Cascade sum-frequency and difference-frequency all-optical wavelength converter and conversion method

Abstract

The invention discloses a cascade sum-frequency and difference-frequency all-optical wavelength converter and a conversion method. After second pump light of a second laser device of the converter is transmitted through a polarization controller, a linearly polarized light conversion device and a first optical coupler, the second pump light and signal light access a second optical coupler, an erbium-doped fiber amplifier and an optical circulator together and reach a PPLN (periodically poled lithium niobate) ridge waveguide, forward light beams are reflected by a Faraday 90-degree rotating reflector, backward light beams are transmitted into the ridge waveguide, and converted idler-frequency light is outputted from the optical circulator. The conversion method includes adjusting the pump light into a TM (transverse magnetic) mode by the polarization controller, and then converting the pump light into linearly polarized light by the online polarized light conversion device; decomposing the linearly polarized light into light in a TE (transverse electric) mode and light in a TM mode in the ridge waveguide; enabling the pump light in the TM mode and the signal light in a TM mode to perform cascade sum-frequency and difference-frequency reaction and generating the converted idler-frequency light in a TM mode; reflecting other forward light and converting a mode of the other forward light by the aid of the Faraday reflector; returning the other forward light to the ridge waveguide. The polarization direction of the linearly polarized light is parallel to the cross section of the PPLN ridge waveguide, and an angle theta is formed between the linearly polarized light and an X-axis. An amplitude ratio of the light in the TE mode to the light in the TM mode is tg theta. The cascade sum-frequency and difference-frequency all-optical wavelength converter and the conversion method have the advantage that wavelength conversion independent from a polarization state of the signal light can be implemented by the aid of the cascade sum-frequency and difference-frequency all-optical wavelength converter and the conversion method.

Description

technical field [0001] The invention belongs to the technical field of optical communication, and specifically relates to a cascaded sum-frequency and difference-frequency all-optical wavelength converter and a conversion method, that is, a cascaded sum-frequency and difference-frequency all-optical wavelength conversion based on a PPLN optical waveguide The device and conversion method are mainly applicable to dense wavelength division multiplexing optical communication systems. Background technique [0002] In the field of optical communication technology, high-capacity and high-speed data transmission is required. In the optical fiber communication system, dense wavelength division multiplexing (DWDM) can significantly improve its transmission capacity, and the dense wavelength division multiplexing optical communication system is the most promising technology at present. The all-optical wavelength converter is one of the key performance devices of the dense wavelength d...

AI Technical Summary

Problems solved by technology

[0016] However, the existing all-optical wavelength converters based on the cascaded sum frequency and difference frequency (SFG+DFG) type have polarization dependence. When the signal light is input in a polarization state, the intensity of the converted idler light output at the end will follow the polarization of the signal light. The direction changes, so the wavelength conversion efficiency is low in some wavelength ranges

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