阅读说明：本技术 一种用于光子晶体光纤组件耦合的方法 (method for coupling photonic crystal fiber assembly ) 是由 白国财 郑国康 黄韬 刘瑞丹 周建伟 丁东发 夏君磊 于 2019-07-19 设计创作，主要内容包括：本发明提供一种用于光子晶体光纤组件耦合的方法,包括：清洗波导芯片和尾纤；固定芯片和尾纤；确定芯片输出端位置；调节尾纤位置,找到消光比和功率的最大输出点；耦合点胶,曝光粘接,尾纤保护。本发明的方法,能够实现光子晶体光纤的耦合而且不堵塞其空气空隙,操作便捷,并且提高了光子晶体光纤连接的可靠性。(the invention provides a method for coupling a photonic crystal fiber assembly, which comprises the following steps: cleaning the waveguide chip and the tail fiber; fixing the chip and the tail fiber; determining the position of the output end of the chip; adjusting the position of the tail fiber to find the maximum output point of the extinction ratio and the power; coupling dispensing, exposure bonding and tail fiber protection. The method can realize the coupling of the photonic crystal fiber without blocking the air gap, is convenient and fast to operate, and improves the reliability of the connection of the photonic crystal fiber.)

1. A method for photonic crystal fiber assembly coupling, comprising the steps of:

a1, wiping the coupling end face of the chip by a cotton swab dipped with alcohol;

A2, fixing the chip, the input end tail fiber and the output end tail fiber on the optical platform;

a3, cutting an inlet optical fiber of an input end tail fiber, then accessing a red light source, and adjusting the relative position of the input end tail fiber and the chip input end through an optical platform until a red light spot is found at the chip output end;

a4, connecting an entrance fiber of an input end tail fiber to a light source, connecting a chip output end to an optical power meter through an output end tail fiber, adjusting the positions of the input end tail fiber and the output end tail fiber relative to the chip until a maximum output power point is found, coating coupling adhesive glue on the fiber coupling end face of the input end tail far away from the fiber cladding, and exposing and curing;

a5, coating coupling adhesive glue on the coupling end face of the tail fiber at the output end far away from the fiber cladding, and exposing and curing;

A6, coating protective glue on the root of the optical fiber on the end face of the input end tail fiber and the root of the optical fiber on the end face of the output end tail fiber; thereby completing the coupling of the photonic crystal fiber.

2. a method for photonic crystal fiber assembly coupling according to claim 1, wherein: the optical platform is a six-dimensional optical adjusting frame and provides six-degree-of-freedom adjustment, and the six-degree-of-freedom adjustment comprises six degrees of freedom of up-down, left-right, internal rotation and external rotation.

3. A method for photonic crystal fiber assembly coupling according to claim 1, wherein: the coupling bonding glue is ultraviolet curing glue, the viscosity of the protective glue is larger than that of the coupling bonding glue, the viscosity range of the protective glue is 20000-30000 cps, the viscosity range of the coupling bonding glue is 300-1000 cps, and the refractive index range is 1.45-1.55.

4. A method for photonic crystal fiber assembly coupling according to claim 1, wherein: the input end tail fiber and the output end tail fiber have the same structure and are prepared by the following steps:

S1, etching a wafer V-shaped groove on the silicon wafer;

s2, cutting the silicon wafer with the V-shaped groove into a plurality of arrays;

S3, grinding the array, wherein the end face of the array is ground into an inclined plane;

s4, cutting the array into a plurality of discrete units, wherein each discrete unit is provided with one and only one wafer V-shaped groove;

S5, cleaning and drying the V-shaped groove of the wafer on each discrete unit;

S6, clamping the photonic crystal fiber on the fiber clamp, so that the end face of the photonic crystal fiber is positioned at the center of a microscope field of view;

S7, stretching the photonic crystal fiber out of the fiber head of the fiber clamp, stripping the coating layer by using a fiber thermal puller, vertically cutting the fiber head of the bare fiber by using a fiber cutter to enable the end face of the bare fiber to be flat, and carrying out the first-time axis fixing of the photonic crystal fiber;

