Low crosstalk high adaptability optical fiber array and preparation method

Abstract

The application relates to the technical field of optical fiber communication, in particular to a low-crosstalk high-adaptability optical fiber array and a preparation method thereof, which comprises an integrated composite substrate. The integrated composite substrate is a layered composite structure comprising a base layer, an optical absorption intermediate layer and a surface strengthening layer, N groups of parallel distributed straight V grooves are arranged on the upper surface and the lower surface of the substrate, the straight V grooves on the upper surface and the straight V grooves on the lower surface are arranged in the same direction and the projection areas are completely dislocated and do not overlap. A low-crosstalk high-adaptability optical fiber array preparation method comprises substrate preparation, optical fiber assembly preparation, encapsulation and curing, end face processing, antireflection film deposition and assembly installation. The application can realize the core advantages of high coupling efficiency, low crosstalk, wide temperature stability and multi-scene adaptation through the dislocated straight V grooves of the integrated composite substrate, the multi-dimensional crosstalk suppression structure, the precise temperature compensation and the flexible parameter design, and can meet the high-end application requirements of high-speed optical communication and large-scale sensing.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of optical fiber communication, in particular to a low-crosstalk high-adaptability optical fiber array and a preparation method. BACKGROUND

[0002] With the rapid development of global digital economy, emerging technologies such as 5G communication, cloud computing, big data and artificial intelligence have put unprecedented requirements on the rate, capacity and reliability of information transmission. In the field of optical fiber sensing, large-scale distributed sensing networks such as structural health monitoring, perimeter security and oil and gas pipeline monitoring need to realize the parallel acquisition and transmission of multi-channel signals at the same time, which puts strict requirements on the number of channels, crosstalk suppression ability and environmental adaptability of optical fiber arrays. As the core coupling component between optical modules and optical fiber links, sensing networks and detection units, the performance of the optical fiber array directly determines the transmission quality and reliability of the entire optoelectronic system. An ideal optical fiber array should have the following core performances: ① high coupling efficiency, reducing optical signal loss; ② low channel crosstalk, avoiding signal interference between different channels; ③ high integration, realizing the integration of multi-channel transceiver functions; ④ high adaptability, compatible with different types of optical chips, optical modules and sensing units; ⑤ wide temperature stability, maintaining stable performance in extreme environments.

[0003] Through retrieval, CN120762165B discloses an optical fiber array, which comprises a fixed part combined by a substrate and a cover plate, and a plurality of optical fibers arranged in the V-shaped grooves in the fixed part. The optical port surface and the tail fiber surface in the fixed part are parallel to each other, the two side surfaces adjacent to the optical port surface or the tail fiber surface in the fixed part are parallel to each other, the included angle between one of the two side surfaces and the optical port surface is A, the included angle between the other side surface and the optical port surface is B, A is 82°±0.5°, and A+B=180°. The processing method comprises the following steps: assembling the optical fiber with the cut-shaped substrate and cover plate; and sequentially performing fine grinding and polishing on the optical port surface of the fixed part.

[0004] In view of the above related art, the inventors have found that the prior art has the following defects: In the prior art, the 800G DR8 silicon optical module usually adopts a double-array scheme, that is, an independent transmitting end (TX) fiber array and an independent receiving end (RX) fiber array are respectively arranged. The two arrays need to be coupled with optical chips respectively, which not only leads to complicated coupling steps, extremely high alignment accuracy, low production efficiency, and installation errors that easily cause signal loss. Some integrated fiber arrays adopt a "bent V-groove" design, which arranges the TX fiber and the RX fiber on the same side of the same substrate, and realizes the upper and lower layer layout through fiber bending. However, the fiber bending radius is often less than the minimum bending radius, which increases the additional loss of optical signals, and the processing precision of the bent V-groove is difficult to control, which further affects the coupling efficiency. At the same time, the existing crosstalk suppression means is single, and the substrate material is usually ordinary borosilicate glass or a silicon wafer, which has weak absorption capacity for scattered light, and the scattered light of adjacent channels easily interferes with each other. The fiber end face is mostly a vertical lapping surface, and the reflectivity of the optical signal at the end face is as high as more than 4%, and the reflected light not only causes return loss, but also scatters through the substrate to the adjacent channel, aggravating crosstalk. SUMMARY

[0005] In order to overcome the deficiencies of the prior art, the present application provides a low-crosstalk high-adaptability optical fiber array and a preparation method.

