CN215678960U

CN215678960U - Reflection type polarization-maintaining optical isolator

Info

Publication number: CN215678960U
Application number: CN202121673133.7U
Authority: CN
Inventors: 范臣臣; 文海丽; 曾天成; 张承鹏; 李京辉
Original assignee: Auxora Shenzhen Inc
Current assignee: Auxora Shenzhen Inc
Priority date: 2021-07-22
Filing date: 2021-07-22
Publication date: 2022-01-28
Anticipated expiration: 2031-07-22

Abstract

The utility model provides a reflective polarization-maintaining optical isolator, which relates to the field of laser sensing and comprises a packaging tube, wherein one end of the packaging tube is provided with at least one optical fiber capillary tube, an input polarization-maintaining optical fiber for optical fiber incidence and an output polarization-maintaining optical fiber for optical fiber emergence are inserted into the same side of each optical fiber capillary tube, and each optical fiber capillary tube corresponds to a group of isolation components; an optical lens for collimating the light beam passing through the isolation assembly is arranged in the other end of the packaging tube, and a reflector plate for reflecting the collimated light passing through the optical lens back to the isolation assembly is arranged on the rear side surface of the optical lens. Compared with the prior art, the input polarization-maintaining optical fiber and the output polarization-maintaining optical fiber are inserted into the same side of the reflective polarization-maintaining optical isolator, so that the size of the polarization-maintaining optical fiber isolator is reduced, the occupied space is reduced, and the reflective polarization-maintaining optical isolator can be mounted in a miniaturized mounting space and has better practical use convenience; and simple structure reduces production equipment spare and accessory parts, reduction in production cost, makes things convenient for manufacturing.

Description

Reflection type polarization-maintaining optical isolator

Technical Field

The utility model relates to the field of laser sensing, in particular to a reflective polarization-maintaining optical isolator.

Background

The optical fiber isolator is an important optical device in optical systems and equipment, and is an indispensable device in optical communication, lasers, amplifiers and light sources. The optical isolator is a passive device which allows light to pass through in one direction and prevents the light from passing through in the opposite direction, has the function of limiting the interface reflection of the light, ensures that the light can only be transmitted in a single direction, has the working principle of non-reciprocity based on Faraday rotation, and can well isolate the light reflected by echoes of various optical interfaces in an optical fiber system. The optical isolator mainly utilizes the faraday effect of the magneto-optical crystal. The characteristics of the optical isolator are: the forward insertion loss is low, the reverse isolation degree is high, and the return loss is high.

The conventional structure of a conventional fiber isolator is shown in fig. 1, and comprises an input collimator 1, an optical isolator core 2, and an output collimator 3, which are packaged in a fixed glass tube 4, wherein the input collimator 1 comprises an input optical fiber 11 and an input optical lens 12, the input optical fiber 11 is placed in an input bridging glass tube 13, the output collimator 3 comprises an output optical fiber 31 and an output optical lens 32, and the output optical fiber 31 is placed in an output bridging glass tube 33, so that two ends of the fixed glass tube 4 form an optical device structure with one input and one output. However, since the conventional fiber isolator has the optical fibers in two coaxial directions and the optical fibers have the limitation of minimum bending radius (the power transmitted by the optical fibers is lost after the minimum bending radius is exceeded), the use of the conventional fiber isolator is more limited in some small installation spaces; in addition, because the two sides of the traditional optical fiber isolator output fibers, 2 optical fiber collimators are required to be used for optical path coupling, more parts are used for production, and the cost is high.

SUMMERY OF THE UTILITY MODEL

Aiming at the problems, the utility model provides a reflective polarization-maintaining optical isolator which can occupy smaller space and has better actual use convenience in miniaturized installation space; and the structure is simple, and the production cost of the polarization maintaining fiber isolator is reduced.