S8, putting the optical fiber head which passes through the S7 dead axle and extends out of the optical fiber fixture on an optical fiber cutter, and fixing the optical fiber head through a first fixing device and a second fixing device, wherein the cutter head of the optical fiber cutter is positioned between the first fixing device and the second fixing device and is used for cutting the photonic crystal optical fiber between the first fixing device and the second fixing device;

S9, placing the optical fiber cut in the S8 mode into the wafer V-shaped groove on the discrete unit processed in the S5 mode, enabling the polarization maintaining axis of the photonic crystal optical fiber to be parallel to the upper surface of the wafer V-shaped groove on the discrete unit through a horizontal CCD, controlling the length of the optical fiber extending out of the wafer V-shaped groove on the discrete unit through a vertical CCD, coating fixed axis adhesive glue, and performing ultraviolet exposure curing to complete secondary fixed axis of the photonic crystal optical fiber, so that the preparation of the photonic crystal optical fiber assembly is completed.

5. the method of claim 4, wherein the coupling comprises: the viscosity range of the fixed-axis bonding glue is 200-500 cps, and the requirement of refractive index is avoided.

6. the method of claim 4, wherein the coupling comprises: the wafer V-shaped grooves etched on the silicon wafer in the step S1 have the depth of 45-52 μm, the width of 95-105 μm, and the distance between the adjacent wafer V-shaped grooves of 1.3-1.6 mm;

when silicon wafers are cut into arrays, the silicon wafers are cut in the direction perpendicular to the V-shaped grooves of the wafers, and the length of the V-shaped grooves of the wafers in each array obtained by cutting is the same and is 1.9 mm-2.2 mm.

7. The method of claim 4, wherein the coupling comprises: in step S3, the array is ground, and the end face of the array is ground into an inclined plane, specifically: the array is ground to a form with a length of 1.8mm to 2mm and an end face at an angle of 15 DEG + -0.5 deg.

8. the method of claim 4, wherein the coupling comprises: step S4 cuts the array into a plurality of discrete units, specifically: the cutting direction is parallel to the wafer V-shaped grooves on the array, each discrete unit is provided with only one wafer V-shaped groove, and the end face of each discrete unit is an angle of 15 degrees +/-0.5 degrees.

9. The method of claim 4, wherein the coupling comprises: in step S6, the optical fiber clip specifically includes: the optical fiber fixing seat (1), the cover plate (2), the optical fiber positioning device (3) and the dead axle device (4);

The section of the fixed shaft device (4) is Z-shaped, the optical fiber fixing seat (1) is assembled on the upper surface of the fixed shaft device (4), a fixture V-shaped groove is formed in the optical fiber fixing seat (1), the photonic crystal optical fiber extending out of the optical fiber positioning device (3) is placed in the fixture V-shaped groove, the photonic crystal optical fiber is tightly pressed in the fixture V-shaped groove through the cover plate (2), and the length of the photonic crystal optical fiber extending out of the fixture V-shaped groove is adjusted;

the fixed axis of the primary photonic crystal fiber specifically comprises: and enabling the polarization maintaining axis of the photonic crystal fiber to be vertical to the upper surface of the V-shaped groove of the clamp on the fiber clamp, and then fixing the fiber.

10. the method of claim 4, wherein the coupling comprises: the cutting of the photonic crystal fiber between the first fixing device and the second fixing device specifically comprises the following steps: after the photonic crystal fiber is fixed, the second fixing device is rotated by 90 degrees, the photonic crystal fiber between the first fixing device and the second fixing device is twisted by 90 degrees, and after the cutter head cuts the photonic crystal fiber, the photonic crystal fiber forms an end face angle of a 15-degree inclined plane.

11. The method of claim 4, wherein the coupling comprises: the length of the optical fiber extending out of the V-shaped groove of the wafer on the discrete unit is controlled to be less than 50 mu m by the vertical CCD.

