensation on the TE0 mode output from the second end of the second waveguide, so that the phase-compensated TE0 mode has the same phase as the TE0 mode output from the second end of the first waveguide, and then the two beams of TE0 modes with the same phase are input into the optical beam combining region.
9. The optical polarizer according to claim 8, characterized in that, The optical polarizer further includes a second dual-waveguide structure, and the second dual-waveguide structure includes a third waveguide and a fourth waveguide; The first end of the third waveguide is coupled to the second end of the first waveguide, and the second end of the third waveguide is coupled to the first input end of the phase compensation region; The first end of the fourth waveguide is coupled to the second end of the second waveguide, and the second end of the fourth waveguide is coupled to the second input end of the phase compensation region; The width of the second end of the third waveguide is the same as the width of the second end of the fourth waveguide.
10. An optical fiber gyroscope, characterized in that, Including the optical polarizer according to any one of claims 1 to 9.