阅读说明：本技术 一种全光纤模式复用/解复用器 (All-fiber mode multiplexer/demultiplexer ) 是由 吕家亮 李宏勋 姚培军 许立新 于 2020-07-09 设计创作，主要内容包括：本发明公开了一种全光纤模式复用/解复用器,包括两根相同的少模光纤。少模光纤拉锥区的涂覆层均已剥去,熔融拉锥至工作波长的直径和长度,工作波长可根据实际需求设定,实现模式复用和解复用功能,此过程无需对少模光纤进行预拉锥处理。本发明首次提出了实现全光纤模式复用/解复用的方法,两根少模光纤采用全光纤熔融耦合方式,构成的光纤模式复用/解复用器结构紧凑,制作简单,插入损耗小,耦合效率高。本发明可以应用于光纤通信、光学信息处理等领域。(The invention discloses an all-fiber mode multiplexer/demultiplexer, which comprises two same few-mode fibers. The coating layers of the few-mode optical fiber tapering region are stripped, the taper is melted to the diameter and the length of the working wavelength, the working wavelength can be set according to actual requirements, the mode multiplexing and demultiplexing functions are realized, and pre-tapering treatment is not needed to be carried out on the few-mode optical fiber in the process. The invention provides a method for realizing all-fiber mode multiplexing/demultiplexing for the first time, two few-mode fibers adopt an all-fiber fusion coupling mode, and the formed fiber mode multiplexing/demultiplexing device has the advantages of compact structure, simple manufacture, small insertion loss and high coupling efficiency. The invention can be applied to the fields of optical fiber communication, optical information processing and the like.)

1. An all-fiber mode multiplexer/demultiplexer comprising: two identical few-mode optical fibers, characterized in that: the coating layers of the tapering areas of the few-mode optical fibers are stripped, the tapering is fused to the diameter and the length of the working wavelength, and the working wavelength can be set according to actual requirements, so that the mode multiplexing and demultiplexing functions can be realized.

2. The all-fiber mode multiplexer/demultiplexer of claim 1, wherein: the mode multiplexing function is that an all-fiber fused tapering method is adopted to draw two same few-mode fibers to a specific size, a basic mode and a high-order mode are respectively input from the two few-mode fibers, the same mode coupling occurs in a tapering coupling area, and the basic mode and the high-order mode are simultaneously output at the output end of one few-mode fiber.

3. The all-fiber mode multiplexer/demultiplexer of claim 1, wherein: the mode demultiplexing function is that a mixed mode is input from one few-mode optical fiber, and two few-mode optical fibers at the output end respectively output a basic mode and a high-order mode.

4. The all-fiber mode multiplexer/demultiplexer of claim 1, wherein: the length from the fused biconical taper to the working wavelength is even or odd times of the length of the coupling half period of the fundamental mode, and odd or even times of the length of the coupling half period of the high-order mode.

Technical Field

The invention belongs to the technical field of optical fiber couplers, and particularly relates to an all-fiber mode multiplexer/demultiplexer which can be applied to the fields of optical fiber communication, optical information processing and the like.