Technical Field

the invention relates to a connection process of a photonic crystal fiber, in particular to a method for coupling a photonic crystal fiber component.

background

the coupling of the optical waveguide is essentially a connection of the optical fiber and the chip in six degrees of freedom. The common polarization maintaining fiber is greatly influenced by the environment and has poor temperature stability, so that the application range of the common polarization maintaining fiber is greatly limited by the environment, but the photonic crystal fiber has the advantages of low bending loss, high birefringence, low dispersion, high temperature stability and the like, and provides a brand-new solution for the poor environmental adaptability of the common polarization maintaining fiber. And the photonic crystal fiber has high birefringence, and can keep good polarization state transmission even under the action of external force, temperature and radiation.

however, in engineering application, due to the existence of holes in the end face configuration of the photonic crystal fiber, the coupling glue flows into the holes in the end face of the photonic crystal fiber when being dispensed according to the original optical fiber coupling method, the hole structure of the photonic crystal fiber has a siphon effect, the light path bonding glue is generally ultraviolet curing glue and has strong fluidity, and under the siphon effect, the adhesive can be sucked into the holes for a certain distance, so that the light transmission efficiency is rapidly reduced, and even light cannot be transmitted. The coupling adhesive belongs to an optical path adhesive, which plays a role in optical path adhesion and refractive index matching of a chip and an optical fiber, and ultraviolet adhesive with good fluidity is uniformly distributed on an adhesive surface through the interaction of the chip and the optical fiber to enhance the adhesion. Therefore, the dispensing process needs to be controlled, which can ensure both the bonding reliability and the maximum light transmission energy.

Disclosure of Invention

The technical problem solved by the invention is as follows: in the method for connecting by using the photonic crystal fiber, a novel photonic crystal fiber coupling method is provided, and the method avoids blocking air holes of the photonic crystal fiber and improves the connection precision of an optical path of the fiber by controlling the glue dispensing position and the glue dispensing amount.

The above purpose of the invention is realized by the following technical scheme:

the invention discloses a coupling method for a photonic crystal fiber assembly, which comprises the following steps:

a method for photonic crystal fiber assembly coupling, comprising the steps of:

A1, wiping the coupling end face of the chip by a cotton swab dipped with alcohol;

A2, fixing the chip, the input end tail fiber and the output end tail fiber on the optical platform;

A3, cutting an inlet optical fiber of an input end tail fiber, then accessing a red light source, and adjusting the relative position of the input end tail fiber and the chip input end through an optical platform until a red light spot is found at the chip output end;

A4, connecting an entrance fiber of an input end tail fiber to a light source, connecting a chip output end to an optical power meter through an output end tail fiber, adjusting the positions of the input end tail fiber and the output end tail fiber relative to the chip until a maximum output power point is found, coating coupling adhesive glue on the fiber coupling end face of the input end tail far away from the fiber cladding, and exposing and curing;

a5, coating coupling adhesive glue on the coupling end face of the tail fiber at the output end far away from the fiber cladding, and exposing and curing;

A6, coating protective glue on the root of the optical fiber on the end face of the input end tail fiber and the root of the optical fiber on the end face of the output end tail fiber; thereby completing the coupling of the photonic crystal fiber.

The optical platform is a six-dimensional optical adjusting frame and provides six-degree-of-freedom adjustment, and the six-degree-of-freedom adjustment comprises six degrees of freedom of up-down, left-right, internal rotation and external rotation.

the coupling bonding glue is ultraviolet curing glue, the viscosity of the protective glue is larger than that of the coupling bonding glue, the viscosity range of the protective glue is 20000-30000 cps, the viscosity range of the coupling bonding glue is 300-1000 cps, and the refractive index range is 1.45-1.55.

The input end tail fiber and the output end tail fiber have the same structure and are prepared by the following steps:

S1, etching a wafer V-shaped groove on the silicon wafer;

S2, cutting the silicon wafer with the V-shaped groove into a plurality of arrays;

S3, grinding the array, wherein the end face of the array is ground into an inclined plane;

s4, cutting the array into a plurality of discrete units, wherein each discrete unit is provided with one and only one wafer V-shaped groove;

S5, cleaning and drying the V-shaped groove of the wafer on each discrete unit;

s6, clamping the photonic crystal fiber on the fiber clamp, so that the end face of the photonic crystal fiber is positioned at the center of a microscope field of view;

