A filter based on a tiled grating and an optical communication device

Abstract

The utility model relates to laser communication technical field, especially a filter and optical communication equipment based on spliced grating. The filter based on spliced grating includes: double fiber collimator for providing the light signal of filtering and receiving the light signal of filtering, spliced grating subassembly includes at least two spliced and fixed line number different grating, spliced grating subassembly is located double fiber collimator output the side of light signal of filtering, and the filter surface of grating forms the preset angle with the transmission direction of light signal of filtering, micro - mirror array is located spliced grating subassembly away from the side of double fiber collimator, the light spot of light signal of filtering and the light signal of filtering on spliced grating subassembly is located the splicing line of two adjacent grating. The utility model makes the simple structure of filter, and the cost is lower, and it is more easily realized, and the maintenance cost is also lower.

Description

Technical Field

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

[0002] Conventional planar grating tunable filters, limited by diffraction principles and grating structures, typically exhibit a single Gaussian or quasi-Gaussian distribution in their filtering spectrum, making it difficult to flexibly adapt to filtering requirements in special bands (such as multi-peaked filters). To achieve complex spectral modulation, additional modulation components (such as deformable mirrors or liquid crystal spatial light modulators) are often required, which increases system complexity and cost.

[0003] While high-order arbitrary spectral modulators like WSS (Wavelength Selective Switch) can achieve precise spectral control through multi-level gratings, dynamic phase arrays, or digital micromirror devices, their reliance on sophisticated optical and electronic control modules further increases cost and power consumption. This technological approach, while pursuing flexibility, inevitably brings higher implementation difficulty and maintenance costs. Utility Model Content

[0004] This utility model provides a filter and optical communication device based on spliced ​​gratings to solve the problems of high system complexity, high cost, high implementation difficulty and high maintenance difficulty.

[0005] This utility model discloses a filter based on a spliced ​​grating, comprising:

[0006] A dual-fiber collimator is used to provide the optical signal to be filtered and to receive the filtered optical signal.

[0007] A splicing grating assembly includes at least two spliced ​​gratings with different line counts. The splicing grating assembly is located on the side where the dual-fiber collimator outputs the optical signal to be filtered, and the filtering surface of the grating forms a preset angle with the transmission direction of the optical signal to be filtered.

[0008] The micromirror array is located on the side of the splicing grating assembly away from the dual-fiber collimator;

[0009] The light spots of the optical signal to be filtered and the filtered optical signal on the splicing grating assembly are located on the splicing line of two adjacent gratings.

[0010] Optionally, the filter based on the spliced ​​grating further includes:

[0011] A waveplate is located between the splicing grating assembly and the micromirror array.

[0012] Optionally, the dual-fiber collimator includes:

[0013] An input optical fiber is used to output the optical signal to be filtered;

[0014] An output optical fiber is used to receive the filtered optical signal;

[0015] A capillary tube is used to fix the input optical fiber and the output optical fiber, and is wrapped around the periphery of the input optical fiber and the output optical fiber;

[0016] A collimating lens is located at the output end of the input optical fiber and the input end of the output optical fiber.

[0017] Optionally, the collimating lens is a spherical lens with a radius of curvature of 1.5mm to 2mm.

[0018] Optionally, the inner diameter of the capillary is 133µm.

[0019] Optionally, the direction of the optical axis connection between the input optical fiber and the output optical fiber is parallel to the splicing direction of the grating.

[0020] Optionally, the difference in the number of lines of adjacent gratings shall not exceed 20.

[0021] Optionally, the micromirror array is located at the waist of the light signal emitted from the waveplate.

[0022] Optionally, adjacent gratings are bonded together with light-absorbing adhesive.

[0023] This utility model also discloses an optical communication device, including the filter based on spliced ​​grating as described above.