Background

With the rapid development of information communication technology, the demand of communication networks for bandwidth and capacity has increased explosively, while the existing optical fiber communication field is based on single-mode optical fiber, and the transmission capacity of single-mode optical fiber has approached the transmission capacity of the nonlinear shannon limit. Various methods have been proposed to increase communication capacity, including Wavelength Division Multiplexing (WDM) and polarization multiplexing (PDM). In recent years, the Mode Division Multiplexing (MDM) technology is widely considered as an effective way to break through the bottlenecks of single-mode optical fiber communication systems and transmission capacities, and the technology can greatly improve the communication capacity. The mode division multiplexer has gained wide attention as a key device in the mode division multiplexing system, and the current technologies for manufacturing the mode division multiplexer mainly include two types: the first mode is a mode division multiplexer based on a space optical element, three modes are coupled to the same multimode optical fiber by utilizing a phase wave plate, but the mode division multiplexer has the disadvantages of high space coupling difficulty, difficulty in integration, high space coupling insertion loss and high manufacturing cost; the spatial light modulator can flexibly generate various complex light fields to realize the mode division multiplexing, but the manufacturing cost of the spatial light modulator is higher. The second type is a mode division multiplexer with an optical fiber structure, a plurality of single-mode optical fibers are inserted into a capillary with low refractive index, a photon lantern is formed through fused tapering, and the photon lantern meets phase matching conditions of different modes in a fundamental mode of each single-mode optical fiber and a multimode optical fiber by using the single-mode optical fibers with different fiber cores, so that mode division multiplexing is realized. But photon lantern mould division multiplexer manufacturing process is complicated, and accurate control fusion optical fiber position, the thickness degree of difficulty is very big, can't realize the volume production, and the photon lantern can lead to the high loss when the optical fiber butt fusion does not match simultaneously.

Disclosure of Invention

The invention aims to solve the defects of complex manufacturing process, large insertion loss, high manufacturing cost, difficulty in integration and the like of the conventional mode division multiplexer/demultiplexer, and provides an all-fiber mode multiplexer/demultiplexer.

In order to achieve the purpose, the technical scheme of the invention is as follows: an all-fiber mode multiplexer/demultiplexer comprising: the coating layers of the tapering areas of the two same few-mode optical fibers are stripped, the mode multiplexing and demultiplexing functions can be realized by melting tapering to the diameter and the length of the working wavelength, and the few-mode optical fibers do not need to be subjected to pre-tapering treatment in the process.

The mode multiplexing function is that an all-fiber fused tapering method is adopted to draw two same few-mode fibers to a specific size, a basic mode and a high-order mode are respectively incident from the two few-mode fibers, evanescent field self-coupling occurs in a tapering coupling area of the basic mode and the high-order mode, and the basic mode and the high-order mode are simultaneously output at the output end of one few-mode fiber.

The mode demultiplexing function is that a mixed mode is input from one of the few-mode optical fibers, and two few-mode optical fibers at the output end respectively output a fundamental mode and a high-order mode.

The length of the coupling region from the fused biconical taper to the working wavelength is even or odd times of the length of the basic mode coupling half period, and is odd or even times of the length of the high-order mode coupling half period.

The invention has the following beneficial effects:

(1) the invention adopts two few-mode optical fibers to carry out all-fiber fused tapering manufacture mode multiplexer/demultiplexer, does not need to carry out pre-tapering treatment on the few-mode optical fibers, and has simple manufacture process and small insertion loss.

(2) The invention realizes LP₀₁And LP₁₁Mode multiplexing and demultiplexing of the two modes.

(3) The invention uses the standard communication optical fiber (G.652) as few-mode optical fiber, has low manufacturing cost, can be produced in mass and has strong practicability.

(4) The invention adopts an all-fiber structure, has compact structure and easy integration, can be packaged by packaging materials, and has stable work without being interfered by external factors.

(5) The invention has the mode stripping function and high mode purification efficiency, and realizes the high-quality single fundamental mode or single high-order mode output by the fiber laser.

Drawings

Fig. 1 is a schematic structural diagram of an all-fiber mode multiplexer/demultiplexer according to the present invention.

FIG. 2 is simulation LP of Rsoft software₀₁Energy monitoring graph of mode in the tapering coupling region, wherein FIG. 2(a) is LP in the coupling region₀₁Intensity distribution of pattern, LP in FIG. 2(b)₀₁Graph of power change of the mode at FMF1 channel.

FIG. 3 is simulation LP of Rsoft software₁₁Mode is pullingCone coupling region energy monitoring diagram, wherein FIG. 3(a) is LP in the coupling region₁₁Intensity distribution of pattern, LP in FIG. 3(b)₁₁Graph of power change of the mode at FMF1 channel.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings in combination with the specific embodiments.