S7, stretching the photonic crystal fiber out of the fiber head of the fiber clamp, stripping the coating layer by using a fiber thermal puller, vertically cutting the fiber head of the bare fiber by using a fiber cutter to enable the end face of the bare fiber to be flat, and carrying out the first-time axis fixing of the photonic crystal fiber;

s8, putting the optical fiber head which passes through the S7 dead axle and extends out of the optical fiber fixture on an optical fiber cutter, and fixing the optical fiber head through a first fixing device and a second fixing device, wherein the cutter head of the optical fiber cutter is positioned between the first fixing device and the second fixing device and is used for cutting the photonic crystal optical fiber between the first fixing device and the second fixing device;

S9, placing the optical fiber cut in the S8 mode into the wafer V-shaped groove on the discrete unit processed in the S5 mode, enabling the polarization maintaining axis of the photonic crystal optical fiber to be parallel to the upper surface of the wafer V-shaped groove on the discrete unit through a horizontal CCD, controlling the length of the optical fiber extending out of the wafer V-shaped groove on the discrete unit through a vertical CCD, coating fixed axis adhesive glue, and performing ultraviolet exposure curing to complete secondary fixed axis of the photonic crystal optical fiber, so that the preparation of the photonic crystal optical fiber assembly is completed.

The viscosity range of the fixed-axis bonding glue is 200-500 cps, and the requirement of refractive index is avoided.

the wafer V-shaped grooves etched on the silicon wafer in the step S1 have the depth of 45-52 μm, the width of 95-105 μm, and the distance between the adjacent wafer V-shaped grooves of 1.3-1.6 mm;

When silicon wafers are cut into arrays, the silicon wafers are cut in the direction perpendicular to the V-shaped grooves of the wafers, and the length of the V-shaped grooves of the wafers in each array obtained by cutting is the same and is 1.9 mm-2.2 mm.

in step S3, the array is ground, and the end face of the array is ground into an inclined plane, specifically: the array is ground to a form with a length of 1.8mm to 2mm and an end face at an angle of 15 DEG + -0.5 deg.

Step S4 cuts the array into a plurality of discrete units, specifically: the cutting direction is parallel to the wafer V-shaped grooves on the array, each discrete unit is provided with only one wafer V-shaped groove, and the end face of each discrete unit is an angle of 15 degrees +/-0.5 degrees.

In step S6, the optical fiber clip specifically includes: the optical fiber fixing seat (1), the cover plate (2), the optical fiber positioning device (3) and the dead axle device (4);

the section of the fixed shaft device (4) is Z-shaped, the optical fiber fixing seat (1) is assembled on the upper surface of the fixed shaft device (4), a fixture V-shaped groove is formed in the optical fiber fixing seat (1), the photonic crystal optical fiber extending out of the optical fiber positioning device (3) is placed in the fixture V-shaped groove, the photonic crystal optical fiber is tightly pressed in the fixture V-shaped groove through the cover plate (2), and the length of the photonic crystal optical fiber extending out of the fixture V-shaped groove is adjusted;

The fixed axis of the primary photonic crystal fiber specifically comprises: and enabling the polarization maintaining axis of the photonic crystal fiber to be vertical to the upper surface of the V-shaped groove of the clamp on the fiber clamp, and then fixing the fiber.

the cutting of the photonic crystal fiber between the first fixing device and the second fixing device specifically comprises the following steps: after the photonic crystal fiber is fixed, the second fixing device is rotated by 90 degrees, the photonic crystal fiber between the first fixing device and the second fixing device is twisted by 90 degrees, and after the cutter head cuts the photonic crystal fiber, the photonic crystal fiber forms an end face angle of a 15-degree inclined plane.

the length of the optical fiber extending out of the V-shaped groove of the wafer on the discrete unit is controlled to be less than 50 mu m by the vertical CCD.

The invention has the beneficial effects that:

(1) Compared with the traditional photonic crystal fiber connection method, glue overflows to the end face of the optical fiber after the glue is dispensed on the end face of the fixed block, the siphon effect is easily caused due to the small size of the cavity on the end face of the photonic crystal fiber, and the glue overflowing to the surface is sucked into the cavity for a certain distance, so that the air hole of the optical fiber is blocked.

