A filter

Abstract

The utility model relates to optical communication device technical field, concretely relates to a filter. The filter includes double fiber subassembly, diffraction element, lens, microcomputer subassembly and light splitting subassembly, diffraction element is located on the incident light path of light input end, is used for diffraction formation different wavelength light beam with the light output of light input end, the lens is located on the emergent light path of diffraction element, to focus the light of multiple different wavelengths that diffraction element output, microcomputer subassembly includes a plurality of reflecting mirrors, a plurality of reflecting mirrors are used for reflecting different wavelength light, light splitting subassembly sets up on the light path between light output end and diffraction element, light splitting subassembly is used for the light that is reflected back by a plurality of reflecting mirrors and carries out light splitting, a part of light is reflected back diffraction element and arrives at the place that reflecting mirror is equipped with detection layer, and reflecting mirror can adjust the reflection angle of itself according to the detection signal of detection layer. The filter can automatically track compensation according to the light attenuation change, guarantees the stable output of channel power.

Description

Technical Field

[0001] This utility model relates to the field of optical communication device technology, and in particular to a filter. Background Technology

[0002] Gain-flattening filters (GFFs) are key optical communication devices primarily used to address gain flatness issues in erbium-doped fiber amplifiers (EDFAs) within wavelength division multiplexing (DWDM) systems. Their working principle involves utilizing a resonant cavity composed of multiple layers of dielectric thin films. This allows light to interfere within the cavity, attenuating specific wavelengths due to destructive interference while allowing other wavelengths to pass through. This "flattening" of the amplifier's gain spectrum ensures balanced transmission of multi-wavelength signals.

[0003] However, in long-distance transmission, the above structure is subject to real-time shifts in the gain spectrum due to fiber nonlinearity, temperature changes, and EDFA aging. Since the attenuation spectrum of such gain-flat filters is fixed, it is impossible to track and compensate for these changes, which can easily lead to channel power imbalance. Utility Model Content

[0004] This invention provides a filter to solve the problem of channel power imbalance caused by the filter's inability to track and compensate for attenuation changes.

[0005] This utility model discloses a filter, comprising:

[0006] A dual-fiber assembly, comprising an optical input end and an optical output end;

[0007] A diffraction element, located in the output light path of the light input end, is used to diffract the light output from the light input end into beams of different wavelengths;

[0008] A lens is located in the output light path of the diffraction element to focus multiple beams of light of different wavelengths output by the diffraction element;

[0009] The microcomputer component includes a plurality of reflective micromirrors, which are respectively located in the outgoing light path of the lens and are used to reflect light of different wavelengths so that multiple beams of light of different wavelengths can be reflected back to the lens, the diffraction element and the dual-fiber component in sequence.

[0010] A beam splitter is disposed in the optical path between the light output end and the diffraction element; the light output end is located in the transmission optical path of the beam splitter, and the diffraction element is located in the reflection optical path of the beam splitter; the beam splitter is used to split the light reflected back by the plurality of the reflective micromirrors, part of the light passes through the beam splitter and is incident on the light output end, and the other part of the light is reflected back to the diffraction element.

[0011] The reflective micromirror is provided with a detection layer. The light beam reflected by the beam splitting component back to the diffraction element is split and then incident on the corresponding detection layer through the lens. The reflective micromirror can adjust its own reflection angle according to the detection signal of the detection layer.

[0012] In one embodiment, the beam splitting component includes a transmission region and a reflection region disposed opposite to each other, the transmission region being located in the emission direction of the light input end, and the reflection region being located in the incident direction of the light output end.

[0013] In one embodiment, the transmissive region is configured as an antireflective film, the reflective region is configured as a tap film, and the antireflective film and the tap film are joined together on opposite sides.

[0014] In one embodiment, the antireflective membrane includes a first edge that is serrated; the tap membrane includes a second edge that is serrated, and the first edge is engaged with the second edge.

[0015] In one embodiment, the distance between the optical input terminal and the optical output terminal is greater than or equal to 125 μm and less than or equal to 133 μm.