The technical scheme adopted by the utility model is as follows:

the utility model provides a reflective polarization-maintaining optical isolator, includes the encapsulation pipe, and the one end of encapsulation pipe is equipped with at least one optic fibre capillary, its characterized in that: an input polarization maintaining optical fiber for optical fiber incidence and an output polarization maintaining optical fiber for optical fiber emergence are inserted into the same side of each optical fiber capillary, and each optical fiber capillary corresponds to a group of isolator core components; an optical lens for collimating the light beam passing through the isolator core assembly is arranged in the other end of the packaging tube, and a reflecting sheet for reflecting the collimated light passing through the optical lens back to the isolator assembly is arranged on the rear side surface of the optical lens; the isolator core assembly comprises an input polaroid corresponding to the end face slow axis direction of the input polarization maintaining optical fiber, a Faraday rotator arranged on the input polaroid and used for rotating the polarization direction of a light beam passing through the input polaroid, and an output polaroid arranged on one side of the input polaroid and corresponding to the slow axis direction of the output polarization maintaining optical fiber and used for coupling the light beam reflected by the reflector and passing through the optical lens into the output polarization maintaining optical fiber.

Preferably, the slow axis of the input polarization maintaining fiber and the slow axis of the output polarization maintaining fiber are at an angle of 45 degrees.

More preferably, the polarization directions of the input polarizer and the output polarizer are at an angle of 45 °.

More preferably, the polarization direction of each polarizer itself is within ± 2 ° of the geometric orientation tolerance of the physical dimensions of the polarizer.

Preferably, the Faraday rotator is a magnetism-keeping Faraday rotator.

Preferably, the reflecting sheet is an optical glass plane, and the surface of the reflecting sheet is coated with a reflecting film.

Preferably, the optical lens and the packaging tube are bonded by glue.

Compared with the prior art, the utility model has the beneficial effects that: the utility model provides a reflective polarization-maintaining optical isolator, which is characterized in that an input polarization-maintaining optical fiber and an output polarization-maintaining optical fiber are inserted into the same side, so that the size of the polarization-maintaining optical fiber isolator is reduced, the occupied space is reduced, and the reflective polarization-maintaining optical isolator can be mounted in a miniaturized mounting space and has better practical use convenience; the structure is simple, the production and assembly parts are reduced, the production cost is reduced, and the production and the manufacture are convenient; in addition, the poor extinction ratio caused by the angle difference of the slow axes of the input optical fiber and the output optical fiber can be measured in advance, the poor products can be stopped at the semi-finished product stage in advance, and the actual production cost of the product can be reduced to a certain extent.

Drawings

FIG. 1 is a schematic diagram of a conventional fiber optic isolator;

FIG. 2 is a schematic diagram of a reflective polarization maintaining optical isolator according to the present invention;

FIG. 3 is a schematic diagram of a fiber optic capillary in a reflective polarization maintaining optical isolator according to the present invention;

FIG. 4 is a schematic end view of a fiber optic capillary in a reflective polarization maintaining optical isolator according to the present invention;

FIG. 5 is a schematic diagram of an isolation component in a reflective polarization maintaining optical isolator according to the present invention;

FIG. 6 is a schematic diagram of an isolation assembly mounted on a fiber capillary in a reflective polarization maintaining optical isolator according to the present invention.

Detailed Description

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 2 to 6 show a preferred embodiment of a reflective polarization-maintaining optical isolator according to the present invention. As shown in fig. 2 to 6, the reflective polarization-maintaining optical isolator includes a package tube 10, one end of the package tube 10 is provided with at least one optical fiber capillary 20, an input polarization-maintaining optical fiber 21 for optical fiber incidence and an output polarization-maintaining optical fiber 22 for optical fiber emergence are inserted into the same side of each optical fiber capillary 20, and each optical fiber capillary corresponds to a group of isolator core assemblies 30; an optical lens 40 for collimating light beams passing through the isolator core assembly is arranged in the other end of the packaging tube 10, a reflector 50 for reflecting collimated light passing through the optical lens back to the isolator assembly is arranged on the rear side face of the optical lens 40, so that light input by the input polarization maintaining optical fiber 21 passes through the isolator core assembly after being processed and then passes through the optical lens 40 to form collimated light, and the collimated light is reflected by the reflector 50, passes through the optical lens 40 and the isolator assembly 30, enters the output polarization maintaining optical fiber 22 and is output by the output polarization maintaining optical fiber 22. The reflective sheet 50 is a flat optical glass surface coated with a reflective film. The coating medium of the reflector plate can be air or glue, and can be selected according to the design of the product for bearing power.