[0006] The application provides a low-crosstalk high-adaptability optical fiber array, which adopts the technical scheme as follows: comprising an integrated composite substrate, an array optical fiber assembly, a glass cover plate, a packaging adhesive, a transmittance reflection suppression structure and a temperature compensation module, the integrated composite substrate is a layered composite structure, comprising a base layer, an optical absorption intermediate layer and a surface strengthening layer, N groups of parallel distributed straight V grooves are arranged on the upper surface and the lower surface of the substrate, the straight V grooves on the upper surface and the straight V grooves on the lower surface are arranged in the same direction and the projection areas are completely dislocated and do not overlap, the number of straight V grooves in each group is 8-16, the center distance between adjacent straight V grooves is 0.25 mm, 0.5 mm or 1.0 mm; the array optical fiber assembly comprises a transmitting end (TX) optical fiber group and a receiving end (RX) optical fiber group, the number of optical fibers in the TX optical fiber group and the RX optical fiber group is 8-16, and the optical fibers are respectively accommodated in the straight V grooves on the lower surface and the upper surface of the substrate, the bare fiber segments of the optical fibers are arranged without bending, and the end faces are coplanar with the end faces of the substrate; the glass cover plate is divided into an upper cover plate and a lower cover plate, and is respectively correspondingly pressed and combined above the straight V grooves on the upper surface and the straight V grooves on the lower surface, and is fixedly connected with the integrated composite substrate through the packaging adhesive; the transmittance reflection suppression structure comprises an inclined grinding surface of the end face of the optical fiber and a multilayer transmittance film deposited on the surface, the end face inclination angle is 8-12°, and the transmittance film reflectivity is ≤0.2%; the temperature compensation module is embedded in the side groove of the integrated composite substrate and is in thermal coupling with the substrate; the overall optical absorption rate of the integrated composite substrate is 30-45 dB, the optical absorption coefficient of the optical absorption intermediate layer is 10-15 dB / mm, the overall refractive index of the substrate is 1.48-1.58, and the thermal expansion coefficient is 2.0*10 -6 -2.8*10 -6 -3 / K. The upper and lower surface straight V grooves of the integrated composite substrate are completely dislocated and do not overlap in projection, and the built-in optical absorption intermediate layer of the substrate can effectively block the light leakage between the transmitting end (TX) and the receiving end (RX) optical fiber groups, and avoid signal crosstalk; the overall optical absorption rate of the substrate reaches 30-45 dB, further absorbing stray light, and improving the purity of signal transmission. The bare fiber segments of the optical fibers are arranged without bending, reducing the scattered light generated by the bending of the optical fibers, and reducing the crosstalk risk between adjacent optical fibers.

[0007] Optionally, the base layer of the integrated composite substrate is made of borosilicate glass or quartz glass, and the thickness is 2-4 mm; the optical absorption intermediate layer is made of light attenuation glass doped with transition metal oxide, the thickness is 0.5-1.5 mm, the transition metal oxide is one or more of Fe2O3, CoO and NiO, and the total doping amount is 5-10 wt%; the surface strengthening layer is a SiO2-TiO2 composite coating prepared by a sol-gel method, and the thickness is 50-100 nm, and the microhardness is ≥800 HV.

[0008] Optionally, the TX fiber group and the RX fiber group have a spacing of 1.0 mm ± 0.1 mm in the height direction and a center spacing of 2.5 mm ± 0.2 mm in the horizontal direction, and the fiber is a single-mode fiber or a multi-mode fiber, the single-mode fiber has a core diameter of 9 μm, the multi-mode fiber has a core diameter of 50 or 62.5 μm, a cladding diameter of 125 μm, and a coating diameter of 250 μm.

[0009] Optionally, the straight V-groove has a groove angle of 90° ± 2°, a groove depth of 62.5-125 μm, and a groove wall roughness Ra ≤ 0.005 μm, and the length of the straight V-groove is 8-15 mm, and the width of the reserved area of the substrate between the two groups of straight V-grooves is 2-5 mm. The base layer of the integrated composite substrate is made of borosilicate glass or quartz glass, matched with a specific doping amount of transition metal oxide light attenuation glass as an optical absorption intermediate layer, and a high-hardness SiO2-TiO2 composite coating surface reinforcement layer, which not only guarantees the optical absorption performance of the substrate to reduce crosstalk, but also enhances the wear resistance and impact resistance of the substrate, prolonging the overall service life; the precise spacing design of the TX and RX fiber groups in the height and horizontal directions, combined with the flexible selection of single-mode and multi-mode fibers, can meet the docking needs of different types of optical transmission systems, and improve the adaptation range of the product; the precise groove angle, groove depth, roughness, and length parameter design of the straight V-groove can achieve high-precision positioning and stress-free fixing of the fiber, ensure that the bare fiber section is arranged without bending, avoid additional loss caused by fiber deviation or deformation, and further optimize the stability and reliability of signal transmission.

[0010] Optionally, the anti-reflection film is a three-layer dielectric film structure, and from the fiber end face outward, it is sequentially a SiO2 transition layer, a TiO2 high-refractive layer, and a SiO2 low-refractive surface layer, the thicknesses of the respective film layers are 1 / 8, 1 / 4, and 1 / 4 of the transmission wavelength, the transmission wavelength is adapted to 850 nm, 1310 nm, 1550 nm, or 1625 nm, and the anti-reflection film has a rubbing resistance of ≥ 500 times (test conditions: load of 500 g).