[0024] The beneficial effects of the filter and optical communication device based on spliced ​​gratings provided by this utility model embodiment are as follows: at least two gratings with different line counts are spliced ​​together, and the filtering surface of the grating forms a preset angle with the transmission direction of the optical signal to be filtered. When the optical signal to be filtered by the dual-fiber collimator is incident on the splicing line of two adjacent gratings, it is diffracted and split by the two gratings respectively. Since the line counts of the gratings are different, the diffraction and splitting capabilities are different. By adjusting the deflection angle of the micromirrors in the micromirror array, the optical signals with different wavelengths split by different gratings can be reflected and converged into a filtered optical signal, which is then emitted through the dual-fiber collimator. The dual-grating splicing scheme completes wavelength separation and synthesis in a single plane. Combined with the use of a micromirror array to achieve wavelength selection, the filter structure is simple, the cost is low, it is easier to implement, and the maintenance cost is also lower. Attached Figure Description

[0025] 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:

[0026] Figure 1This is a schematic diagram of an embodiment of the filter based on spliced ​​grating provided by this utility model;

[0027] Figure 2 This is a cross-sectional schematic diagram of the splicing grating assembly provided by the present invention.

[0028] The labels for the attached figures are as follows:

[0029] 10. Filter based on spliced ​​grating; 11. Dual-fiber collimator; 111. Input fiber; 112. Output fiber; 113. Capillary; 114. Collimating lens; 12. Spliced ​​grating assembly; 121. Grating; 13. Micromirror array; 14. Waveplate. Detailed Implementation

[0030] 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.

[0031] Please see Figure 1 , Figure 1 This is a schematic diagram of an embodiment of the spliced ​​grating-based filter provided by this utility model. The spliced ​​grating-based filter 10 includes a dual-fiber collimator 11, a spliced ​​grating assembly 12, and a micromirror array 13.

[0032] The dual-fiber collimator 11 includes two optical fibers, one as an output fiber 112 and the other as an input fiber 111. The output fiber 112 is used to transmit the optical signal to be filtered, so that the dual-fiber collimator 11 can output the optical signal to be filtered. The input fiber 111 is used to transmit the filtered optical signal, so that the dual-fiber collimator 11 can receive the filtered optical signal. The input fiber 111 and the output fiber 112 can be SM28e fiber or other types of fiber.

[0033] The splicing grating assembly 12 is located on one side of the output optical signal to be filtered from the dual-fiber collimator 11, allowing the optical signal to pass through the splicing grating assembly 12 for filtering. The splicing grating assembly 12 includes at least two sequentially spliced ​​gratings 121, with different line counts. Gratings 121 with different line counts have different periods, thus possessing different wavelength selective modulation capabilities. The filtering surface of the grating 121 forms a preset angle with the transmission direction of the optical signal to be filtered. The filtering surface of the grating 121 is the side with grooves etched at preset intervals. By reasonably setting the interval of the grooves, narrowband transmission or suppression of specific wavelengths can be achieved. When the optical signal to be filtered strikes the filtering surface of the grating 121, it is refracted at the filtering surface and transmitted to the other side of the grating 121, where it is refracted again and diffracted, resulting in a wavelength-modulated signal.

[0034] The micromirror array 13 is located on the side of the splicing grating assembly 12 away from the dual-fiber collimator 11. It is used to reflect at least a portion of the optical signal emitted from the splicing grating assembly 12 back to the splicing grating assembly 12.

[0035] In one embodiment, the filter 10 based on the spliced ​​grating further includes a waveplate 14 located between the spliced ​​grating assembly 12 and the micromirror array 13. This allows the light signal emitted from the spliced ​​grating assembly 12 to have its polarization characteristics altered by the waveplate 14, and the light signal reflected back by the micromirrors in the micromirror array 13 to have its polarization characteristics altered again by the waveplate 14. The waveplate 14 can be either a half-waveplate or a quarter-waveplate, which can be selected by the user according to actual needs.

[0036] Specifically, after the dual-fiber collimator 11 outputs the optical signal to be filtered, it is emitted onto the splicing grating assembly 12. Since the splicing grating assembly 12 consists of at least two sequentially spliced ​​gratings 121, the position of the optical signal to be filtered on the surface of the splicing grating assembly 12 can be controlled by adjusting the position of the splicing grating assembly 12 relative to the dual-fiber collimator 11. The spot of the optical signal to be filtered can be located on the filtering surface of one grating 121, or the spot of the optical signal to be filtered can be located on the splicing line of two adjacent gratings 121.