(2) the method of the invention needs to coat protective glue with high viscosity on the root parts of the optical fibers on the end faces of the input end and the output end tail fibers to protect the tail fibers.

(3) The invention researches a high-reliability low-loss connection process of the photonic crystal fiber, and fundamentally breaks through the bottleneck of hindering the engineering production of the photonic crystal fiber gyroscope. In the photonic crystal fiber connection technology, coupling glue is required to be prevented from being dispensed into a photonic fiber cavity during glue dispensing, so that the siphon effect of the fiber cavity is avoided, the shape of an optical transmission mode field is ensured not to change, and the output optical power is maximum.

drawings

FIG. 1 is a flow chart of a coupling method used in the present invention;

FIG. 2 is a schematic view of a coupling device used in the present invention;

FIG. 3 is a schematic diagram of the coupling of a chip and an optical fiber according to the present invention.

Detailed Description

a method for coupling a photonic crystal fiber assembly according to the present invention will be described in further detail with reference to the accompanying drawings and embodiments.

as shown in fig. 1, a method for photonic crystal assembly coupling includes the steps of:

a1, wiping the coupling end face of the chip by a cotton swab dipped with alcohol;

A2, fixing the chip, the input end tail fiber and the output end tail fiber on the optical platform; the optical platform is a six-dimensional optical adjusting frame and provides six-degree-of-freedom adjustment, including six degrees of freedom of up-down, left-right, internal rotation and external rotation.

a3, cutting an inlet optical fiber of an input end tail fiber, then accessing a red light source, and adjusting the relative position of the input end tail fiber and the chip input end through an optical platform until a red light spot is found at the chip output end;

In practice, the input end tail fiber and the output end tail fiber are arranged on a six-dimensional adjusting frame of an optical platform, and the positions of the tail fibers are adjusted until the brightest point appears at the position of the output end of the chip, so that the positions of the input end and the output end are determined.

a4, connecting an entrance fiber of an input end tail fiber to a light source, connecting a chip output end to an optical power meter through an output end tail fiber, adjusting the positions of the input end tail fiber and the output end tail fiber relative to the chip until a maximum output power point is found, coating coupling adhesive glue on the fiber coupling end face of the input end tail far away from the fiber cladding, and exposing and curing;

A5, coating coupling adhesive glue on the coupling end face of the tail fiber at the output end far away from the fiber cladding, and exposing and curing; as shown in fig. 3.

A6, coating protective glue on the root of the optical fiber on the end face of the input end tail fiber and the root of the optical fiber on the end face of the output end tail fiber; thereby completing the coupling of the photonic crystal fiber.

the coupling adhesive is optical ultraviolet curing adhesive and has optical performance and adhesive performance, the viscosity of the protective adhesive is larger than that of the coupling adhesive, the viscosity range of the protective adhesive is 20000-30000 cps, the viscosity range of the coupling adhesive is 300-1000 cps, and the refractive index is 1.45-1.55.

Further, the invention provides a preparation method of input end tail fibers and output end tail fibers, which comprises the following steps:

S1, etching a wafer V-shaped groove on the silicon wafer;

the wafer V-shaped grooves etched on the silicon wafer in the step S1 have a depth of 55 um-65 um and a width of 85 um-95 um, and the distance between the adjacent wafer V-shaped grooves is 25 um-35 um.

s2, cutting the silicon wafer with the V-shaped groove into a plurality of arrays;

When silicon wafers are cut into arrays, the silicon wafers are cut in the direction perpendicular to the V-shaped grooves of the wafers, and the length of the V-shaped grooves of the wafers in each array obtained by cutting is the same and is 2.2-2.2 um.