[0016] In one embodiment, a collimating lens is further included, which is disposed in the optical path between the dual-fiber assembly and the beam splitter assembly for collimating the light.

[0017] In one embodiment, the diffraction element is a planar grating, the lens is a cylindrical lens, and φ is defined as the diffraction angle range corresponding to the planar grating, f1 is the focal length of the collimating lens, f2 is the focal length of the cylindrical lens, L is the modulation length of the microcomputer component, and W is the modulation width of the microcomputer component; wherein, φ*f2<L; f2\f1<W.

[0018] In one embodiment, W is defined as the mode field diameter of the dual-fiber assembly, f1 as the focal length of the collimating lens, f2 as the focal length of the cylindrical lens, and W1 as the single-drive surface circle width of the reflecting micromirror; wherein, f2\f1*W0<W1.

[0019] In one embodiment, D is defined as the round-trip optical path of the collimating lens, and d is the distance between the dual-fiber assembly and the collimating lens; wherein d > D.

[0020] In one embodiment, the collimating lens is a long focal length spherical lens.

[0021] The beneficial effect of the filter provided in this embodiment of the present invention is that the filter can automatically track and compensate according to the changes in optical attenuation, so that the optical signal strength is always within the range of the reference requirement, and the stable output of channel power is guaranteed.

[0022] Specifically, the light emitted from the optical input end of the dual-fiber assembly sequentially passes through diffraction elements and lenses to the microcomputer assembly. Then, the micromirrors of the microcomputer assembly sequentially reflect light signals of different wavelengths back to the optical output end through lenses and diffraction elements, forming the main optical path. Due to the beam splitter configuration, a portion of the reflected light is output through the optical output end, while the other portion is sequentially reflected back to the diffraction elements and lenses and diffracted to the corresponding detector layers of each micromirror, forming the monitoring optical path. The detector layer can transmit the detected changes in the corresponding wavelength of the light signal to the micromirrors, allowing the micromirrors to adjust their reflection angles to restore the output light signals of different wavelengths to the reference range, achieving self-feedback modulation of the dynamic closed-loop optical path. Therefore, this filter can simultaneously process multi-wavelength deviation signals, ensuring that the output light signals of all wavelengths are adjusted to the reference range, avoiding overcompensation of a single wavelength that leads to power overflow in other wavelengths, achieving balanced steady-state adjustment of the optical signal, and ensuring stable output power of the filter. Attached Figure Description

[0023] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the filter structure provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of the beam splitting component provided in an embodiment of the present invention; wherein, 2a is a front view of the beam splitting component and 2b is a side view of the beam splitting component;

[0026] Figure 3 This is a modulation flowchart of the filter provided in an embodiment of the present invention.

[0027] The labels for the attached figures are as follows:

[0028] 1000, Filter

[0029] 101. Dual-fiber assembly; 1011. Optical input terminal; 1012. Optical output terminal;

[0030] 102. Collimating lens;

[0031] 103, beam splitting component; 1031, transmission region; 1031a, first edge; 1032, reflection region; 1032a, second edge;

[0032] 104. Diffraction element;

[0033] 105. Lens;

