Polarization maintaining isolator and optical device
By setting a combination of a first collimator, a first polarizer, a Faraday rotator, and a second polarizer in the optical isolator, the polarization rotation of light is achieved by using the Faraday rotator, which solves the cost and space problems caused by the reliance on half-wave plates in the existing optical isolator, and realizes a compact design and low-loss conduction effect.
Patent Information
- Application Number
- CN202610420274.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-01
- Publication Date
- 2026-06-02
AI Technical Summary
Existing optical isolators in polarization-maintaining fiber systems rely on half-wave plates as reciprocal rotating elements, which increases material costs and assembly processes, and is not conducive to device miniaturization.
The structure is designed with a first collimator, a first polarizer, a Faraday rotator, a second polarizer, and a second collimator arranged sequentially along the optical path. The Faraday rotator is used as the only non-reciprocal rotating element to achieve polarization rotation of the light, thus avoiding the need for an additional optical rotator.
A compact design for the optical isolator has been achieved, simplifying the device structure and reducing the space occupied by the device, while realizing low-loss conduction of forward optical signals and effective blocking of reverse optical signals.
Smart Images
Figure CN122131442A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical devices, and in particular to a polarization-maintaining isolator and optical equipment. Background Technology
[0002] An optical isolator is a passive optical device widely used in fiber lasers, fiber optic communications, and optical sensing. Its main function is to allow light signals to pass through with low loss in the forward propagation direction while effectively blocking light propagating in the reverse direction, thereby protecting the light source and front-end systems from interference or damage caused by reflected light. In polarization-maintaining fiber systems, the optical isolator must also maintain the stability of the polarization state of the transmitted light to ensure the reliability of the system's polarization-dependent performance.
[0003] However, optical isolators in related technologies usually rely on half-wave plates as reciprocal rotating elements, which not only increases material costs and assembly processes but also hinders device miniaturization. Summary of the Invention
[0004] Based on this, embodiments of this application provide a polarization-maintaining isolator and optical device, which can simplify the device structure and reduce the space occupied by the device, thereby achieving a compact design of the optical isolator.
[0005] To achieve the above objectives, some embodiments of this application provide a polarization-maintaining isolator. This isolator includes a first collimator, a first polarizer, a Faraday rotator, a second polarizer, and a second collimator arranged sequentially along the optical path direction; wherein the transmission axis of the first polarizer is along a first target polarization direction; the Faraday rotation angle of the Faraday rotator is equal to the target angle; the transmission axis of the second polarizer is along a second target polarization direction; the first target polarization direction, after being rotated by the target angle, is aligned with the second target polarization direction; and the second target polarization direction, after being rotated by the target angle, is perpendicular to the first target polarization direction.
[0006] In some embodiments, the first collimator is used to receive positive light rays; wherein, the first collimator is configured to convert the positive light rays into positive input collimated light rays; the first polarizer is configured to convert the positive collimated light rays into initial positive polarized light with a first target polarization direction; the Faraday rotator is configured to rotate the initial positive polarized light by the target angle to obtain target positive polarized light with a second target polarization direction; the second polarizer is configured to transmit the target positive polarized light; and the second collimator is configured to convert the target positive polarized light into positive output collimated light rays and output them.
[0007] In some embodiments, the second collimator is used to receive reverse light rays; wherein the second collimator is configured to convert the reverse light rays into reverse input collimated light rays; the second polarizer is configured to convert the reverse input collimated light rays into initial reverse polarized light with a second target polarization direction; the Faraday rotator is configured to rotate the initial reverse polarized light rays by the target angle to obtain target reverse polarized light with a third target direction; the third target direction is perpendicular to the first target polarization direction; and the first polarizer is configured to block the target reverse polarized light.
[0008] In some embodiments, the Faraday rotator includes a magneto-optical crystal, a first magnetic group, and a second magnetic group; wherein the magneto-optical crystal is located between the first polarizer and the second polarizer in the optical path direction; the first magnetic group and the second magnetic group are located on opposite sides of the magneto-optical crystal in a direction perpendicular to the optical path; and the magneto-optical crystal is located in the magnetic field region between the first magnetic group and the second magnetic group.
[0009] In some embodiments, the target angle is an odd multiple of 45°.
