A low-cost integrated module for polarization-independent optical circulators and filters.
By integrating modular design and combining polarization beam splitters and Faraday rotators, the problems of large area occupation and high loss of traditional optical circulators and filter combinations are solved, and low-cost, high-isolation optical signal processing is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- FUJIAN HITRONICS TECH INC
- Filing Date
- 2025-05-29
- Publication Date
- 2026-05-26
AI Technical Summary
Traditional combinations of optical circulators and filters suffer from problems such as large footprint, high superposition loss, high cost, and insufficient single-stage isolation, making it difficult to meet the packaging requirements of high-speed optical modules.
A low-cost polarization-independent optical circulator and filter integrated module is adopted, including first and second collimators, circulator core and base. By using a combination of polarization beam splitter prism, Faraday rotator crystal and filter at a specific angle, collimation and polarization rotation of signal light are achieved. Two-stage isolation and wavelength division multiplexing are achieved by small-angle incident light.
The integration of optical circulators and filters has been achieved, reducing the number of optical components, lowering manufacturing costs, enhancing isolation, and enabling miniaturization and compact optical path layout of the device.
Smart Images
Figure CN224287289U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of optical fiber communication technology, specifically to a low-cost integrated module for a polarization-independent optical circulator and filter. Background Technology
[0002] The 800G / 1.6T high-speed optical module needs to solve the problems of signal crosstalk and insertion loss. Traditional discrete devices (such as optical circulators + filters) occupy a large area, which makes it difficult to meet the packaging requirements, have high superposition loss, and are costly. At present, the circulator function is mainly realized by the traditional PBS + Faraday rotation combination, and the filter function is realized by the large-angle Z-block. However, there are still problems of insufficient isolation of single pole and excessive size. Summary of the Invention
[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-cost integrated module for polarization-independent optical circulators and filters, which is suitable for optical signal processing in high-speed optical modules.
[0004] To achieve the above objectives, the present invention adopts the following technical solution:
[0005] A low-cost integrated module for a polarization-independent optical circulator and filter includes a first collimator, a circulator core, and a second collimator arranged in sequence.
[0006] The first collimator is a four-fiber collimator, with its four fibers designated as Port1-1, Port1-2, Port3-1, and Port3-2. Port1-1 is used to input short-wavelength signal light, Port1-2 is used to input long-wavelength signal light, Port3-1 is used to output short-wavelength signal light, and Port3-2 is used to output long-wavelength signal light. The first collimator is used to collimate the signal light. The angle between the signal light from Port1-1 and Port1-2 is 2A, the angle between the signal light from Port3-1 and Port3-2 is 2A, the angle between the signal light from Port1-1 and Port3-1 is 2A, and the angle between the signal light from Port1-2 and Port3-2 is 2A.
[0007] The second collimator is a single-fiber collimator used to collimate the signal light. The fiber of the second collimator is Port2. The second collimator is used to collimate the signal light output from Port1-1 and Port1-2 through the circulator core and couple it to Port2.
[0008] The circulator core includes a first polarizing beam splitter prism, a half-wave plate, a Faraday rotator crystal, a second polarizing beam splitter prism, a first filter, a first reflector, a second filter, a second reflector, and a magnetic block; the first polarizing beam splitter prism has a trapezoidal cross-section and a first polarizing beam splitting film inside; the second polarizing beam splitter prism has a trapezoidal cross-section and a second polarizing beam splitting film inside.
[0009] The right end face of the first polarizing beam splitter is attached to the left end face of the Faraday rotator crystal, and the right end face of the Faraday rotator crystal is attached to the left end face of the half-wave plate; the first polarizing beam splitter film is parallel to the lower end face of the first polarizing beam splitter; the left end face of the second polarizing beam splitter film is attached to the right end face of the half-wave plate, and the second polarizing beam splitter film is parallel to the upper end face of the second polarizing beam splitter; the first filter and the first reflector are located to the right of the second polarizing beam splitter, and the second filter and the second reflector are located to the lower side of the second polarizing beam splitter; the first filter and the second filter reflect long-wavelength signal light and transmit short-wavelength signal light; the included angle between the first filter and the first reflector is A; the included angle between the second filter and the second reflector is also A.
[0010] Furthermore, the present invention also includes a base, which is used to bond and fix the first collimator, the circulator core, and the second collimator.
[0011] Furthermore, the positions of the half-wave plate and the Faraday rotator crystal can be interchanged.
[0012] Furthermore, the value of angle A is less than 5 degrees.