The isolator core assembly 30 comprises an input polarizer 31 corresponding to the slow axis of the input polarization maintaining fiber and used for coupling an input optical fiber, a faraday rotator 32 arranged on the input polarizer and used for rotating the polarization direction of a light beam passing through the input polarizer, and an output polarizer 33 arranged on one side of the input polarizer and corresponding to the slow axis of the output polarization maintaining fiber and used for coupling the optical fiber reflected by a reflector and passing through an optical lens into the output polarization maintaining fiber, wherein an input optical signal input by the input polarization maintaining fiber 21 forms polarized light through the input polarizer 31, the polarized light enters the optical lens 40 after the polarization direction of the polarized light is adjusted by the faraday rotator 32 to form collimated light, the collimated light is reflected by the reflector 50, passes through the optical lens 40, then passes through the output polarizer and enters the output polarization maintaining fiber 22, and thus the forward transmission of a light path is formed; on the other hand, when returning light generated by various factors in the system enters the output polarization maintaining fiber 22 and propagates, the polarization direction formed by the backward rotation of the returning light entering the faraday rotator after passing through the output polarizer 33 and the reflector 50 is opposite to the polarization direction in the forward transmission, and light having a polarization direction different from the self polarization direction is absorbed by the polarizer, as is known from the malus law, thereby forming a function of isolating the reflected light.

It should be noted that polarization-maintaining fibers operate by inducing a difference in the optical speed in two perpendicular polarizations through the fiber, and this birefringence produces two main transmission axes within the fiber, called the fast and slow axes of the polarization-maintaining fiber, respectively: the fast axis is the direction with small refractive index, and the optical axis with higher optical transmission speed vertically passes through the midpoint of the connecting line of the centers of the two stress areas; the slow axis is an optical axis passing through the end points of the two stress regions, is in the direction with large refractive index, and has a slow transmission speed. Therefore, the connecting line direction of the polarization maintaining fiber cat eye is a slow axis, and the vertical direction is a fast axis.

The relative included angle of the slow axes of the input polarization maintaining optical fiber and the output polarization maintaining optical fiber is 45 degrees, and the slow axis direction is the connecting line direction of the stress areas of the polarization maintaining optical fibers. The polarization direction of the input optical signal is adjusted to be consistent with the slow axis direction of the input optical fiber, so that the transmission in the horizontal polarization direction in the input optical fiber is kept.

The polarization directions of the input polarizer 31 and the output polarizer 33 form an angle of 45 °. And the angle tolerance between the polarization direction of the polaroid and the physical dimension and geometric direction of the polaroid is within +/-2 degrees. The thickness of the polaroid has various specifications, and the specification of the general product in the market is suitable for the thickness of 0.2 mm. In general, the input polarizer 31 is a 0 ° polarizer, and an input optical signal input to the polarization maintaining fiber 21 is linearly polarized at 0 ° by the input polarizer 31.

The faraday rotator 32 is a magnetic maintaining type faraday rotator, the material of which is capable of keeping magnetization, and the working magnetic field of which drives without needing permanent external magnetic field, thus omitting other components such as magnetic block/ring providing magnetic field from outside, and solving the space size of the whole device. It should be noted that the faraday rotator 32 may also be a non-magnetic-retaining faraday rotator, and only needs to provide a corresponding external magnetic field, such as a magnetic block/magnetic ring, in the working area of the faraday rotator, so as to achieve the purpose of adjusting the polarization direction. The linearly polarized light of 0 ° formed by the input polarizer 31 is rotated by the re-faraday rotator 32 to be transmitted in a direction of 45 °.