[0034] 106. Microcomputer component; 1061. Reflective micromirror; 1061a. Detector layer; 1061b. Reflective modulation mirror. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0036] This utility model embodiment provides a filter 1000, such as Figure 1 - Figure 3 As shown, the filter 1000 includes a dual-fiber assembly 101, a diffraction element 104, a lens 105, a microcomputer assembly 106, and a beam splitter 103. The dual-fiber assembly 101 includes a light input end 1011 and a light output end 1012. The diffraction element 104 is located on the output light path of the light input end 1011 and is used to diffract the light output from the light input end 1011 into beams of different wavelengths. The lens 105 is located on the output light path of the diffraction element 104 to focus the multiple beams of light of different wavelengths output from the diffraction element 104. The microcomputer assembly 106 includes a plurality of reflecting micromirrors 1061, which are respectively located on the output light path of the lens 105 and are used to reflect light of different wavelengths so that multiple beams of light of different wavelengths can be reflected back to the lens 105 and the diffraction element 106 in sequence. 04 and a dual-fiber assembly 101; a beam splitter 103 is disposed in the optical path between the optical output end 1012 and the diffraction element 104; the optical output end 1012 is located in the transmission optical path of the beam splitter 103, and the diffraction element 104 is located in the reflection optical path of the beam splitter 103; the beam splitter 103 is used to split the light reflected back by a plurality of reflective micromirrors 1061, part of the light passes through the beam splitter 103 and is incident on the optical output end 1012, and the other part of the light is reflected back to the diffraction element 104; wherein, the reflective micromirror 1061 is provided with a detector layer 1061a, the light reflected back to the diffraction element 104 by the beam splitter 103 is split and incident on the corresponding detector layer 1061a through the lens 105, and the reflective micromirror 1061 can adjust its own reflection angle according to the detection signal of the detector layer 1061a. This application can solve the problem in the prior art that the filter cannot track and compensate for attenuation changes, resulting in channel power imbalance. The filter 1000 can automatically track and compensate for changes in optical attenuation, ensuring that the optical signal strength is always within the reference range and guaranteeing stable output of channel power.

[0037] Specifically, the light emitted from the optical input terminal 1011 of the dual-fiber assembly 101 (such as...) Figure 2 As shown in P of 2b, the light signals of different wavelengths sequentially pass through diffraction element 104 and lens 105 to the microcomputer component 106. Then, the various reflecting micromirrors 1061 of the microcomputer component 106 reflect the light signals of different wavelengths sequentially through lens 105 and diffraction element 104 back to the light output terminal 1012, forming the main optical path. Due to the arrangement of the beam splitter 103, a portion of the reflected light (such as...) Figure 2 The light (as shown in O of 2b) will be output outward through the light output terminal 1012, and another part of the light (such as...) Figure 2 As shown in Figure 2b (I), the light signals are sequentially reflected back to the diffraction element 104 and lens 105, and then diffracted to the corresponding detector layer 1061a of each reflective micromirror 1061, forming a monitoring optical path. The detector layer 1061a can transmit the detected changes in the corresponding wavelength of the light signal to the reflective micromirror 1061, so that the reflective micromirror 1061 adjusts its reflection angle in real time according to the intensity of the light signal, so that the output light signals of different wavelengths are restored to the range required by the reference, realizing the self-feedback modulation of the dynamic closed-loop optical path. It can be seen that the filter 1000 can process the deviation signals of multiple wavelengths simultaneously, ensuring that the output light signals of all wavelengths are adjusted to the reference range, avoiding the power overflow of other wavelengths due to overcompensation of a single wavelength, realizing the balanced steady-state adjustment of the light signal, and ensuring the stable output power of the filter 1000.

[0038] In this application, the reflective micromirror 1061 further includes a reflective modulation mirror 1061b and a driving processing module. The driving processing module is connected to the reflective modulation mirror 1061b, which is used to reflect light. The driving processing module is electrically connected to the detector layer 1061a. The driving processing module can compare the signal from the detector layer 1061a with the corresponding reference wavelength signal to perform energy calibration on the light signals of different wavelengths, and drive the reflective modulation mirror 1061b to adjust its position to a suitable reflection angle, so that each light signal of the reflected light can be adjusted to be consistent with the preset corresponding reference wavelength signal, thereby realizing self-feedback modulation. Specifically, the reflective micromirror 1061 can be a MEMS micromirror.

[0039] The drive processing module can generate driving force to drive the reflective modulation mirror 1061b to deflect using electrostatic, electromagnetic, piezoelectric, thermal, and motor driving methods. No restrictions are placed on the setting method of the drive processing module here.

[0040] There are many ways to configure the detector layer 1061a of the micromirror 1061. In one embodiment, the detector layer 1061a is a PD detector. Preferably, a smaller PD array detector can be used to improve the consistency and accuracy of the self-feedback modulation. Furthermore, the PD detectors on each micromirror 1061 are of the same model and batch to ensure consistent detection. In another embodiment, the detector layer 1061a is a PD chip. Preferably, a small-sized PD chip is used for the detector layer 1061a, which improves detection accuracy and also increases the detection density per unit area of ​​the micromirror 1061, thereby improving the resolution of the filter 1000.