[0010] In some embodiments, the working axis direction of the first collimator is consistent with the transmission axis direction of the first polarizer.
[0011] In some embodiments, the working axis direction of the second collimator is consistent with the transmission axis direction of the second polarizer.
[0012] In some embodiments, the first collimator and / or the second collimator are polarization-maintaining fiber collimators.
[0013] In some embodiments, the first polarizer and / or the second polarizer is a polarizing beam splitter.
[0014] On the other hand, this application also provides an optical device according to some embodiments; the optical device includes a polarization-maintaining isolator as described in any of the embodiments in the preceding aspect of this application.
[0015] The embodiments of this application may have, or at least have, the following advantages:
[0016] In this embodiment, a first collimator, a first polarizer, a Faraday rotator, a second polarizer, and a second collimator are sequentially arranged along the optical path. First, by rotating the first target polarization direction of the first polarizer by a target angle to align it with the second target polarization direction of the second polarizer, positive light incident from the first collimator along the optical path becomes polarized in the first target direction after passing through the first polarizer. Then, after being rotated by the Faraday rotator by a target angle, it becomes polarized in the second target direction, allowing the positive light to pass through the second polarizer and be transmitted to the second collimator for output. Furthermore, by rotating the second target polarization direction by a target angle to make it perpendicular to the first target polarization direction, reverse light incident from the second collimator along the optical path becomes polarized in the second target direction after passing through the second polarizer. Then, after being rotated by the Faraday rotator by a target angle, it becomes perpendicular to the first target polarization direction of the first polarizer, thus blocking the reverse light. With the combined effect of the above technical features, this application enables the Faraday rotator to independently achieve polarization rotation of light as the only non-reciprocal rotation element. This allows for low-loss conduction of forward light signals and effective blocking of reverse light signals without the need for additional optical rotators, which helps to simplify the equipment structure and reduce the space occupied by the equipment, thus enabling a compact design of the optical isolator.
[0017] Details of one or more embodiments of this application are set forth in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a schematic diagram of a polarization-maintaining isolator provided in some embodiments.
[0020] Explanation of reference numerals in the attached figures:
[0021] 1-First collimator, 2-First polarizer, 3-Faraday rotator, 31-Magnet-optical crystal, 32-First magnetic group, 33-Second magnetic group, 4-Second polarizer, 5-Second collimator. Detailed Implementation
[0022] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate preferred embodiments of the application. However, this application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.
[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
[0024] It should be understood that when an element or layer is referred to as being "on," "adjacent to," or "connected to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, regions, layers, doping types, and / or portions, these elements, components, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type, or portion from another element, component, region, layer, doping type, or portion. Therefore, without departing from the teachings of this application, the first element, component, region, layer, doping type, or portion discussed below may be referred to as a second element, component, region, layer, or portion.
[0025] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms “comprise” and / or “comprising” are used in this specification, the presence of the stated feature, integer, step, operation, element, and / or part is established, but the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups is not excluded. Meanwhile, when used herein, the term “and / or” includes any and all combinations of the associated listed items.
[0026] Embodiments of the invention are described herein with reference to cross-sectional views illustrating preferred embodiments (and intermediate structures) of this application, thus allowing for the anticipation of variations in the illustrated shapes due to, for example, manufacturing techniques and / or tolerances. Embodiments of this application should not be limited to the specific shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing techniques. Therefore, the regions shown in the figures are substantially schematic, and their shapes do not represent the actual shapes of regions of the device, nor do they limit the scope of this application.
[0027] This application provides a polarization-maintaining isolator and optical device that can simplify the device structure and reduce the space occupied by the device, thereby achieving a compact design of the optical isolator.
[0028] In some embodiments, please refer to Figure 1 The polarization-maintaining isolator includes a first collimator 1, a first polarizer 2, a Faraday rotator 3, a second polarizer 4, and a second collimator 5 arranged sequentially along the optical path direction; wherein, the transmission axis of the first polarizer 2 is along the first target polarization direction; the Faraday rotation angle of the Faraday rotator 3 is equal to the target angle; the transmission axis of the second polarizer 4 is along the second target polarization direction; the first target polarization direction, after being rotated by the target angle, is consistent with the second target polarization direction; the second target polarization direction, after being rotated by the target angle, is perpendicular to the first target polarization direction.