[0013] The present invention adopts the above technical solution and has the following beneficial effects:
[0014] In this invention, the coordination of the first reflector, first filter, second reflector, second filter, and circulator core is key to achieving dual-stage isolation and wavelength division multiplexing / demultiplexing. The angles formed between the first reflector and first filter, and between the second reflector and second filter, match the output cross-angle of the first collimator, thus effectively realizing the circulator and wavelength division multiplexing functions during optical signal transmission. This design not only avoids unnecessary signal reflection and loss but also enhances the isolation of the optical circulator, achieving dual-stage isolation. It allows for wavelength division multiplexing through small-angle incident light, resulting in a more compact optical path layout, reducing the number of required optical components, lowering the coating requirements of the filters, and facilitating device miniaturization, thereby reducing device complexity and manufacturing costs. Attached Figure Description
[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:
[0016] Figure 1 This is a simplified front view of the overall structure of this utility model;
[0017] Figure 2 A schematic diagram showing the angle of the output light from the first collimator;
[0018] Figure 3 A simplified structural diagram of the circulator core;
[0019] Figure 4 This is a schematic diagram of the structure and optical path of the first filter and the first reflector;
[0020] Figure 5 This is a schematic diagram of the structure and optical path of the second filter and the second reflecting mirror.
[0021] Figure 6 This is a schematic diagram of the optical path from Port1-1 to Port2;
[0022] Figure 7 This is a schematic diagram of the optical path from Port1-2 to Port2;
[0023] Figure 8 This is a schematic diagram of the optical path from Port2 to Port3-1;
[0024] Figure 9 This is a schematic diagram of the optical path from Port2 to Port3-2. Detailed Implementation
[0025] like Figure 1-9 As shown, this utility model discloses a low-cost polarization-independent optical circulator and filter integrated module, the structure of which includes: a first collimator 101, a circulator core 102, a second collimator 103, and a base 104.
[0026] The first collimator 101 is a four-fiber collimator, with its four fibers designated as Port1-1, Port1-2, Port3-1, and Port3-2. Port1-1 is used to input short-wavelength signal light, Port1-2 is used to input long-wavelength signal light, Port3-1 is used to output short-wavelength signal light, and Port3-2 is used to output long-wavelength signal light. The first collimator 101 is used to collimate the signal light. The angle between the signal light at Port1-1 and Port1-2 is 2A, the angle between the signal light at Port3-1 and Port3-2 is 2A, the angle between the signal light at Port1-1 and Port3-1 is 2A, and the angle between the signal light at Port1-2 and Port3-2 is 2A.
[0027] The second collimator 103 is a single-fiber collimator used to collimate the signal light. The fiber of the second collimator 103 is the Port2 port. The second collimator 103 is used to collimate the signal light output from the Port1-1 port and the Port1-2 port through the circulator core and couple it to the Port2 port.
[0028] The base 104 is used to bond and fix the first collimator 101, the circulator core 102 and the second collimator 103, and plays a fixing role.
[0029] The circulator core 102 includes a first polarizing beam splitter 1021, a Faraday rotator crystal 1022, a half-wave plate 1023, a second polarizing beam splitter 1024, a first filter 1025, a first reflector 1026, a second filter 1027, a second reflector 1028, and a magnetic block 1029. The magnetic block 1029 provides a magnetic field, enabling the Faraday rotator crystal 1022 to rotate the polarization direction of the input light under the magnetic field. The first polarizing beam splitter 1021 has a trapezoidal cross-section and contains a first polarizing beam splitter film. The second polarizing beam splitter 1024 has a trapezoidal cross-section and contains a second polarizing beam splitter film. The first polarizing beam splitter 1021 and the second polarizing beam splitter 1024 are used to input or output collimated parallel light; the first polarizing beam splitter film and the second polarizing beam splitter film are used to separate or combine P-polarized light and S-polarized light in the signal light; the half-wave plate 1023, the Faraday rotator crystal 1022, and the magnetic block 1029 constitute an optical rotation combination for focusing on a single transmission direction (…). Figure 3 The signal light (from left to right) is polarized and rotated by 90°, while the signal light in the opposite direction (…) Figure 3 The signal light transmitted from right to left (in the middle) does not undergo polarization rotation.
[0030] The right end face of the first polarizing beam splitter 1021 is attached to the left end face of the Faraday rotator crystal 1022, and the right end face of the Faraday rotator crystal 1022 is attached to the left end face of the half-wave plate 1023. The end face of the first polarizing beam splitter film is parallel to the lower end face of the first polarizing beam splitter 1021. The second polarizing beam splitter film is parallel to the upper end face of the second polarizing beam splitter 1024. The first filter 1025 and the first reflector 1026 are located to the right of the second polarizing beam splitter 1024, and the second filter 1027 and the second reflector 1028 are located to the lower side of the second polarizing beam splitter 1024. The first filter 1025 and the second filter 1027 reflect long-wavelength signal light and transmit short-wavelength signal light.