[0041] In one embodiment, the beam splitter 103 includes a transmission region 1031 and a reflection region 1032 disposed opposite to each other. The transmission region 1031 is located in the emission direction of the light input end 1011, and the reflection region 1032 is located in the incident direction of the light output end 1012. Thus, the transmission region 1031 is disposed between the light input end 1011 and the incident light path of the diffraction element 104. On the one hand, it allows the incident light to be transmitted through the transmission region 1031 to the diffraction element 104. On the other hand, it can effectively block the backlight generated at the diffraction element 104 from returning to the light input end 1011, reducing backlight crosstalk. The setting of the reflection region 1032 ensures that part of the reflected light can be incident to the light output end 1012 for outward output, and the other part can be reflected back to the reflective micromirror 1061, thereby effectively improving the stability and reliability of the filter 1000.

[0042] In a specific embodiment, the transmissive region 1031 is configured as an antireflective film, and the reflective region 1032 is configured as a tap film, with the antireflective film and the tap film joined together on opposite sides. Thus, the antireflective film can reflect a portion of the light back to the detector layer 1061a by precisely controlling the beam splitting ratio. This allows it to cooperate with the microcomputer component 106 to achieve real-time monitoring and feedback without significantly interfering with the main optical path, resulting in higher detection accuracy. Preferably, the reflectivity of the tap film is in the range of 0.8% to 1%.

[0043] It is worth mentioning that the above embodiment sets the antireflection membrane and the Tap membrane as an integrated membrane, which is more conducive to assembly and subsequent maintenance of the filter 1000.

[0044] When light waves pass through the seam between the antireflection film and the tap film, they easily exhibit fan-shaped diffraction. This diffracted light forms spatial interference fringes, resulting in uneven intensity distribution of different wavelengths and causing spectral fluctuations. To address this technical problem, in one embodiment, the antireflection film includes a first edge 1031a, which is serrated; the tap film includes a second edge 1032a, which is also serrated, and the first edge 1031a is engaged with the second edge 1032a. Thus, both the first edge 1031a and the second edge 1032a are serrated. After engagement, the diffracted waves generated by the light waves passing through the serrated structure interfere and cancel each other out, effectively reducing edge diffraction caused by mutual blocking at the joint and minimizing spectral fluctuations due to diffraction.

[0045] Preferably, the sawtooth period of the first edge 1031a and the second edge 1032a can be set to an isosceles structure greater than 10 μm, so that the first edge 1031a and the second edge 1032a can suppress light in different wavelength ranges, thereby further reducing the generation of diffraction effects.

[0046] In one embodiment, the dual-fiber assembly 101 may employ a racetrack-shaped capillary to further reduce the spacing between the input fiber and the output fiber, thereby reducing return loss.

[0047] There are many specific implementations of the optical input terminal 1011 and the optical output terminal 1012. In one embodiment, to meet the loss requirements of long-distance optical paths, the fiber cores of the optical input terminal 1011 and the optical output terminal 1012 can be selected from optical fibers with small cladding diameters; in another embodiment, the fiber cladding of the optical input terminal 1011 and the optical output terminal 1012 can be retrieved by etching. In both cases, the distance between the optical input terminal 1011 and the optical output terminal 1012 can be reduced, thereby avoiding return light loss.

[0048] Optical signals transmitted through optical fibers exist in the form of mode fields, with their energy distributed around the fiber core diameter, forming a certain mode field diameter. When there is a gap between the end faces of the two optical fibers, the light emitted from the input fiber will diverge due to diffraction, resulting in an expansion of the optical field range reaching the end face of the output fiber. If the gap is too small, contact between the fibers may increase light reflection or scattering; if the gap is too large, the diverged optical field will exceed the receiving range of the output fiber, and the unreceived light energy will be lost as a loss. To solve this technical problem, in one embodiment, the distance between the optical input end 1011 and the optical output end 1012 is greater than or equal to 125 μm and less than or equal to 133 μm. With this setting, the optical input end 1011 and the optical output end 1012 are controlled within the optimal gap range to further reduce the loss of long-distance optical transmission paths.

