CN-121995579-A - Double-groove polarization maintaining coupler and coupling packaging method

CN121995579ACN 121995579 ACN121995579 ACN 121995579ACN-121995579-A

Abstract

The invention provides a double-groove polarization maintaining coupler and a coupling packaging method. The double-groove polarization-maintaining coupler comprises a coupler assembly and a packaging shell assembly for protecting the coupler assembly, wherein the coupler assembly comprises a lithium niobate optical waveguide chip, an input polarization-maintaining tail fiber arranged on the input side of the lithium niobate optical waveguide chip in a coupling mode, and a double-groove output polarization-maintaining tail fiber arranged on the output side of the lithium niobate optical waveguide chip in a coupling mode, and the double-groove output polarization-maintaining tail fiber comprises two micro-nano V-shaped grooves arranged side by side. The coupling packaging method comprises the steps of equipment pretreatment, tail fiber pretreatment, input polarization-maintaining tail fiber treatment, input polarization-maintaining tail fiber preliminary alignment, input polarization-maintaining tail fiber fine alignment, double-groove output polarization-maintaining tail fiber alignment, dispensing solidification treatment and packaging. According to the technical scheme, high-efficiency mode field matching is realized through double-slot coupling, the coupling efficiency and the polarization maintaining capability can be obviously improved while the size of the device is reduced, and long-term stable operation of the device in various application environments is ensured through a high-robustness packaging process.

Inventors

RAO QINGQING
DENG XINGHU
ZHANG LONGLONG
CHEN XUXING

Assignees

上海傲世控制科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260205

Claims (10)

1. The double-groove polarization-maintaining coupler is characterized by comprising a coupler assembly and a packaging shell assembly for protecting the coupler assembly; the coupler assembly comprises a lithium niobate optical waveguide chip, an input polarization maintaining tail fiber arranged on the input side of the lithium niobate optical waveguide chip in a coupling way, and a double-groove output polarization maintaining tail fiber arranged on the output side of the lithium niobate optical waveguide chip in a coupling way; the double-groove output polarization-maintaining tail fiber comprises two micro-nano V-shaped grooves which are arranged side by side.
2. The double-slot polarization-maintaining coupler according to claim 1, wherein the lithium niobate optical waveguide chip is an X-cut Y-propagating lithium niobate chip prepared by focused ion beam etching and proton exchange process, and has a cutting angle of 10 °, a length of 12mm, and a width of 2.8mm.
3. The double-slot polarization-maintaining coupler according to claim 1, wherein the slot pitch of two V-shaped slots is 250 μm, the slot depth of the V-shaped slots is 60±10 μm, and the angle is 15 °.
4. The dual slot polarization maintaining coupler of claim 1, wherein the input polarization maintaining pigtail and the dual slot output polarization maintaining pigtail are bare fiber stripped of coating.
5. The dual slot polarization maintaining coupler of claim 1 wherein the housing assembly comprises an inner housing sleeve, a middle housing sleeve, and an outer housing sleeve.
6. The coupling packaging method of the double-slot polarization-maintaining coupler according to any one of claims 1 to 5, wherein the coupling packaging method is realized based on a coupling system, and the coupling system comprises an SLD polarization-maintaining light source, an accurate counter-axis coupling platform, an optical power meter, an extinction ratio tester, an LED point light source curing machine and a visual system; the coupling packaging method comprises the following steps: Equipment pretreatment, namely starting the SLD depolarization light source, the optical power meter, the extinction ratio tester, the LED point light source curing machine and the visual system; Preparing a prepared lithium niobate optical waveguide chip, an input polarization maintaining tail fiber and a double-groove output polarization maintaining tail fiber, stripping coating layers from tail fiber ends of the input polarization maintaining tail fiber and the double-groove output polarization maintaining tail fiber, and cleaning; The input polarization maintaining tail fiber is welded to the output jumping end of the SLD polarization eliminating light source, the optical power meter and the extinction ratio tester are adopted to test the optical power and the extinction ratio of the end face of the input polarization maintaining tail fiber, the recording optical power is P 0 , and the extinction ratio is PER 0 ; The input polarization maintaining tail fiber is initially aligned, namely the end face of the input polarization maintaining tail fiber is aligned with the input of the lithium niobate optical waveguide chip under the visual system; The input polarization maintaining tail fiber is precisely aligned, the alignment precision is adjusted through the precise shaft coupling platform, and the angle of the input polarization maintaining tail fiber is adjusted under the monitoring of the optical power meter, so that the stress shaft of the input polarization maintaining tail fiber is completely aligned with the polarization main shaft of the lithium niobate optical waveguide chip; The end face of the double-slot output polarization-maintaining tail fiber penetrates into an adapter and is inserted into a channel of the optical power meter, an optical power value P 1 、P 2 is recorded under the condition that a stress axis of the double-slot output polarization-maintaining tail fiber is completely aligned with a polarization main axis of the lithium niobate optical waveguide chip, and then the double-slot output polarization-maintaining tail fiber is inserted into the channel of the extinction ratio tester, and an extinction ratio PER 1 、PER 2 is recorded; dispensing and solidifying, namely dispensing and solidifying the coupling points of the lithium niobate optical waveguide chip and the input polarization-maintaining tail fiber and the coupling points of the lithium niobate optical waveguide chip and the double-groove output polarization-maintaining tail fiber, and solidifying the ultraviolet glue at each coupling point by adopting the LED point light source solidifying machine; And packaging, namely packaging the coupler assembly by adopting a packaging shell assembly.
7. The method of claim 6, wherein in the step of processing the input polarization maintaining pigtail, the SLD depolarization light source uses 1310nm and 1550nm operating wavelengths; and/or the number of the groups of groups, In the step of processing the input polarization maintaining tail fiber, the measuring range of the optical power meter is-70 dBm to +10dBm.
8. The coupling packaging method of the double-slot polarization-maintaining coupler according to claim 6, wherein in the step of processing the input polarization-maintaining tail fiber, the input optical power range of the extinction ratio tester is-40 dBm to +10dBm; and/or the number of the groups of groups, In the step of dispensing curing treatment, the working wavelength of the LED point light source curing machine is 365nm wave band.
9. The coupling packaging method of the double-slot polarization-maintaining coupler according to claim 6, wherein the accurate counter-axis coupling platform is a six-dimensional displacement platform, and the displacement directions are an X direction, a Y direction, a Z direction and a theta X 、θ Y 、θ Z direction.
10. The coupling packaging method of the double-slot polarization-maintaining coupler according to claim 6, wherein the optical power meter automatically calculates the insertion loss and the spectral ratio according to the recorded optical power P 0 、P 1 、P 2 based on the following formula; the expression of insertion loss is: The expression of the spectral ratio is: Wherein, IL is insertion loss, D is a split ratio, P 0 is optical power input to the polarization-maintaining fiber, and P 1 、P 2 is optical power output from the polarization-maintaining fiber by double slots.