[0031] The angle between the reflective surface of the first filter 1025 and the reflective surface of the first mirror 1026 is A, and the angle between the reflective surface of the second filter 1027 and the reflective surface of the second mirror 1028 is also A.
[0032] The angle A mentioned above is the same and its value ranges from less than 5 degrees. In this embodiment, the angle A is 2.2°.
[0033] The first collimator 101 outputs short-wavelength signal light and long-wavelength signal light respectively between its Port1-1 port and Port1-2 port at an angle of 2A. The (short-wavelength and long-wavelength) signal light is incident on the left end face of the first polarizing beam splitter 1021, refracted, and then transmitted to the first polarizing beam splitter film. The P-component of the signal light is transmitted through the first polarizing beam splitter, and then through the optical rotation combination composed of the Faraday rotator crystal 1022 and the half-wave plate 1023. Its polarization direction changes, and the P-light becomes the S-light. The S-light then enters the second polarizing beam splitter 1024, is reflected by the upper surface of the second polarizing beam splitter 1024, and is reflected again by the second polarizing beam splitter. It is then transmitted to the right end face of the second polarizing beam splitter 1024. The S-component of the signal light is reflected by the first polarizing beam splitter, then by the lower surface of the first polarizing beam splitter. It then passes through the optical rotation combination composed of the Faraday rotator crystal and the half-wave plate, changing its polarization direction again. The S-light becomes the P-light, and then enters the second polarizing beam splitter 1024, is transmitted, and is transmitted to the right end face of the second polarizing beam splitter 1024. Finally, the P-light and S-light components are combined at the right end face of the second polarizing beam splitter.
[0034] The short-wavelength signal light from Port1-1 is transmitted through the first filter 1025, reflected by the first reflector 1026, and then transmitted through the first optical filter 1025 again. The long-wavelength signal light from Port1-2 is reflected by the rear end face of the first filter 1025. By setting the angle between the first filter 1025 and the first reflector 1026 to A, the light output from Port1-1 after being reflected by the first reflector 1026 and the light output from Port1-2 after being reflected by the first filter 1025 are combined, and the light output from Port1-1 and the light output from Port1-2 form an angle 2A between each pair of the long-wavelength reflection end face of the first filter 1025.
[0035] The combined signal light is transmitted to the left to the second polarizing beam splitter. The P-beam is transmitted, and the S-beam is reflected. The S-beam is reflected by the upper surface of the second polarizing beam splitter 1024. After passing through the half-wave plate 1023 and the Faraday rotator crystal 1022 respectively, the polarization directions of the P-beam and S-beam remain unchanged. The P-beam enters the first polarizing beam splitter 1021, is reflected by the lower surface of the first polarizing beam splitter 1021, and is transmitted through the first polarizing beam splitter. The S-beam enters the first polarizing beam splitter 1021, is reflected by the first polarizing beam splitter, and the two beams are combined and transmitted upward to the upper surface of the first polarizing beam splitter 1021, where they are reflected. The beam is then transmitted to the right side of the first polarizing beam splitter 1021, then to the second collimator 103, and finally to Port2.
[0036] The signal light input from Port2, pointing to the left, is incident on the right end face of the first polarizing beam splitter 1021. It is refracted and then transmitted to the upper end face of the first polarizing beam splitter 1021 before being reflected. It then travels to the first polarizing film. The P-ray in the signal light is transmitted through the first polarizing film and then reflected at the lower end face of the first polarizing beam splitter 1021. After passing through the combination of the Faraday rotator crystal 1022 and the half-wave plate 1023, the polarization direction of the P-ray changes, becoming the S-ray. The S-ray then enters the second polarizing beam splitter 1024, is reflected by the second polarizing film, and travels downwards to the second polarizing film. The lower end face of the polarizing beam splitter 1024; the S-beam in the signal light is reflected at the first polarizing beam splitter film, and then transmitted to the right side of the first polarizing beam splitter 1021. After the S-beam passes through the combination of the Faraday rotator crystal 1022 and the half-wave plate 1023, the polarization direction of the S-beam changes, and the S-beam becomes the P-beam. Then the P-beam enters the second polarizing beam splitter 1024, and is then transmitted to the upper end face of the second polarizing beam splitter 1024 for reflection. It is then transmitted through the second polarizing beam splitter film and transmitted downward to the lower end face of the second polarizing beam splitter 1024. Then the P-beam and the S-beam are combined and transmitted downward to the lower end face of the second polarizing beam splitter 1024.