[0049] In one embodiment, the filter 1000 further includes a collimating lens 102, which is disposed in the optical path between the dual-fiber assembly 101 and the beam splitter assembly 103 for collimating the light. Thus, the collimating lens 102 can collimate the passing light, converting divergent light into parallel light, ensuring that the emitted light energy is concentrated within the effective receiving range of subsequent optical path devices, and reducing energy loss.

[0050] In one embodiment, the antireflective coating and the tap film are bonded to the optical path of the collimating lens 102. This reduces the gap space between components, thereby reducing the size of the filter 1000 and facilitating a miniaturized overall structure.

[0051] In one embodiment, the diffraction element 104 is a planar grating, and the lens 105 is a cylindrical lens. φ is defined as the diffraction angle range corresponding to the planar grating, f1 as the focal length of the collimating lens 102, f2 as the focal length of the cylindrical lens, L as the modulation length of the microcomputer component 106, and W as the modulation width of the microcomputer component 106; wherein φ*f2<L; f2\f1<W. Thus, after the collimating lens 102 collimates the incident light into parallel light, the planar grating diffracts light of different wavelengths, generating angular differences; subsequently, the cylindrical lens converges the diffracted light onto the various reflecting micromirrors 1061 of the microcomputer component 106. When φ*f2 < L, the spot positions corresponding to all wavelengths separated by the grating fall within the modulation length range of the microprocessor component 106. This avoids the loss of some wavelengths due to excessive dispersion exceeding the modulation region, thus ensuring that the microprocessor component 106 can finely modulate the wavelengths across the entire band. Furthermore, if f2\f1 < W, the width of the converged spot is limited to the modulation width range of the microprocessor component 106, and the spot size exceeds the driving area of ​​a single reflective micromirror 1061. In this case, a single spot needs to cover multiple reflective micromirrors 1061. Each reflective micromirror 1061 can independently adjust its reflection angle or phase. By coordinating the receiving surface source of the reflective micromirrors 1061 to modulate the spot in different regions, more precise control of the light field is achieved. Combined with the adjustment of full-band coverage, the modulation resolution of the filtered band is ultimately enhanced.

[0052] Light of different wavelengths converges into different spots after passing through a cylindrical lens and falls onto the reflection modulation mirror 1061b of a single reflective micromirror 1061. If light of the same wavelength covers the reflection modulation mirrors 1061b of multiple reflective micromirrors 1061, the modulation of the same spot by different reflective micromirrors 1061 will interfere with each other, affecting modulation accuracy. To solve this technical problem, in one embodiment, W is defined as the mode field diameter of the dual-fiber assembly 101, f1 as the focal length of the collimating lens 102, f2 as the focal length of the cylindrical lens, and W1 as the width of the single driving surface circle of the reflective micromirror 1061; where f2 ≤ f1 * W0 < W1. With this configuration, each converged spot falls completely within the reflection modulation mirror 1061b of a single reflective micromirror 1061. At this time, a single micromirror can independently control the reflection angle or phase of the spot, accurately modulating the corresponding wavelength of the light signal. The collaborative operation of several reflective micromirrors 1061 increases the modulation complexity and further ensures the resolution of the filtered band modulation.

[0053] When light passes through the optical fiber and collimating lens 102, Fresnel reflection occurs, forming reflected light. If the difference between the optical path length of some reflected light and the optical path length of the light at the optical input end 1011 is small, it can cause coherent interference between the reflected light and the main signal light, resulting in light intensity fluctuations or signal distortion. To solve this technical problem, in one embodiment, D is defined as the round-trip optical path length of the collimating lens 102, and d is the distance between the dual-fiber assembly 101 and the collimating lens 102; where d > D. With this configuration, the optical path length of the reflected light significantly exceeds the optical path length of the optical input end 1011, preventing interference between the reflected light and the light at the optical input end 1011. This effectively suppresses light intensity fluctuations or signal distortion, thereby significantly improving the stability of the system's optical signal transmission.