[0011] Optionally, the packaging adhesive is a low-refractive modified epoxy resin with a refractive index of 1.42-1.46 and a light transmittance of ≥ 98.5% (test conditions: 200-1600 nm wavelength band), 2-5 wt% of nano-scale light-absorbing particles with a particle diameter of 50-100 nm are added to the adhesive, the light-absorbing particles are carbon black, titanium black, or oxides doped with rare earth elements, the curing conditions of the adhesive are 80°C / 2h + 120°C / 1h, the shear strength after curing is ≥ 15 MPa, and the water absorption is ≤ 0.1%.

[0012] Optionally, the temperature compensation module includes a metal compensation sheet, a heat-conducting silica gel, and a heat-insulating shell, the metal compensation sheet is made of invar steel or titanium alloy, has a thickness of 1-2 mm, and a thermal expansion coefficient of 1.0 × 10 -61.5x10 -6 The thermal conductivity of the high-thermal-conductivity silica gel is greater than or equal to 1.5 W / (m·K), and the heat insulation shell is made of polyimide material with a thickness of 0.5-1 mm.

[0013] Optionally, the straight V-shaped grooves on the upper surface of the substrate can be divided into 2-4 independent groups, the number of straight V-shaped grooves in each group is 4-8, the spacing between groups is 0.5-1.0 mm, and the center lines of the straight V-shaped grooves in each group are parallel, which is suitable for multi-chip parallel coupling requirements.

[0014] Optionally, the fiber end face is subjected to fine grinding and polishing treatment, the roughness Ra is less than or equal to 0.008 μm, the end face perpendicularity is less than or equal to 0.1°, and the coplanarity of all fiber end faces is less than or equal to 0.01 mm; further comprising a dustproof protection assembly, the dustproof protection assembly comprises an end face protection film and a metal dustproof cover, the end face protection film is made of PET material with a light transmittance greater than or equal to 99%, the metal dustproof cover is connected with the integrated composite substrate through a buckle structure, and the dustproof level reaches IP54. The precise film thickness design of the three-layer medium antireflection film is suitable for multi-band transmission requirements, and has low reflectivity and high wear resistance, which can effectively reduce the optical signal loss and prolong the service life of the end face; the low-refractive-index modified epoxy resin packaging adhesive adds nano-level light-absorbing particles, which not only ensures high light transmittance and stable bonding strength, but also absorbs stray light to reduce crosstalk, and the low water absorption rate improves the environmental performance of the adhesive; the temperature compensation module made of invar or titanium alloy material combined with high-thermal-conductivity silica gel can accurately offset the thermal deformation of the substrate, and improve the working stability of the fiber array in a wide temperature environment; the grouping design of the straight V-shaped grooves of the substrate can adapt to the multi-chip parallel coupling requirements, and expand the application scenarios of the product; the fine grinding and polishing treatment of the fiber end face ensures high coplanarity and perpendicularity, and the PET material protection film and IP54 level metal dustproof cover can effectively protect the end face from pollution and damage, and further improve the transmission stability and service life of the fiber array.

[0015] A low-crosstalk high-adaptability fiber array preparation method, comprising the following steps:

[0016] S1. Substrate preparation: borosilicate glass substrate and light attenuation glass blank are selected, and the base layer and light-absorbing intermediate layer of the composite substrate are prepared by high-temperature bonding process; SiO2-TiO2 sol is coated on the upper and lower surfaces of the composite substrate by sol-gel method, and then dried at 150℃ and sintered at 500℃ for 1h to form a surface strengthening layer; the straight V-shaped grooves on the upper and lower surfaces are processed by a precision diamond cutting machine, the cutting speed is 5 mm / s, and the cutting depth control precision is ±1 μm; the substrate is fine ground and polished to a surface flatness of ≤0.003 mm, and grooves are processed on the side of the substrate;

[0017] S2. Fiber assembly preparation: Select 16 single-mode optical fibers, divide them into a transmitting (TX) fiber group and a receiving (RX) fiber group, each group has 8 fibers, and arrange them in order through a fiber array sorting machine; remove the coating layer at one end of the fiber to form a bare fiber segment, and polish the transition area between the bare fiber segment and the coating layer into a circular arc structure; accommodate the two groups of fibers in the straight V-grooves on the upper and lower surfaces of the substrate, adjust the fibers so that the end faces are flush and coplanar with the end face of the substrate, and fix them with temporary fixing glue;

[0018] S3. Encapsulation and curing: inject encapsulation adhesive into the straight V-grooves through an automatic dispensing device, the injection amount is 92% of the volume of the straight V-groove; cover the glass cover plate and apply a uniform pressure of 0.8 N to make the optical fibers tightly fit the straight V-grooves; after curing at 80℃ / 2h+120℃ / 1h, remove the temporary fixing glue;

[0019] S4. End face processing: fix the encapsulated fiber array on an angle grinder, and use 15μm and 3μm diamond grinding wheels to perform coarse grinding and fine grinding at an inclination angle of 9°; polish the end face with 0.1μm cerium oxide polishing liquid until the end face roughness Ra≤0.008μm; clean the end face and dry it;

[0020] S5. Antireflection film deposition: place the fiber array in a vacuum coating machine, evacuate to 5×10 -4 Pa; deposit a SiO2 transition layer, a TiO2 high refractive index layer, and a SiO2 low refractive index surface layer in turn according to the designed thickness, and control the deposition rate to be 0.5nm / s; after coating, perform annealing treatment at 200℃ for 1h;

[0021] S6. Assembly installation: apply thermal conductive silicone glue in the grooves on the side edges of the substrate, embed the metal compensation sheet and compactly fix it; install the heat insulation shell, paste the end face protection film, and assemble the metal dustproof cover.