[0029] For example, the first polarizer 2 and / or the second polarizer 4 include, but are not limited to, a polarizing beam splitter (PBS).
[0030] For example, the polarization direction of the first target can be horizontal (0°).
[0031] In some embodiments, the target angle is an odd multiple of 45°.
[0032] For example, the target angle could be 45° or -45°, etc.
[0033] For example, the polarization direction of the second target can be 45° or -45°, etc.
[0034] It should be noted that since the polarization direction of the first target is consistent with the polarization direction of the second target after rotating the target angle, when the polarization direction of the first target is horizontal (0°), the polarization direction of the second target is the same as the target angle.
[0035] In this embodiment, a first collimator 1, a first polarizer 2, a Faraday rotator 3, a second polarizer 4, and a second collimator 5 are sequentially arranged along the optical path. First, by rotating the first target polarization direction of the first polarizer 2 by a target angle to align it with the second target polarization direction of the second polarizer 4, positive light incident from the first collimator 1 along the optical path becomes polarized in the first target direction after passing through the first polarizer 2. Then, after being rotated by the Faraday rotator 3 by a target angle, it becomes polarized in the second target direction, allowing the positive light to pass through the second polarizer 4 and be transmitted to the second collimator 5 for output. Furthermore, by rotating the second target polarization direction by a target angle to make it perpendicular to the first target polarization direction, reverse light incident from the second collimator 5 along the optical path becomes polarized in the second target direction after passing through the second polarizer 4. Then, after being rotated by the Faraday rotator 3 by a target angle, it becomes perpendicular to the first target polarization direction of the first polarizer 2, thus blocking the reverse light. Under the combined effect of the above technical features, this application enables the Faraday rotator 3 to independently realize the polarization rotation of light as the only non-reciprocal rotation element. This allows for low-loss conduction of forward light signals and effective blocking of reverse light signals without the need for additional optical rotators. This simplifies the equipment structure, reduces the space occupied by the equipment, and enables a compact design of the optical isolator.
[0036] In some embodiments, the working axis direction of the first collimator 1 is consistent with the transmission axis direction of the first polarizer 2.
[0037] For example, the working axis of the first collimator 1 can be a slow axis or a fast axis; specifically, the working axis of the first collimator 1 is a slow axis.
[0038] For example, the working axis direction of the first collimator 1 is the polarization direction of the first target; for example, it is the horizontal direction (0°).
[0039] In some embodiments, the working axis direction of the second collimator 5 is consistent with the transmission axis direction of the second polarizer 4.
[0040] For example, the working axis of the second collimator 5 can be a slow axis or a fast axis; specifically, the working axis of the second collimator 5 is a slow axis.
[0041] For example, the working axis direction of the second collimator 5 is the polarization direction of the second target; for example, it is 45° or -45°, etc.
[0042] In this embodiment, by aligning the working axis of the first collimator 1 with the transmission axis of the first polarizer 2, and aligning the working axis of the second collimator 5 with the transmission axis of the second polarizer 4, it is beneficial to achieve low-loss light transmission, realize polarization matching between the first collimator 1 and the first polarizer 2, and between the second collimator 5 and the second polarizer 4, and avoid coupling loss introduced by angular deviation.
[0043] It should be noted that when the polarization-maintaining isolator is in the forward direction, the forward light passes through the first collimator 1, the first polarizer 2, the Faraday rotator 3, the second polarizer 4, and the second collimator 5 in sequence.
[0044] In some embodiments, please continue reading Figure 1 The first collimator 1 is used to receive positive light rays; wherein, the first collimator 1 is configured to convert the positive light rays into positive input collimated light rays; the first polarizer 2 is configured to convert the positive collimated light rays into initial positive polarized light with a first target polarization direction; the Faraday rotator 3 is configured to rotate the initial positive polarized light with the target angle to obtain target positive polarized light with a second target polarization direction; the second polarizer 4 is configured to transmit the target positive polarized light; and the second collimator 5 is configured to convert the target positive polarized light into positive output collimated light rays and output them.
[0045] For example, the first collimator 1 and / or the second collimator 5 may include, but are not limited to, polarization-maintaining fiber collimators.