The whole assembly process of the reflection type polarization maintaining optical isolator comprises the following steps: 1) assembling the fiber capillary 20: after the input polarization maintaining fiber 21 and the output polarization maintaining fiber 22 are inserted into the fiber capillary 20, the slow axis angle of the output polarization maintaining fiber 22 is adjusted to 45 degrees according to the horizontal direction of the input polarization maintaining fiber 21, and then the slow axis angle is fixed by glue. According to the parameter requirements of the final device, the narrow angle tolerance of the slow axes of the 102 polarization maintaining optical fiber and the 103 polarization maintaining optical fiber is just within +/-2 degrees, so that the extinction ratio of the key parameter of the polarization maintaining optical fiber isolator can be ensured to be more than or equal to 20 dB; 2) assembling the polarization isolator core assembly 30: fixing an input polaroid 31 and a Faraday rotator 32 with the same size by glue, and correspondingly attaching the input polaroid 31 to the horizontal (0 degree) input polarization-maintaining optical fiber 21 on the end face of the optical fiber capillary 20 according to the identification of the input polaroid 31; then correspondingly pasting the mark corresponding to the output polaroid 33 on the optical fiber capillary 20 end face to output the polarization maintaining optical fiber 22 with an included angle of 45 degrees; 3) bonding the optical lens 40 and the packaging tube 10 by glue, inserting the optical fiber capillary tube 20 pasted with the polarization isolation assembly 30 into the packaging tube 10 to debug the light spot parameters until the qualified light spot parameters meet the design requirements; 4) the optical fiber coupler is coupled and debugged with the reflector plate 50 on a debugging tool, input light enters the output optical fiber through the input optical fiber, the optical isolator and the reflector plate in a coupling mode, a forward light path is formed, and the design passing loss is met.

In summary, the technical solution of the present invention can fully and effectively achieve the above objects of the present invention, and the structure and functional principle of the present invention have been fully verified in the embodiments, so as to achieve the expected efficacy and purpose, and without departing from the principle and essence of the present invention, various changes or modifications can be made to the embodiments of the present invention. Accordingly, this invention includes all modifications encompassed within the scope of the claims appended hereto, and any equivalents thereof which fall within the scope of the claims appended hereto.

Claims

1. The utility model provides a reflective polarization-maintaining optical isolator, includes the encapsulation pipe, and the one end of encapsulation pipe is equipped with at least one optic fibre capillary, its characterized in that: an input polarization maintaining optical fiber for optical fiber incidence and an output polarization maintaining optical fiber for optical fiber emergence are inserted into the same side of each optical fiber capillary, and each optical fiber capillary corresponds to a group of isolator core components; an optical lens for collimating the light beam passing through the isolation assembly is arranged in the other end of the packaging tube, and a reflector plate for reflecting the collimated light passing through the optical lens back to the isolation assembly is arranged on the rear side surface of the optical lens; the isolator core assembly comprises an input polaroid corresponding to the end face slow axis direction of the input polarization maintaining optical fiber, a Faraday rotator arranged on the input polaroid and used for rotating the polarization direction of a light beam passing through the input polaroid, and an output polaroid arranged on one side of the input polaroid and corresponding to the end face slow axis direction of the output polarization maintaining optical fiber and used for coupling the light beam reflected by the reflector and passing through the optical lens into the output polarization maintaining optical fiber.

2. The reflective polarization-maintaining optical isolator of claim 1, wherein: the slow axis relative included angle of the input polarization maintaining optical fiber and the output polarization maintaining optical fiber is 45 degrees.

3. The reflective polarization-maintaining optical isolator of claim 1, wherein: the polarization directions of the input polaroid and the output polaroid form an included angle of 45 degrees.

4. The reflective polarization-maintaining optical isolator of claim 1, wherein: the angle tolerance between the polarization direction of each polaroid and the physical dimension geometric direction of the polaroid is within +/-2 degrees.

5. The reflective polarization-maintaining optical isolator of claim 1, wherein: the Faraday rotator is a magnetism-keeping Faraday rotator.

6. The reflective polarization-maintaining optical isolator of claim 1, wherein: the reflecting sheet is an optical glass plane, and the surface of the reflecting sheet is coated with a reflecting film.

7. The reflective polarization-maintaining optical isolator of claim 1, wherein: the optical lens and the packaging tube are bonded by glue.