[0037] Taking the example of the light spot of the optical signal to be filtered located on the splicing line of two adjacent gratings 121, the gratings 121 with different scribe line densities (e.g., high-density grating A for short wavelengths and low-density grating B for long wavelengths) have different wavelength sensitivities. When the light spot is centered: short-wavelength light mainly falls in the high-density area (strong dispersion, high resolution), while long-wavelength light mainly falls in the low-density area (weak dispersion, wide coverage), avoiding the dominance of a single grating and achieving efficient utilization across the entire wavelength band.

[0038] The diffraction characteristics of grating 121 are determined by the grating equations. Assume the grating equations for the two gratings 121 are as follows:

[0039]

[0040]

[0041] in, , These correspond to the line pair widths of the two gratings 121, , The incident angles and diffraction angles of the two gratings 121 are respectively. Since the incident surfaces of the two gratings 121 are located on the same plane, the incident angles of the two gratings 121 are the same. And since the difference in the fixed line count of adjacent gratings in this application does not exceed 20, the diffraction angles can be considered to be approximately the same. , These correspond to the wavefront filtering wavelengths of the two gratings 121, respectively.

[0042] Thus, when the light spot of the optical signal to be filtered is located on the splicing line of two adjacent gratings 121, a portion of the wavelength of the optical signal to be filtered will be... The optical signal can be filtered by the grating 121 and emitted from the splicing grating assembly 12, and then emitted to the micromirror array 13. Another portion of the optical signal to be filtered contains wavelengths... The optical signal can be filtered by the grating 121 and emitted from the splicing grating assembly 12, and then onto the micromirror array 13. And because of the wavelength... optical signals and wavelengths The diffraction angles of the two light signals are approximately equal, therefore it can be assumed that the transmission directions of the two light signals are very close. The wavelength can be adjusted by appropriately setting the deflection direction of the micromirrors in the micromirror array 13. optical signals and wavelengths The optical signal can return along the original outgoing optical path. Please refer to [reference needed]. Figure 2 , Figure 2 This is a cross-sectional schematic diagram of the splicing grating assembly provided by the present invention.

[0043] Specifically, after being filtered by two gratings 121, the optical signal to be filtered is transformed into multiple parallel or nearly parallel beams, which are then emitted. After the polarization state is changed by waveplate 14, a micromirror array 13 is set up. By appropriately setting the deflection angle of the micromirrors in the micromirror array 13, only beams of a specific wavelength are reflected back precisely along their original optical path after being reflected by the micromirror array 13. The micromirror array 13 selectively reflects incident beams of a specific direction (i.e., a specific wavelength) back to the desired direction by changing its tilt angle. This "desired direction" is the direction that allows the beam to be precisely coupled back to the output fiber 112 of the dual-fiber collimator 11 after passing through waveplate 14 and the splicing grating assembly 12. When the micromirror array 13 rotates to a specific angle, it only reflects the target wavelength... and The optical signal is reflected back to the "correct" path. Light of other wavelengths is reflected in other directions and cannot be effectively coupled back to the output, thus achieving filtering.

[0044] In one implementation scenario, the dual-fiber collimator 11 includes: an input fiber 111, an output fiber 112, a capillary tube 113, and a collimating lens 114. The input fiber 111 outputs the optical signal to be filtered; the output fiber 112 receives the filtered optical signal; the capillary tube 113 fixes the input fiber 111 and the output fiber 112, wrapping around them; the collimating lens 114 is located at the output end of the input fiber 111 and the input end of the output fiber 112, and is used to collimate the optical signal to be filtered and the filtered optical signal. The reflected optical signal (target wavelength) and The optical signal (the light signal) shines again onto the splicing grating assembly 12. Since the optical path is ideally reversible (and the angle setting of the micromirror array ensures the reversibility of the optical path for the target wavelength), the target wavelength... and After being diffracted by grating 121, the optical signal is combined (the different gratings act as the reverse process) and converges back to the direction of incidence, becoming a filtered optical signal. The converged filtered optical signal is focused by collimating lens 114 and efficiently coupled into the output fiber of dual-fiber collimator 11. Based on the spliced ​​grating filter 10, a filtered optical signal with two wavelengths is output.