S3, grinding the array, wherein the end face of the array is ground into an inclined plane;

The method specifically comprises the following steps: the array is ground to a form with a length of 1.8mm to 2mm and an end face at an angle of 15 DEG + -0.5 deg. The purpose is to match a 15 ° angled photonic crystal fiber.

s4, cutting the array into a plurality of discrete units, wherein each discrete unit is provided with one and only one wafer V-shaped groove;

the method specifically comprises the following steps: the cutting direction is parallel to the wafer V-shaped grooves on the array, each discrete unit is provided with only one wafer V-shaped groove, and the end face of each discrete unit is an angle of 15 degrees +/-0.5 degrees.

s5, cleaning and drying the V-shaped groove of the wafer on each discrete unit;

S6, clamping the photonic crystal fiber on the fiber clamp, so that the end face of the photonic crystal fiber is positioned at the center of a microscope field of view;

The optical fiber fixture specifically includes: the optical fiber fixing seat comprises an optical fiber fixing seat 1, a cover plate 2, an optical fiber positioning device 3 and a fixed shaft device 4;

The section of the fixed shaft device 4 is Z-shaped, the optical fiber fixing seat 1 is assembled on the upper surface of the fixed shaft device 4, a fixture V-shaped groove is formed in the optical fiber fixing seat 1, the photonic crystal optical fiber extending out of the optical fiber positioning device 3 is placed in the fixture V-shaped groove, the photonic crystal optical fiber is tightly pressed in the fixture V-shaped groove through the cover plate 2, and the length of the photonic crystal optical fiber extending out of the fixture V-shaped groove is adjusted.

s7, enabling the photonic crystal fiber to extend out of the fiber head of the fiber clamp to strip the coating layer by 15-20 mm through a fiber thermal puller, vertically cutting the bare fiber by 9-15 mm through a fiber cutter to enable the end face of the bare fiber to be flat, and carrying out primary axis fixing on the photonic crystal fiber.

the fixed axis of the primary photonic crystal fiber specifically comprises: and rotating the photonic crystal fiber to enable the polarization maintaining axis of the photonic crystal fiber to be vertical to the upper surface of the V-shaped groove of the fixture, and then fixing the fiber. The first axis fixing is to determine the polarization maintaining axial direction of the photonic crystal fiber, so that the end face of the photonic crystal fiber is conveniently cut into a specific angle.

The width of the V-shaped groove of the fixture is 158-162 mu m, and the depth of the V-shaped groove of the fixture is 68-76 mu m.

S8, putting the optical fiber head which passes through the S7 dead axle and extends out of the optical fiber fixture on an optical fiber cutter, and fixing the optical fiber head through a first fixing device and a second fixing device, wherein the cutter head of the optical fiber cutter is positioned between the first fixing device and the second fixing device and is used for cutting the photonic crystal optical fiber between the first fixing device and the second fixing device;

the cutting of the photonic crystal fiber between the first fixing device and the second fixing device specifically comprises the following steps: after the photonic crystal fiber is fixed, the second fixing device is rotated by 90 degrees, the photonic crystal fiber between the first fixing device and the second fixing device is twisted by 90 degrees, and after the cutter head cuts the photonic crystal fiber, the photonic crystal fiber forms an end face angle of a 15-degree inclined plane.

s9, placing the optical fiber cut in the S8 mode into the wafer V-shaped groove on the discrete unit processed in the S5 mode, enabling the polarization maintaining axis of the photonic crystal optical fiber to be parallel to the upper surface of the wafer V-shaped groove on the discrete unit through a horizontal CCD, controlling the length of the optical fiber extending out of the wafer V-shaped groove on the discrete unit through a vertical CCD, coating a proper amount of ultraviolet curing glue, exposing and curing, and thus completing the second axis fixing of the photonic crystal optical fiber and completing the preparation of the photonic crystal optical fiber assembly. The length of the optical fiber extending out of the wafer V-groove on the discrete cell is controlled by the vertical CCD to be less than 50 μm as shown in fig. 2.

the invention researches a high-reliability low-loss connection process of the photonic crystal fiber, and fundamentally breaks through the bottleneck of hindering the engineering production of the photonic crystal fiber gyroscope. In the photonic crystal fiber connection technology, coupling glue is required to be prevented from being dispensed into a photonic fiber cavity during glue dispensing, so that the siphon effect of the fiber cavity is avoided, the shape of an optical transmission mode field is ensured not to change, and the output optical power is maximum.