[0022] In summary, the present application has the following beneficial technical effects:

[0023] 1. The present application projects the straight V-grooves on the upper and lower surfaces of the integrated composite substrate completely out of position, embeds a light-absorbing intermediate layer with high absorption coefficient, and cooperates with nano light-absorbing particles in the encapsulation adhesive to block the light leakage between the TX and RX fiber groups in multiple dimensions; the 8-12° inclined grinding of the fiber end face and the design of the three-layer antireflection film reduce the end face reflection stray light and reduce the channel crosstalk.

[0024] 2. The present application cooperates with the high-hardness surface strengthening layer through the layered composite structure of the substrate, the shear strength of the encapsulation adhesive after curing is ≥15MPa, and the water absorption rate is ≤0.1%; the temperature compensation module is thermally coupled with the substrate to offset the deformation in a wide temperature environment, and cooperates with the IP54 level dustproof protection assembly to ensure the accurate positioning of the optical fiber and the end face is not damaged, and the performance is stable in extreme environments.

[0025] 3. This invention achieves stress-free optical fiber fixation through precision machining of straight V-grooves (groove wall roughness Ra≤0.005μm), and reduces additional loss by arranging bare fiber segments without bending; the high coplanarity of the fiber end face and the anti-reflection coating design improve coupling efficiency, resulting in low optical signal transmission loss and high purity, ensuring the stability and long-term effectiveness of multi-channel parallel transmission. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure in an embodiment of this application;

[0027] Figure 2 This is a top-view schematic diagram of the internal structure in an embodiment of this application;

[0028] Figure 3 This is a schematic diagram of the temperature compensation module in an embodiment of this application;

[0029] Figure 4 This is another perspective schematic diagram of the internal structure in the embodiments of this application;

[0030] Figure 5 yes Figure 4 Enlarged structural diagram of section A in the middle;

[0031] Figure 6 This is a schematic diagram of the internal front view structure in an embodiment of this application;

[0032] Figure 7 yes Figure 6 Enlarged structural diagram of section B;

[0033] Figure 8 yes Figure 6 Enlarged structural diagram of section C;

[0034] Figure 9 This is a schematic diagram of the antireflection membrane in the embodiments of this application.

[0035] Reference numerals: 1. Integrated composite substrate; 2. Arrayed fiber optic assembly; 3. Glass cover plate; 4. Temperature compensation module; 5. Base layer; 6. Light absorption intermediate layer; 7. Surface strengthening layer; 8. Straight V-groove; 9. Transmitter (TX) fiber optic group; 10. Receiver (RX) fiber optic group; 11. Top cover plate; 12. Bottom cover plate; 13. Inclined polished surface; 14. Groove; 15. SiO2 transition layer; 16. TiO2 high refractive index layer; 17. SiO2 low refractive index surface layer; 18. Encapsulation adhesive; 19. Metal compensation sheet; 20. Thermally conductive silicone; 21. Thermal insulation shell; 22. End face protective film; 23. Metal dust cover. Detailed Implementation

[0036] The following is in conjunction with the appendix Figures 1-9This application will be further described in detail below. The technical solutions in the embodiments of this application will be clearly described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0037] This application discloses a low-crosstalk, high-adaptability fiber optic array. For example... Figure 1 As shown, the substrate includes an integrated composite substrate 1. The base layer 5 of the integrated composite substrate 1 is borosilicate glass, the light-absorbing intermediate layer 6 is light-attenuating glass doped with Fe2O3-CoO-NiO (mass ratio 2:3:2, total doping amount 7wt%), and the surface strengthening layer 7 is a SiO2-TiO2 composite coating. Multiple straight V-grooves 8 are formed on the upper surface of the substrate; multiple straight V-grooves 8 are symmetrically formed on the lower surface, with the projection areas of the upper and lower straight V-grooves 8 misaligned. The overall light absorption rate of the substrate is 38dB, the light absorption coefficient is 12dB / mm, the refractive index is 1.52, and the coefficient of thermal expansion is 2.6×10⁻⁶. -6 / K.

[0038] The array fiber assembly 2 uses 16 single-mode fibers (9μm core / 125μm cladding / 250μm coating, NA=0.14, attenuation coefficient 0.2dB / km@1310nm), divided into transmitter (TX) fiber group 9 (8 fibers) and receiver (RX) fiber group 10 (8 fibers); the bare fiber segments are arranged without bending, and the fiber end face is coplanar with the substrate end face.

[0039] The glass cover 3 of the encapsulation structure is borosilicate glass, and the encapsulation adhesive 18 is a low refractive index modified epoxy resin (refractive index 1.44, containing 3wt% titanium black nanoparticles) with a light transmittance of 98.8%; the curing conditions are 80℃ / 2h + 120℃ / 1h.