[0046] For example, the first collimator 1 includes a first polarization-maintaining fiber; the second collimator 5 includes a second polarization-maintaining fiber.
[0047] For example, when the polarization-maintaining isolator is in the forward direction, the first collimator 1 is used to convert the forward diverging light transmitted in the first polarization-maintaining fiber into a forward input collimated light; the second collimator 5 is used to convert the target forward polarized light received from the second polarizer 4 into a forward output collimated light to couple into the second polarization-maintaining fiber and output it in a collimated manner.
[0048] It should be noted that when the polarization maintaining isolator is in the forward direction, the first polarizer 2 acts as the input polarizer and the second polarizer 4 acts as the output polarizer.
[0049] For example, the positive input collimated light input through the first collimator 1 is converted into initially positively polarized light with horizontal polarization (0°) by the first polarizer 2; the initially positively polarized light is rotated by Faraday rotator 3 by -45° to form target positively polarized light with -45° polarization and is transmitted through the second polarizer 4, and finally output as positively polarized light with -45° polarization through the second collimator 5.
[0050] For example, the positive input collimated light input through the first collimator 1 is converted into horizontally polarized (0°) initial positive polarized light through the first polarizer 2; the initial positive polarized light is rotated 45° by the Faraday rotator 3 to form a target positive polarized light with 45° polarization and is transmitted through the second polarizer 4, and finally output as a positive output collimated light with 45° polarization through the second collimator 5.
[0051] It should be noted that when the polarization-maintaining isolator is in the case of reverse light transmission, the reverse light passes through the second collimator 5, the second polarizer 4, and the Faraday rotator 3 in sequence, and is blocked by the first polarizer 2.
[0052] In some embodiments, please continue reading Figure 1 The second collimator 5 is used to receive the reverse light; wherein, the second collimator 5 is configured to convert the reverse light into a reverse input collimated light; the second polarizer 4 is configured to convert the reverse input collimated light into initial reverse polarized light in a second target polarization direction; the Faraday rotator 3 is configured to rotate the initial reverse polarized light by the target angle to obtain target reverse polarized light in a third target direction; the third target direction is perpendicular to the first target polarization direction; the first polarizer 2 is configured to block the target reverse polarized light.
[0053] For example, when the polarization-maintaining isolator is in the case of reverse light transmission, the second collimator 5 is used to convert the reverse diverging light transmitted in the second polarization-maintaining fiber into reverse input collimated light. Since the first polarizer 2 blocks the target reverse polarized light, the first collimator 1 does not receive the reverse light signal.
[0054] It should be noted that when the polarization maintaining isolator is in the reverse direction, the second polarizer 4 acts as the input polarizer and the first polarizer 2 acts as the output polarizer.
[0055] For example, the reverse input collimated light input via the second collimator 5 is converted into initial reverse polarized light with a polarization of -45° by the second polarizer 4; the initial reverse polarized light is rotated by Faraday rotator 3 by -45° to form target reverse polarized light with a polarization of -90°; since the polarization direction (-90°) of the target reverse polarized light is perpendicular to the first target polarization direction (0° in the horizontal direction) of the transmission axis of the first polarizer 2, the first polarizer 2 blocks the target reverse polarized light with a polarization of -90°.
[0056] For example, the reverse input collimated light input via the second collimator 5 is converted into initial reverse polarized light with a polarization of 45° by the second polarizer 4; the initial reverse polarized light is rotated 45° by the Faraday rotator 3 to form target reverse polarized light with a polarization of 90°; since the polarization direction (90°) of the target reverse polarized light is perpendicular to the first target polarization direction (0° in the horizontal direction) of the transmission axis of the first polarizer 2, the first polarizer 2 blocks the 90° polarized target reverse polarized light.
[0057] In some embodiments, please continue reading Figure 1 The Faraday rotator 3 includes a magneto-optical crystal 31, a first magnetic group 32, and a second magnetic group 33; wherein, the magneto-optical crystal 31 is located between the first polarizer 2 and the second polarizer 4 in the optical path direction; the first magnetic group 32 and the second magnetic group 33 are respectively located on both sides of the magneto-optical crystal 31 in the direction perpendicular to the optical path; the magneto-optical crystal 31 is located in the magnetic field region between the first magnetic group 32 and the second magnetic group 33.