Description

Double-groove polarization maintaining coupler and coupling packaging method Technical Field The invention belongs to the technical field of integrated optical devices, and particularly relates to a double-groove polarization maintaining coupler and a coupling packaging method. Background The integrated optical device of lithium niobate (LiNbO 3) has been widely used in the fields of high-speed optical fiber communication, high-precision optical fiber sensing (such as optical fiber gyro), quantum information processing, and the like due to its excellent electro-optical, acousto-optic and nonlinear optical characteristics. The polarization maintaining fiber can maintain the polarization state of the optical signal, and is a key medium for realizing stable transmission in the system. The polarization maintaining coupler is used as a core interface device for connecting the polarization maintaining fiber and the lithium niobate waveguide, and the performance of the polarization maintaining coupler directly determines the light path efficiency and stability of the whole system. Currently, the mainstream scheme for realizing the optical waveguide coupling of the polarization maintaining optical fiber and the lithium niobate chip is a three-terminal direct end-face coupling technology. Although the technology has a relatively simple structure, the technology has obvious bottleneck in practical application and further miniaturization and high performance: 1. the input end and the output end need to be aligned and fixed on different end surfaces or side surfaces of the chip, so that a large space is occupied, and miniaturization and high-density integration of the device are limited. 2. The existence of a plurality of coupling points leads to the increase of accumulated tolerance, so that the consistency of key parameters such as Insertion Loss (IL) and light splitting ratio (D) is difficult to accurately control, and the yield is influenced. 3. Polarization maintaining performance, namely, the traditional single-point or single-slot coupling structure has limited mode matching capability on an optical field, and particularly, the capability of distinguishing two orthogonal polarization modes of polarization maintaining light is insufficient, so that polarization crosstalk is higher, and extinction ratio (PER) performance is difficult to improve. 4. The long-term reliability is that the prior packaging technology has insufficient protection on a plurality of fragile coupling interfaces, and the performance of the device is easy to drift or even lose efficacy when the device faces severe environments such as temperature circulation, mechanical vibration or humidity change. Therefore, for the application scenarios such as the fiber optic gyroscope, which have strict requirements on the device size, the performance consistency, the polarization maintaining capability and the long-term reliability, a novel coupling structure and a novel coupling packaging scheme are needed. Disclosure of Invention In view of the above, the present invention provides a dual-slot polarization maintaining coupler and a coupling packaging method. According to a first aspect of the present invention, there is provided a double-slot polarization maintaining coupler comprising a coupler assembly and a package housing assembly for protecting the coupler assembly; the coupler assembly comprises a lithium niobate optical waveguide chip, an input polarization maintaining tail fiber arranged on the input side of the lithium niobate optical waveguide chip in a coupling way, and a double-groove output polarization maintaining tail fiber arranged on the output side of the lithium niobate optical waveguide chip in a coupling way; the double-groove output polarization-maintaining tail fiber comprises two micro-nano V-shaped grooves which are arranged side by side. Alternatively, the X-cut Y-transmitted lithium niobate optical waveguide chip prepared by the focused ion beam etching and proton exchange process has a cutting angle of 10 degrees, a length of 12mm and a width of 2.8mm. Alternatively, the groove distance between two V-shaped grooves is 250 μm, the groove depth of the V-shaped grooves is 60+/-10 μm, and the angle is 15 degrees. Optionally, the ends of the input polarization-maintaining tail fiber and the double-groove output polarization-maintaining tail fiber are bare fibers with stripped coating layers. Optionally, the packaging housing assembly includes an inner packaging sleeve, a middle packaging sleeve, and an outer packaging sleeve. According to a second aspect of the invention, a coupling packaging method of any one of the above dual-groove polarization maintaining couplers is provided, wherein the coupling packaging method is realized based on a coupling system, and the coupling system comprises an SLD polarization eliminating light source, an accurate counter-shaft coupling platform, an optical power meter, an extinction ratio teste