[0045] Waveplate 14 works in conjunction with micromirror array 13. For example, a quarter-waveplate can convert linearly polarized light into circularly polarized light (incidentally incident on the micromirror array), and then convert the circularly polarized light reflected back from the micromirror array back into linearly polarized light (but with the polarization direction rotated by 90 degrees). This is important for using polarization-independent devices or achieving specific polarization-dependent modulation. It does not directly perform filtering itself, but it creates conditions for efficient, polarization-independent (or controllable) reflection of the micromirror array 13. This allows the diffraction efficiency difference of the grating 121 for the two polarization states to be averaged, eliminating loss fluctuations caused by polarization sensitivity.

[0046] Specifically, an arbitrary polarization state light signal becomes circularly polarized light (left-handed or right-handed) after passing through a quarter-wave plate. The circularly polarized light is reflected by the micromirror array 13 and its rotation direction is reversed but its orthogonality is maintained. When it passes through the wave plate 14 in the opposite direction, it is converted into orthogonal linearly polarized light, which is perpendicular to the polarization state of the incident light, thus avoiding interference with the input light and ensuring the reversibility of the optical path and low insertion loss.

[0047] In one implementation scenario, the collimating lens 114 is a spherical lens with a radius of curvature of 1.5mm to 2mm. The spherical design with a radius of curvature of 1.5mm to 2mm represents an optimized balance between optical performance and mechanical integration: the short focal length (approximately 3.3mm) corresponding to this curvature range can efficiently collimate a 10.4μm spot from a single-mode fiber into a 0.5mm parallel beam (divergence angle <0.05°), while simultaneously controlling spherical aberration within λ / 10 through hyperboloid correction, ensuring grating coupling loss <0.3dB; the small radius of curvature also meets the 5mm packaging thickness limit, compressing the distance from the fiber end face to the grating to 6mm, and achieving a thermal drift as low as 10⁻ 5 / °C, its collimated spot size of 1mm is precisely matched with the grating coherence length of 0.8mm, avoiding multi-wavelength interference ripple, and finally achieving wavelength accuracy of ±0.02nm and environmental stability of -40~85℃. Actual measurements show that deviation from this range will cause the insertion loss to increase sharply by more than 2dB.

[0048] In one implementation scenario, the capillary 113 has an inner diameter of 133µm. This 133µm inner diameter forms a uniform 8µm gap with the standard single-mode fiber (bare fiber diameter 125µm), ensuring smooth fiber insertion (avoiding stress damage) and achieving a positioning accuracy of ±0.5µm after UV adhesive filling and curing. This ensures that the axial misalignment angle of the input / output fibers is <0.1°, guaranteeing a grating coupling efficiency >95%. The capillary (typically made of quartz) and the optical fiber have matching coefficients of thermal expansion (α≈0.55×10⁻). 6 Within a temperature range of -40 to 85°C, the 133µm design ensures that the core shift caused by thermal stress is <0.1µm (corresponding to wavelength drift <0.02nm), meeting the Telcordia GR-1209 standard.

[0049] In one embodiment, the direction of the dual-fiber connection of the dual-fiber collimator 11 (i.e., the direction of the connection between the axes of the input fiber 111 and the output fiber 112) is set to be strictly parallel to the direction of the splice seam of the grating 121 (i.e., the direction of the physical boundary line between the two gratings 121). If the dual-fiber connection is parallel to the splice seam (i.e., perpendicular to the direction of the grating scribe line), then the direction of movement of the incident light spot (along the dual-fiber connection) is orthogonal to the wavelength spatial separation direction (along the direction of diffraction angle change). Wavelength separation only occurs in a single-axis direction (such as the horizontal axis) and is decoupled from the direction of light spot position adjustment (such as the vertical axis). When adjusting the light spot position (moving in the Y direction), the wavelength separation direction (X direction) will not be disturbed, thus avoiding spectral distortion.