[0037] The long-wavelength signal light input from Port2 is reflected after passing through the second filter 1027; the short-wavelength signal light is transmitted after passing through the second filter 1027, then reflected by the second mirror 1028, and then transmitted after passing through the second filter 1027 again; by setting the angle between the second filter 1027 and the second mirror 1028 to A, the light transmitted from Port2 to the second filter 1027, the short-wavelength signal light transmitted through the second filter 1027 and then reflected by the second mirror 1028, and the long-wavelength signal light reflected by the second filter 1027 form an angle 2A between each pair of the long-wavelength reflection end face of the second filter 1027.
[0038] The long-wavelength signal light, after being split, is transmitted upwards to the second polarization beam splitter of the second polarization beam splitter 1024. The P-beam in the long-wavelength signal light is transmitted, while the S-beam is reflected. The P-beam is reflected by the upper surface of the second polarization beam splitter 1024. After passing through the half-wave plate 1023 and the Faraday rotator crystal 1022 respectively, the polarization directions of both the P-beam and the S-beam remain unchanged. The P-beam enters the first polarization beam splitter 1021 and is transmitted by the first polarization beam splitter. The S-beam enters the first polarization beam splitter 1021, is reflected by the lower surface of the first polarization beam splitter 1021, and then reflected by the first polarization beam splitter. The two beams are combined and transmitted to the left end face of the first polarization beam splitter 1021.
[0039] Similarly, the short-wavelength signal light is also transmitted to the left end face of the first polarizing beam splitter 1021;
[0040] Long-wavelength signal light and short-wavelength signal light are emitted from the left end face of the first polarizing beam splitter 1021 at an angle of 2A and coupled to the first collimator 101. The short-wavelength signal light is coupled to Port3-1 of the first collimator 101, and the long-wavelength signal light is coupled to Port3-2 of the first collimator 101, thereby realizing the function of the circulator.
[0041] The specific embodiments of this utility model have been described above. However, those skilled in the art should understand that this is only an example. Those skilled in the art can make various changes or modifications to this embodiment without departing from the principle and essence of this utility model, but all such changes and modifications fall within the protection scope of this utility model.
Claims
1. A low-cost integrated module for a polarization-independent optical circulator and filter, characterized in that: It includes a first collimator, a circulator core, and a second collimator arranged in sequence; The first collimator is a four-fiber collimator, with its four fibers designated as Port1-1, Port1-2, Port3-1, and Port3-2. Port1-1 is used to input short-wavelength signal light, Port1-2 is used to input long-wavelength signal light, Port3-1 is used to output short-wavelength signal light, and Port3-2 is used to output long-wavelength signal light. The first collimator is used to collimate the signal light. The angle between the signal light from Port1-1 and Port1-2 is 2A, the angle between the signal light from Port3-1 and Port3-2 is 2A, the angle between the signal light from Port1-1 and Port3-1 is 2A, and the angle between the signal light from Port1-2 and Port3-2 is 2A. The second collimator is a single-fiber collimator used to collimate the signal light. The fiber of the second collimator is Port2. The second collimator is used to collimate the signal light output from Port1-1 and Port1-2 through the circulator core and couple it to Port2. The circulator core includes a first polarizing beam splitter prism, a half-wave plate, a Faraday rotator crystal, a second polarizing beam splitter prism, a first filter, a first reflector, a second filter, a second reflector, and a magnetic block; the first polarizing beam splitter prism has a trapezoidal cross-section and a first polarizing beam splitting film inside; the second polarizing beam splitter prism has a trapezoidal cross-section and a second polarizing beam splitting film inside. The right end face of the first polarizing beam splitter is attached to the left end face of the Faraday rotator crystal, and the right end face of the Faraday rotator crystal is attached to the left end face of the half-wave plate; the first polarizing beam splitter film is parallel to the lower end face of the first polarizing beam splitter; the left end face of the second polarizing beam splitter film is attached to the right end face of the half-wave plate, and the second polarizing beam splitter film is parallel to the upper end face of the second polarizing beam splitter; the first filter and the first reflector are located to the right of the second polarizing beam splitter, and the second filter and the second reflector are located to the lower side of the second polarizing beam splitter; the first filter and the second filter reflect long-wavelength signal light and transmit short-wavelength signal light; the included angle between the first filter and the first reflector is A; the included angle between the second filter and the second reflector is also A.
2. The integrated module for a low-cost polarization-independent optical circulator and filter according to claim 1, characterized in that: It also includes a base for bonding and fixing the first collimator, the circulator core, and the second collimator.
3. The integrated module for a low-cost polarization-independent optical circulator and filter according to claim 1, characterized in that: The positions of the half-wave plate and the Faraday rotator crystal can be interchanged.
4. The integrated module for a low-cost polarization-independent optical circulator and filter according to claim 1, characterized in that: The value of angle A is less than 5 degrees.