阅读说明：本技术 一种基于Gouy相移的光纤模式分离方法和装置 (Gouy phase shift-based optical fiber mode separation method and apparatus ) 是由 兰名荥 王子琪 高立 李俊晖 喻松 杨家利 项阳阳 于 2019-12-02 设计创作，主要内容包括：本发明涉及一种基于Gouy相移的光纤模式分离方法和装置,该方法通过利用Gouy相位差产生相长干涉的方式,完成光场模式的分离,其中,选用渐变折射率光纤实现Gouy相位的累积。相应的装置依据该方法进行设计。该装置包括光纤分束模块、光纤Gouy相位产生模块、光纤干涉模块；所述光纤分束模块将光束一分为二；所述光纤Gouy相位产生模块包含两段光纤,光束经过该模块后产生光纤中模式分离所需的Gouy相位差；光束在所述光纤干涉模块中基于Gouy相位差发生相长干涉,最终实现模式分离。本发明实现了光纤中基于Gouy相移的光场模式分离,同时光纤模式分离装置的体积比空间中缩小数个量级,便于操作与集成化,可应用于全光纤通信系统。(The invention relates to a Gouy phase shift-based optical fiber mode separation method and a Gouy phase shift-based optical fiber mode separation device. The corresponding device is designed according to the method. The device comprises an optical fiber beam splitting module, an optical fiber Gouy phase generating module and an optical fiber interference module; the optical fiber beam splitting module divides a light beam into two parts; the optical fiber Gouy phase generation module comprises two sections of optical fibers, and light beams pass through the optical fiber Gouy phase generation module to generate Gouy phase difference required by mode separation in the optical fibers; the light beams generate constructive interference in the optical fiber interference module based on Gouy phase difference, and mode separation is finally achieved. The Gouy phase shift-based optical field mode separation device realizes the Gouy phase shift-based optical field mode separation in the optical fiber, and meanwhile, the volume of the optical fiber mode separation device is reduced by several orders of magnitude in space, so that the optical fiber mode separation device is convenient to operate and integrate, and can be applied to all-fiber communication systems.)

1. An optical fiber mode splitting apparatus based on Gouy phase shift, the apparatus comprising:

the optical fiber Gouy phase generation device comprises an optical fiber beam splitting module, an optical fiber Gouy phase generation module and an optical fiber interference module;

the output end of the optical fiber beam splitting module is divided into two paths, and the light beam is divided into two parts;

the optical fiber Gouy phase generation module comprises two optical fibers, the input ends of the two optical fibers are respectively connected with the two output ends of the optical fiber beam splitting module, the output ends of the two optical fibers are connected with the two input ends of the optical fiber interference module, and light beams generate Gouy phase difference required by mode separation in the optical fibers after passing through the optical fiber Gouy phase generation module;

the output end of the optical fiber interference module is divided into two paths, and constructive interference occurs in the module by utilizing the generated Gouy phase difference to realize mode separation.

2. The Gouy phase-shifting-based fiber mode splitting device as claimed in claim 1, wherein the fiber Gouy phase generation module comprises a graded-index fiber and a step-index fiber.

3. The Gouy phase shift-based fiber mode splitting device as claimed in claim 1, wherein the fiber Gouy phase generation module is composed of two graded-index fibers with different parameters.

4. The Gouy phase-shift-based optical fiber mode splitting device as claimed in claim 1, wherein the optical fiber Gouy phase generation module is composed of two optical fibers with the same parameter and graded index, and an optical fiber 'U' -shaped groove, one optical fiber with the same parameter and graded index is selected to be placed in the optical fiber 'U' -shaped groove, and the optical fiber is deformed through a knob to change the refractive index distribution of the optical fiber, so that a Gouy phase difference is generated.

5. A method for fiber mode splitting based on Gouy phase shift, the method comprising:

two beams of identical light beams pass through two sections of special optical fibers with different parameters to generate Gouy phase difference, and mode separation is realized by utilizing the phase difference to generate constructive interference.

6. The method as claimed in claim 5, wherein the Gouy phase shift-based fiber mode splitting method is characterized in that the Gouy phase of the light beam is accumulated by using a graded index fiber, and the accumulated Gouy phase value is different when the parameters of the graded index fiber are different.