[0054] In one embodiment, the collimating lens 102 is a long focal length spherical lens. Thus, the longer focal length of the long focal length spherical lens increases the beam radius at the lens. A larger beam radius results in a smaller divergence angle after collimation. Therefore, using a long focal length spherical lens can significantly reduce the divergence angle of the collimated beam, making the beam closer to ideal parallel light and reducing energy loss or wavelength separation deviation caused by beam divergence during subsequent beam splitting or modulation.

[0055] Preferably, the collimating lens 102 is an aspherical lens to further reduce coupling loss. In this way, the aspherical lens can effectively correct spherical aberration and improve the wavefront quality of the beam.

[0056] In one embodiment, the filter 1000 further includes a circuit equalizer (not shown) electrically connected to the micromirror 1061. The circuit equalizer can accurately calibrate its modulation differences to different wavelengths, perform equalization feedback and amplification in specific segments, and further improve detection consistency.

[0057] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.

Claims

1. A filter, characterized by, include: A dual-fiber assembly, comprising an optical input end and an optical output end; A diffraction element, located in the output light path of the light input end, is used to diffract the light output from the light input end into beams of different wavelengths; A lens is located in the output light path of the diffraction element to focus multiple beams of light of different wavelengths output by the diffraction element; The microcomputer component includes several reflective micromirrors, all of which are located in the outgoing light path of the lens and are used to reflect light of different wavelengths so that multiple beams of light of different wavelengths can be reflected back to the lens, the diffraction element and the dual-fiber component in sequence. A beam splitter is disposed in the optical path between the light output end and the diffraction element; the light output end is located in the transmission optical path of the beam splitter, and the diffraction element is located in the reflection optical path of the beam splitter; the beam splitter is used to split the light reflected back by the plurality of the reflective micromirrors, part of the light passes through the beam splitter and is incident on the light output end, and the other part of the light is reflected back to the diffraction element. The reflective micromirror is provided with a detection layer. The light beam reflected by the beam splitting component back to the diffraction element is split and then incident on the corresponding detection layer through the lens. The reflective micromirror can adjust its own reflection angle according to the detection signal of the detection layer.

2. The filter of claim 1, wherein, The beam splitter includes a transmission region and a reflection region arranged opposite to each other. The transmission region is located in the emission direction of the light input end, and the reflection region is located in the incident direction of the light output end.

3. The filter of claim 2, wherein, The transmissive region is configured as an antireflective film, and the reflective region is configured as a Tap film. The antireflective film and the Tap film are joined together on opposite sides.

4. The filter of claim 3, wherein, The antireflective membrane includes a first edge, which is serrated; the tap membrane includes a second edge, which is serrated, and the first edge is engaged with the second edge.

5. The filter of claim 1, wherein, The distance between the optical input terminal and the optical output terminal is greater than or equal to 125 μm and less than or equal to 133 μm.

6. The filter according to any one of claims 1-5, characterized in that, It also includes a collimating lens, which is disposed in the optical path between the dual-fiber assembly and the beam splitter assembly, for collimating the light.

7. The filter according to claim 6, characterized in that, The diffraction element is a planar grating, the lens is a cylindrical lens, and φ is defined as the diffraction angle range corresponding to the planar grating, f1 is the focal length of the collimating lens, f2 is the focal length of the cylindrical lens, L is the modulation length of the microcomputer component, and W is the modulation width of the microcomputer component; wherein, φ*f2<L; f2\f1<W.

8. The filter according to claim 7, characterized in that, Define W as the mode field diameter of the dual-fiber assembly, f1 as the focal length of the collimating lens, f2 as the focal length of the cylindrical lens, and W1 as the single-drive surface circle width of the reflecting micromirror; where f2\f1*W0<W1.

9. The filter according to claim 6, characterized in that, Let D be the round-trip optical path of the collimating lens, and d be the distance between the dual-fiber assembly and the collimating lens; where d > D.

10. The filter according to claim 6, characterized in that, The collimating lens is a long focal length spherical lens.

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