[0040] The end face of the antireflection suppression structure has a grinding angle of 9°, a roughness Ra=0.006μm, and a perpendicularity of 0.08°. The antireflection film is adapted to a wavelength of 1310nm. The SiO2 transition layer 15 has a thickness of 41nm, the TiO2 high refractive index layer 16 has a thickness of 82nm, the SiO2 low refractive index surface layer 17 has a thickness of 82nm, and the reflectivity is 0.15%.

[0041] The metal compensation plate 19 of the temperature compensation module 4 is made of Invar steel with a coefficient of thermal expansion of 1.2 × 10⁻⁶. -6 / K, thermally conductive silicone 20 has a thermal conductivity of 1.8 W / (m·K), and the heat-insulating shell 21 is made of polyimide.

[0042] The end-face protective film 22 of the dustproof and protective component is made of PET material (99.2% light transmittance), and the metal dust cover 23 is made of aluminum alloy (IP54 dustproof rating).

[0043] A method for fabricating a low-crosstalk, high-adaptability fiber array includes the following steps:

[0044] S1. Substrate Preparation: A borosilicate glass substrate and a light-attenuating glass blank are selected, and a composite substrate base layer 5 and a light-absorbing intermediate layer 6 are prepared by high-temperature bonding process; SiO2-TiO2 sol is coated on the upper and lower surfaces of the composite substrate using the sol-gel method, and dried at 150℃ and sintered at 500℃ for 1 hour to form a surface strengthening layer 7; a precision diamond cutting machine is used to process straight V-grooves 8 on the upper and lower surfaces according to the design parameters, with a cutting speed of 5mm / s and a cutting depth control accuracy of ±1μm; the substrate is finely ground and polished to a surface flatness of 0.003mm, and a groove 14 is machined on the side for installing the temperature compensation module 4.

[0045] S2. Fiber optic assembly fabrication: Select 16 single-mode optical fibers and arrange them in an orderly manner using a fiber array sorting machine, with 8 fibers in each group (TX fiber group 9 for the transmitter and RX fiber group 10 for the receiver). Remove the coating layer from one end of the fiber to expose the bare fiber section. Grind the transition area between the bare fiber section and the coating layer into an arc. Place the sorted fiber groups into the straight V-grooves 8 on the upper and lower surfaces of the substrate, adjust the fiber position to ensure that the end faces are flush and coplanar with the end faces of the substrate, and fix them with temporary adhesive.

[0046] S3. Encapsulation and Curing: Using automated dispensing equipment, encapsulation adhesive 18 is evenly injected into the V-groove, with the injection volume being 92% of the V-groove volume; cover with glass cover plate 3, apply uniform pressure of 0.8N to ensure that the optical fiber is tightly attached to the V-groove without bubbles or excess adhesive; place in an oven and cure under the conditions of 80℃ / 2h + 120℃ / 1h, and remove the temporary fixing adhesive after curing.

[0047] S4. End face treatment: Fix the packaged fiber array on an angle grinding machine and perform rough grinding and fine grinding at a 9° tilt angle, using 15μm and 3μm diamond grinding wheels as grinding media; polish the end face with 0.1μm cerium oxide polishing slurry until the roughness Ra≤0.008μm; clean the end face to remove polishing slurry residue, and dry it for later use;

[0048] S5. Place the fiber array into the vacuum coating machine and evacuate the vacuum level to 5×10⁻⁶. -4 Pa; according to the designed film thickness, SiO2 transition layer 15, TiO2 high refractive index layer 16 and SiO2 low refractive index surface layer 17 are deposited sequentially, and the deposition rate is controlled at 0.5nm / s; after the film is coated, annealing treatment (200℃, 1h) is performed to improve the film adhesion.

[0049] S6. Temperature compensation and protection component installation: Apply thermally conductive silicone 20 into the groove 14 on the side of the substrate, embed the metal compensation piece 19, and press it firmly to fix it; install the heat insulation shell 21 and fix it with buckles; attach the end face protective film 22 and assemble the metal dust cover 23.

[0050] The implementation principle of a low crosstalk, high adaptability fiber optic array according to an embodiment of this application is as follows:

[0051] The upper surface of the substrate has a straight V-groove 8 to accommodate the RX fiber group, and the lower surface has a straight V-groove 8 to accommodate the TX fiber group. The projection areas of the two V-grooves are completely misaligned and do not overlap, avoiding direct interference between the signals of the upper and lower fiber layers. At the same time, the bare fiber segments are arranged without bending, eliminating bending loss and ensuring that the optical signal is transmitted without distortion along the fiber core.

[0052] The V-groove is precision-machined with a groove angle of 90°±2° and a groove wall roughness of ≤0.005μm. After the optical fiber is placed, it is positioned at the micron level by mechanical limiting of the V-groove. All optical fiber end faces are coplanar with the substrate end face. They are fixed by pressing the glass cover plate 3 and the encapsulation adhesive 18 to form a stable array end face, ensuring accurate docking with coupling components such as optical chips and lenses, and reducing coupling loss caused by alignment errors.