Technical Field

The invention belongs to the technical field of optical fiber space division multiplexing, and particularly relates to a Gouy phase shift-based optical fiber mode separation method and device.

Background

To solve the contradiction between the rapidly increasing bandwidth demand and the capacity limit of optical fiber, technologies such as wavelength division multiplexing, space division multiplexing, etc. have come to be used, and among them, mode division multiplexing, which is one of the space division multiplexing technologies, is recognized as one of the most promising methods for greatly increasing the optical communication capacity. Mode separation is one of the key technologies of mode division multiplexing, and previous people have realized mode separation of laguerre-gaussian beams according to orbital angular momentum in an optical fiber and separation of optical field modes based on Gouy phase shift in space in the direction, wherein, the method for realizing the mode separation of the latter mode is as follows: different optical devices such as lenses, beam splitters and the like are inserted into two arms of the interferometer, the distance between the two arms is adjusted to generate Gouy phase difference, and the mode separation purpose is finally achieved by the constructive interference principle generated by the phase difference.

The above studies indicate that, although mode separation has been achieved based on Gouy phase shift, it must be accomplished using spatial optics, is not implemented in optical fiber, cannot be applied to all-fiber communication systems, and a complete mode separation device in space is bulky and difficult to cascade and integrate.

Therefore, there is a need to provide a novel mode separation method and apparatus to solve the above problems.

Disclosure of Invention

The invention aims to provide a Gouy phase shift-based optical fiber mode separation method and device, and aims to solve the problems that the optical fiber mode separation method and device cannot be realized in an optical fiber and are large in size in the prior art.

In order to achieve the above object, the present invention provides a Gouy phase shift-based optical fiber mode splitting apparatus, comprising:

the device comprises an optical fiber beam splitting module (1), an optical fiber Gouy phase generating module (2) and an optical fiber interference module (3);

the output end of the optical fiber beam splitting module (1) is divided into two paths, and a light beam is divided into two paths;

the optical fiber Gouy phase generation module (2) comprises two optical fibers, the input ends of the two optical fibers are respectively connected with the two output ends of the optical fiber beam splitting module (1), the output ends of the two optical fibers are connected with the two input ends of the optical fiber interference module (3), and the light beams generate Gouy phase difference required by mode separation in the optical fibers after passing through the optical fiber Gouy phase generation module (2);

the output end of the optical fiber interference module (3) is divided into two paths, and constructive interference occurs in the module by utilizing the generated Gouy phase difference to realize mode separation.

Optionally, the optical fiber Gouy phase generation module (2) is composed of a graded-index optical fiber and a step-index optical fiber.

Optionally, the fiber Gouy phase generation module (2) is composed of two graded index fibers with different parameters.

Optionally, the optical fiber Gouy phase generation module (2) is composed of two optical fibers with the same parameters and the same gradient index, and an optical fiber U-shaped groove (4), one optical fiber with the same parameters and the same gradient index is placed in the optical fiber U-shaped groove (4), and the optical fiber is deformed through a knob to change the refractive index distribution of the optical fiber, so that the Gouy phase difference is generated.

The invention also provides an optical fiber mode separation method based on Gouy phase shift, which is characterized by comprising the following steps:

two beams of identical light beams pass through two sections of special optical fibers with different parameters to generate Gouy phase difference, and constructive interference is generated by utilizing the phase difference to finally realize mode separation.

Alternatively, Gouy phase accumulation is achieved using graded index fibers, where the accumulated Gouy phase values are different when the graded index fiber parameters are different.

The mode separation device overcomes the defects in previous research, realizes the separation of the optical field mode in the optical fiber based on Gouy phase shift, and has a series of advantages of small volume, easy cascade, application to all-fiber communication systems and the like.

Drawings

FIG. 1 is a block diagram of the apparatus of the present invention;

FIG. 2 is a system block diagram of the apparatus of the present invention;

FIG. 3 is a block diagram of the combination of the fiber "U" groove (4) and the fiber in the device of the present invention;

FIG. 4 is a block diagram of the cascade of the apparatus of the present invention.

The optical fiber Gouy phase generating module comprises an optical fiber beam splitting module 1, an optical fiber Gouy phase generating module 2, an optical fiber interference module 3 and an optical fiber U-shaped groove 4.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the method and apparatus of the present invention are further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.