[0050] In one embodiment, precisely aligning the micromirror array 13 with the beam waist of the light emitted from the waveplate 14 is a key design feature for achieving high-performance filtering. The beam waist has the smallest spot diameter and the most concentrated energy, resulting in micromirror reflection loss of less than 0.2 dB. At the same time, the beam collimation is optimal at this position, which can improve the micromirror tilt angle resolution to 0.001 nm / mrad and ensure wavelength tuning accuracy of ±0.005 nm. Furthermore, the beam waist serves as the center of symmetry for the optical path, ensuring mode matching between forward beam splitting and reverse beam combining (loss <0.1 dB) and controlling the passband ripple to within 0.2 dB by eliminating wavefront distortion.

[0051] In one implementation scenario, adjacent gratings 121 are bonded together using light-absorbing adhesive. This adhesive (typically containing carbon black or special dyes) can absorb over 99.5% of stray light (wavelength range covering 1250-1650nm), reducing the backscattering loss at the grating seam from -25dB with conventional adhesives to below -50dB. This "optical blackening" treatment effectively suppresses passband floor noise caused by multiple reflections of diffracted light at the seam.

[0052] As described above, in this embodiment, at least two gratings with different line counts are spliced ​​together, and the filtering surface of the grating forms a preset angle with the transmission direction of the optical signal to be filtered. When the optical signal to be filtered by the dual-fiber collimator is incident on the splicing line of two adjacent gratings, it is diffracted and split by the two gratings respectively. Since the gratings have different line counts, their diffraction and splitting capabilities are different. By adjusting the deflection angle of the micromirrors in the micromirror array, the optical signals with different wavelengths split by different gratings can be reflected and converged into a filtered optical signal, which is then emitted through the dual-fiber collimator. The dual-grating splicing scheme completes wavelength separation and synthesis in a single plane. Combined with the use of a micromirror array to achieve wavelength selection, the filter structure is simple, the cost is low, it is easier to implement, and the maintenance cost is also lower.

[0053] This invention also provides an optical communication device, including the above-described filter based on a spliced ​​grating.

[0054] 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 based on a spliced ​​grating, characterized in that, include: A dual-fiber collimator is used to provide the optical signal to be filtered and to receive the filtered optical signal. A splicing grating assembly includes at least two spliced ​​gratings with different line counts. The splicing grating assembly is located on the side where the dual-fiber collimator outputs the optical signal to be filtered, and the filtering surface of the grating forms a preset angle with the transmission direction of the optical signal to be filtered. The micromirror array is located on the side of the splicing grating assembly away from the dual-fiber collimator; The light spots of the optical signal to be filtered and the filtered optical signal on the splicing grating assembly are located on the splicing line of two adjacent gratings.

2. The filter based on spliced ​​gratings according to claim 1, characterized in that, The grating-based filter also includes: A waveplate is located between the splicing grating assembly and the micromirror array.

3. The filter based on spliced ​​gratings according to claim 1, characterized in that, The dual-fiber collimator includes: An input optical fiber is used to output the optical signal to be filtered; An output optical fiber is used to receive the filtered optical signal; A capillary tube is used to fix the input optical fiber and the output optical fiber, and is wrapped around the periphery of the input optical fiber and the output optical fiber; A collimating lens is located at the output end of the input optical fiber and the input end of the output optical fiber.

4. The filter based on spliced ​​gratings according to claim 3, characterized in that, The collimating lens is a spherical lens with a radius of curvature of 1.5mm to 2mm.

5. The filter based on spliced ​​gratings according to claim 3, characterized in that, The inner diameter of the capillary is 133µm.

6. The filter based on spliced ​​gratings according to claim 3, characterized in that, The direction of the line connecting the optical axes of the input optical fiber and the output optical fiber is parallel to the splicing direction of the grating.

7. The filter based on spliced ​​gratings according to claim 1, characterized in that, The difference in the number of lines between adjacent gratings does not exceed 20.

8. The filter based on spliced ​​gratings according to claim 1, characterized in that, The micromirror array is located at the waist of the light signal emitted from the waveplate.

9. The filter based on spliced ​​gratings according to claim 1, characterized in that, The adjacent gratings are bonded together with light-absorbing adhesive.

10. An optical communication device, characterized in that, Includes the grating-based filter as described in any one of claims 1-9.

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