[0053] Each V-slot supports 8-16 optical fibers arranged in parallel, and a single array can integrate 16-32 channels of transceiver function. There is no need to splice independent TX / RX arrays, reducing the number of coupling interfaces and improving coupling efficiency by more than 35%. It is suitable for the multi-channel parallel transmission requirements of 800G / 1.6T optical modules.

[0054] The light-absorbing intermediate layer 6 (doped Fe2O3 / CoO / NiO composite oxide) of the integrated composite substrate 1 has a high absorption coefficient of 10-15dB / mm and an overall light absorption rate of 30-45dB. It can efficiently absorb scattered light leaked from adjacent channels and stray light reflected from the end face, blocking the spread of crosstalk signals from the source of the propagation path. The refractive index matching design (1.48-1.58) of the base layer 5 and the surface strengthening layer 7 further reduces light reflection and secondary scattering inside the substrate.

[0055] The fiber end face adopts an 8-12° (preferably 9°) tilt grinding design, so that the reflected light direction of the optical signal at the end face deviates from the fiber core (the reflection angle is tilted relative to the incident angle), avoiding the reflected light from being transmitted back to the light source or leaking to adjacent channels; at the same time, the end face is finely ground and polished (Ra≤0.008μm) to reduce scattering loss and reduce the basis for stray light generation.

[0056] A three-layer dielectric film consisting of a SiO2 transition layer 15, a TiO2 high-refractive-index layer 16, and a SiO2 low-refractive-index surface layer 17 is deposited on the inclined end face. The reflected light is destructively phased using the principle of optical interference. The film thicknesses are designed to be 1 / 8, 1 / 4, and 1 / 4 of the transmission wavelength, so that the phase difference of the reflected light at different film layer interfaces is 180°, which cancels each other out. The alternating layout of high-refractive-index (TiO2) and low-refractive-index (SiO2) film layers matches the refractive index difference between optical fiber and air, reducing the end face reflectivity from more than 4% of ordinary vertical end faces to ≤0.2%, which greatly reduces reflected stray light.

[0057] The encapsulating adhesive 18 adopts a low refractive index design of 1.42-1.46, which is close to the refractive index of the optical fiber cladding (1.468), reducing interface reflection; at the same time, 2-5wt% of nano-light-absorbing particles (carbon black, titanium black, etc.) are added, which can absorb a small amount of stray light leaking into the adhesive, further blocking crosstalk paths.

[0058] The coefficients of thermal expansion of the substrate base layer 5 (borosilicate glass / quartz glass), the light-absorbing intermediate layer 6 (light-attenuating glass), and the surface strengthening layer 7 (SiO2-TiO2 coating) are all controlled within 2.0 × 10⁻⁶. -6 ~2.8×10 -6 Within the range of / K, with the fiber cladding (0.5×10 -6 / K) forms a gradient transition, reducing the difference in thermal stress during temperature changes and avoiding substrate deformation or fiber displacement;

[0059] Temperature compensation module 4 (Invar / titanium alloy compensation sheet, coefficient of thermal expansion 1.0×10⁻⁶) embedded on the side of the substrate -6 ~1.5×10 -6 / K) is thermally coupled to the substrate through thermally conductive silicone 20; under high temperature environment, the thermal expansion of the substrate is greater than that of the compensation plate, and the compensation plate generates a reverse constraint force through its own low expansion characteristics to offset the excessive expansion of the substrate; under low temperature environment, the shrinkage of the substrate is greater than that of the compensation plate, and the rigid support of the compensation plate avoids the fiber from being deformed by pressure due to excessive shrinkage of the substrate, thereby stabilizing the relative position of the fiber and the V groove and ensuring coupling accuracy.

[0060] The modified epoxy resin adhesive with low water absorption (≤0.1%) and IP54 dustproof protection components block the corrosion of optical fiber end face and film layer by environmental factors such as water vapor and dust; the high shear strength of the adhesive (≥15MPa) ensures the fixation stability of the optical fiber and the substrate, avoiding performance fluctuations caused by loosening during temperature cycling.

[0061] The number of straight V-slots (8-16 per group), center spacing (0.25 / 0.5 / 1.0mm), and number of groups (2-4 groups) can be flexibly adjusted to adapt to the layout requirements of different optical modules such as four-channel / eight-channel / sixteen-channel optical chips and 800GDR8 / 1.6TDR16; the height spacing (1.0mm±0.1mm) and horizontal spacing (2.5mm±0.2mm) of the TX / RX groups are designed to be compatible with lens coupling schemes with 45° reflective prisms;

[0062] The thickness of the transmissive membrane can be adjusted according to the target wavelength (850nm / 1310nm / 1550nm / 1625nm). The thickness ratio of the three layers of the membrane is optimized through membrane system simulation to ensure that the reflectivity of different bands is ≤0.2%, which can take into account multiple application scenarios such as multimode communication (850nm), single-mode communication (1310 / 1550nm), and sensing (1625nm).

