A fiber mode multiplexing and demultiplexing device supporting polarization multiplexing

Abstract

The invention discloses an optical fiber mode multiplexing and demultiplexing device supporting polarization multiplexing, which includes a programmable optical mode selective excitation and multiplexing system composed of a silicon-based liquid crystal, a Faraday rotator and a polarization beam splitter; Under the condition of zero damage to the polarization multiplexing signal, high-isolation selective excitation of fiber modes, multiplexing and demultiplexing of six spatial and polarization modes are realized. The invention utilizes a piece of silicon-based liquid crystal to realize the selective excitation of four polarization and spatial modes including the polarization state at the same time, and simultaneously couples the fundamental mode light field with the polarization multiplexing signal into the few-mode optical fiber, thereby realizing six spatial modes and polarization mode multiplexing.

Description

technical field [0001] The invention relates to the field of optical communication, and relates to an optical fiber mode multiplexing and demultiplexing device supporting polarization multiplexing. Background technique [0002] Mode multiplexing technology is to use the spatial dimension of the optical field distribution in the optical fiber, and use multiple modes to transmit different information respectively, so as to achieve the purpose of improving the capacity of the optical fiber communication system; at the same time, due to the increase of the effective area of ​​the optical fiber core, the The damage to the optical signal caused by the nonlinearity of the fiber is avoided, and the key to limit the development of this technology lies in the precise mode selective excitation and coupling scheme. [0003] After literature research and patent retrieval, the liquid crystal-based mode multiplexing devices mentioned in the current literature have few multiplexed modes, th...

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Problems solved by technology

[0004] In the prior art, a mode excitation and coupling scheme based on multimode interference (MMI) is proposed, which uses the multimode interference generated by the connection of "single-mode fiber-multimode fiber-single-mode fiber" to realize mode excitation. The problem with this scheme is that the modes that can be excited can only be some low-order modes, and are limited by the working wavelength. At the same time, the accuracy of the excited mode is affected by environmental factors, and the practicability is not strong.

The mode coupling scheme of multi-core fiber to few-mode fiber is also proposed. Although this method is an all-fiber structure, it has large insertion loss, large inter-mode interference and inter-mode crosstalk, and is not suitable for exciting modes with complex mode field distributions. , nor is it suitable for modes whose mode field distribution is circular, such as LP 0m model

In addition, there are literatures that use long-period fiber gratings to achieve selective excitation of modes. The disadvantages of this method are that the writing of the grating is complicated, it is greatly affected by temperature, and the dynamic range of the working wavelength is very narrow. It is not applicable to the combination of division multiplexing and mode division multiplexing

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