[0058] For example, the distance between the magneto-optical crystal 31 and the first magnetic group 32 in the direction perpendicular to the optical path is equal to the distance between the magneto-optical crystal 31 and the second magnetic group 33 in the direction perpendicular to the optical path.
[0059] For example, the first magnetic group 32 and the second magnetic group 33 are symmetrical about the magneto-optical crystal 31 in a direction perpendicular to the optical path.
[0060] For example, the first polarizer 2 and the second polarizer 4 are symmetrical about the magneto-optical crystal 31 in the optical path direction.
[0061] For example, the magneto-optical crystal 31 includes, but is not limited to, terbium gallium garnet (TGG) or terbium scandium aluminum garnet (TSAG).
[0062] This application also provides an optical device according to some embodiments, which includes the polarization-maintaining isolator in the above embodiments. The optical device also possesses all the technical advantages of the aforementioned polarization-maintaining isolator. It should be noted that the parts that are the same as or corresponding to the above embodiments can be referred to the corresponding descriptions of the above embodiments, and will not be described in detail below.
[0063] In the description of this specification, references to terms such as "some embodiments," "some examples," "exemplarily," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.
[0064] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.
[0065] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application.
Claims
1. A polarization-maintaining isolator, characterized in that, It includes a first collimator, a first polarizer, a Faraday rotator, a second polarizer, and a second collimator arranged sequentially along the optical path; wherein, The transmission axis of the first polarizer is along the polarization direction of the first target. The Faraday rotation angle of the Faraday rotator is equal to the target angle; The transmission axis of the second polarizer is along the polarization direction of the second target; After rotating the first target polarization direction by the target angle, it becomes consistent with the second target polarization direction; after rotating the second target polarization direction by the target angle, it becomes perpendicular to the first target polarization direction.
2. The polarization maintaining isolator according to claim 1, characterized in that, The first collimator is used to receive forward light; wherein, The first collimator is configured to convert the positive ray into a positive input collimated ray; The first polarizer is configured to convert the positively collimated ray into initially positively polarized light with a first target polarization direction; The Faraday rotator is configured to rotate the initial positively polarized light by the target angle to obtain target positively polarized light with a second target polarization direction; The second polarizer is configured to transmit the target positively polarized light; The second collimator is configured to convert the target positively polarized light into a positively output collimated light ray and output it.
3. The polarization-maintaining isolator according to claim 1, characterized in that, The second collimator is used to receive the reverse light; wherein, The second collimator is configured to convert the reversed ray into a reversed input collimated ray; The second polarizer is configured to convert the reverse input collimated ray into an initial reverse polarized ray with a second target polarization direction; The Faraday rotator is configured to rotate the initial reverse polarized light by the target angle to obtain target reverse polarized light in a third target direction; the third target direction is perpendicular to the first target polarization direction. The first polarizer is configured to block the target reverse-polarized light.
4. The polarization maintaining isolator according to claim 1, characterized in that, The Faraday rotator comprises a magneto-optical crystal, a first magnetic group, and a second magnetic group; wherein... The magneto-optical crystal is located between the first polarizer and the second polarizer in the optical path direction; The first magnetic group and the second magnetic group are located on opposite sides of the magneto-optical crystal in a direction perpendicular to the optical path; the magneto-optical crystal is located in the magnetic field region between the first magnetic group and the second magnetic group.
5. The polarization maintaining isolator according to claim 1, characterized in that, The target angle is an odd multiple of 45°.
6. The polarization maintaining isolator according to claim 1, characterized in that, The working axis direction of the first collimator is consistent with the transmission axis direction of the first polarizer.
7. The polarization-maintaining isolator according to claim 1, characterized in that, The working axis direction of the second collimator is consistent with the transmission axis direction of the second polarizer.
8. The polarization maintaining isolator according to claim 1, characterized in that, The first collimator and / or the second collimator are polarization-maintaining fiber collimators.
9. The polarization maintaining isolator according to claim 1, characterized in that, The first polarizer and / or the second polarizer is a polarizing beam splitter.
10. An optical device, characterized in that, Includes the polarization-maintaining isolator as described in any one of claims 1 to 9.