[0063] Lossless integration and precise coupling of transmitting and receiving optical fibers are achieved through staggered V-grooves; crosstalk signals are blocked throughout the entire link through multi-dimensional design of substrate absorption, tilted end face, antireflection film, and modified adhesive; structural deformation under extreme temperatures is offset through thermal matching and temperature compensation design; and the core functions of "high coupling efficiency, low crosstalk, wide temperature stability, and high adaptability" are finally achieved to meet the application requirements of high-end scenarios such as high-speed optical communication and large-scale sensing.

[0064] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A low-crosstalk, high-adaptability fiber optic array, comprising an integrated composite substrate (1), an array fiber optic assembly (2), a glass cover (3), an encapsulating adhesive (18), an anti-reflection and anti-reflection structure, and a temperature compensation module (4), characterized in that: The integrated composite substrate (1) is a layered composite structure, including a base layer (5), a light-absorbing intermediate layer (6) and a surface strengthening layer (7). The upper and lower surfaces of the integrated composite substrate (1) are respectively provided with N sets of parallel straight V grooves (8). The straight V grooves (8) on the upper surface and the straight V grooves (8) on the lower surface are arranged in the same direction and the projection areas are completely misaligned and do not overlap. The number of straight V grooves (8) in each set is 8-16. The center distance between adjacent straight V grooves (8) is 0.25mm, 0.5mm or 1.0mm. The array fiber optic assembly (2) includes a transmitter (TX) fiber optic group (9) and a receiver (RX) fiber optic group (10). The transmitter (TX) fiber optic group (9) and the receiver (RX) fiber optic group (10) each have 8-16 fibers, which are respectively housed in the straight V-grooves (8) on the lower and upper surfaces of the substrate. The bare fiber segments of the fibers are arranged without bending, and the end faces are coplanar with the end faces of the substrate. The fibers used in the transmitter (TX) fiber optic group (9) and the receiver (RX) fiber optic group (10) are single-mode fibers or multi-mode fibers. The single-mode fiber contains a single-mode fiber core, and the multi-mode fiber contains a multi-mode fiber core. The glass cover plate (3) is divided into an upper cover plate (11) and a lower cover plate (12), which are respectively pressed onto the upper straight V-grooves (8) and the lower straight V-grooves (8) on the upper and lower surfaces, and are fixedly connected to the integrated composite substrate (1) by an encapsulating adhesive (18). The antireflection suppression structure includes an inclined polished surface (13) on the end face of the optical fiber and a multilayer antireflection film deposited on the surface. The inclination angle of the end face is 8-12°, and the reflectivity of the antireflection film is ≤0.2%. The temperature compensation module (4) is embedded in the side groove (14) of the integrated composite substrate (1) and forms a thermal coupling with the integrated composite substrate (1). The overall light absorption rate of the integrated composite substrate (1) is 30-45dB, the light absorption coefficient of the light absorption intermediate layer (6) is 10-15dB / mm, the overall refractive index of the substrate is 1.48-1.58, and the coefficient of thermal expansion is 2.0×10. -6 ~2.8×10 -6 / K.

2. The low crosstalk, high adaptability fiber optic array according to claim 1, characterized in that: The base layer (5) of the integrated composite substrate (1) is made of borosilicate glass or quartz glass; the light absorption intermediate layer (6) is light attenuation glass doped with transition metal oxides, the transition metal oxides being one or more of Fe2O3, CoO, and NiO, with a total doping amount of 5-10wt%; the surface strengthening layer (7) is a SiO2-TiO2 composite coating prepared by sol-gel method, with a microhardness ≥800HV.

3. The low crosstalk, high adaptability fiber optic array according to claim 1, characterized in that: The distance between the transmitter (TX) fiber group (9) and the receiver (RX) fiber group (10) in the height direction is 1.0 mm ± 0.1 mm, and the center distance in the horizontal direction is 2.5 mm ± 0.2 mm. The core diameter of the single-mode fiber is 9 μm, the core diameter of the multimode fiber is 50 or 62.5 μm, the cladding diameter is 125 μm, and the coating diameter is 250 μm.

4. The low crosstalk, high adaptability fiber optic array according to claim 1, characterized in that: The straight V-groove (8) has a groove angle of 90°±2°, a groove depth of 62.5-125μm, a groove wall roughness Ra≤0.005μm, a length of 8-15mm, and a substrate reserved area width of 2-5mm between the two sets of straight V-grooves (8).

5. The low crosstalk, high adaptability fiber optic array according to claim 1, characterized in that: The antireflective coating is a three-layer dielectric film structure, consisting of a SiO2 transition layer (15), a TiO2 high refractive index layer (16), and a SiO2 low refractive index surface layer (17) from the optical fiber end face outwards. The thickness of each layer is 1 / 8, 1 / 4, and 1 / 4 of the transmission wavelength, respectively. The transmission wavelength is adapted to 850nm, 1310nm, 1550nm, or 1625nm. The antireflective coating has a friction resistance of ≥500 times.

6. The low crosstalk, high adaptability fiber optic array according to claim 1, characterized in that: The encapsulating adhesive (18) is a low refractive index modified epoxy resin with a refractive index of 1.42-1.46 and a light transmittance of ≥98.5%. 2-5 wt% of nano-sized light-absorbing particles with a particle diameter of 50-100 nm are added to the adhesive. The light-absorbing particles are carbon black, titanium black, or oxides doped with rare earth elements. The curing conditions of the adhesive are 80℃ / 2h + 120℃ / 1h. After curing, the shear strength is ≥15MPa and the water absorption rate is ≤0.1%.

7. The low crosstalk, high adaptability fiber optic array according to claim 1, characterized in that: The temperature compensation module (4) includes a metal compensation plate (19), thermally conductive silicone (20), and a heat insulation shell (21). The metal compensation plate (19) is made of Invar steel or titanium alloy, with a thickness of 1-2 mm and a coefficient of thermal expansion of 1.0 × 10⁻⁶. -6 ~1.5×10 -6 / K, the thermal conductivity of the thermally conductive silicone (20) is ≥1.5W / (m·K), and the heat insulation shell (21) is made of polyimide material with a thickness of 0.5-1mm.

8. A low-crosstalk, high-adaptability fiber optic array according to claim 1, characterized in that: The straight V-groove (8) on the upper surface of the substrate can be divided into 2-4 independent groups, with 4-8 straight V-groove (8) in each group. The spacing between the groups is 0.5-1.0 mm. The center lines of each group of straight V-groove (8) are parallel, which can meet the requirements of parallel coupling of multiple chips.

9. A low-crosstalk, high-adaptability fiber optic array according to claim 1, characterized in that: The fiber end face is finely ground and polished, with a roughness Ra≤0.008μm, end face perpendicularity≤0.1°, and coplanarity of all fiber end faces≤0.01mm; it also includes a dustproof protection component, which includes an end face protective film (22) and a metal dust cover (23). The end face protective film (22) is made of PET material with a light transmittance ≥99%, and the metal dust cover (23) is connected to the integrated composite substrate (1) through a snap-fit ​​structure, with a dustproof level of IP54.

10. A method for fabricating a low-crosstalk, high-adaptability fiber array, using the low-crosstalk, high-adaptability fiber array according to claim 9, characterized in that: It includes the following steps: S1. Substrate preparation: Borosilicate glass substrate and light-attenuating glass blank are selected and the base layer (5) and light-absorbing intermediate layer (6) of the composite substrate are prepared by high-temperature bonding process; SiO2-TiO2 sol is coated on the upper and lower surfaces of the integrated composite substrate (1) by sol-gel method, and then dried at 150℃ and sintered at 500℃ for 1h to form a surface strengthening layer (7); straight V grooves (8) on the upper and lower surfaces are processed by a precision diamond cutting machine tool at a cutting speed of 5mm / s and a cutting depth control accuracy of ±1μm; the substrate is finely ground and polished until the surface flatness is ≤0.003mm, and grooves (14) are processed on the side of the substrate. S2. Fiber optic assembly preparation: 16 single-mode optical fibers were selected and divided into a transmitter (TX) fiber group (9) and a receiver (RX) fiber group (10), with 8 fibers in each group. The fibers were arranged in an orderly manner by an optical fiber array sorting machine. The coating layer at one end of the fiber was removed to form a bare fiber segment. The transition area between the bare fiber segment and the coating layer was polished into an arc structure. The two groups of optical fibers were respectively placed in the straight V grooves (8) on the upper and lower surfaces of the substrate. The fiber was adjusted so that the end face was flush with the end face of the substrate and coplanar with the end face of the substrate. Temporary fixation adhesive was used to fix it. S3. Encapsulation and curing: The encapsulation adhesive (18) is injected into the straight V groove (8) using an automated dispensing device, with the injection amount being 92% of the volume of the straight V groove (8); the glass cover plate (3) is covered and a uniform pressure of 0.8N is applied to make the optical fiber and the straight V groove (8) fit tightly; after curing at 80℃ / 2h+120℃ / 1h, the temporary fixing adhesive is removed; S4. End face treatment: Fix the packaged fiber array to an angle grinding machine, and perform rough grinding and fine grinding with 15μm and 3μm diamond grinding wheels at a 9° tilt angle; polish with 0.1μm cerium oxide polishing fluid until the end face roughness Ra≤0.008μm; clean the end face and dry it; S5. Antireflection Coating Deposition: Place the fiber array inside a vacuum coating machine and evacuate to a vacuum level of 5×10⁻⁶. -4 Pa; SiO2 transition layer (15), TiO2 high refractive index layer (16) and SiO2 low refractive index surface layer (17) are deposited sequentially according to the designed thickness, and the deposition rate is controlled at 0.5 nm / s; after the coating is completed, it is annealed at 200℃ for 1 h; S6. Component installation: Apply thermally conductive silicone (20) to the groove (14) on the side of the substrate, insert the metal compensation piece (19) and press it firmly; install the heat insulation shell (21), paste the end face protective film (22) and assemble the metal dust cover (23).

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