All-optical photo-thermal polarization modulator and system based on micro-nano optical fiber asymmetric mode field

Abstract

The invention discloses an all-optical photo-thermal polarization modulator and system based on a micro-nano optical fiber asymmetric mode field, and the modulator comprises an optical fiber gas chamber which is used for receiving signal light and pump light; the optical fiber air chamber comprises a sealed inner cavity and a micro-nano optical fiber located in the sealed inner cavity, and the outer part of the micro-nano optical fiber is filled with light absorptive gas; the micro-nano optical fiber has a fundamental mode field, and the light intensity of an evanescent field of the fundamental mode field on the cross section of the micro-nano optical fiber in the first angle direction is larger than the light intensity in the second angle direction. The light absorptive gas in the first angle direction and the light absorptive gas in the second angle direction have a temperature difference through a photothermal effect generated when the light absorptive gas absorbs the pump light, so that a birefringence effect is formed, and the fast axis and the slow axis correspond to the first angle direction and the second angle direction respectively; the linear polarization angle of the signal light is changed by adjusting the phase difference between the fast axis and the slow axis. The problem that polarization modulation of incident light in any polarization state is difficult to achieve due to the fact that the main axis direction of the crystal is fixed in the prior art is solved. 本申请公开了一种基于微纳光纤非对称模场的全光光热偏振调制器及系统，包括光纤气室，其用于接收信号光、以及泵浦光；光纤气室包括密封内腔，以及位于密封内腔中的微纳光纤，微纳光纤的外部填充有光吸收性气体；微纳光纤具有基模模场，其倏逝场在微纳光纤横截面上沿第一角度方向上的光强大于沿第二角度方向上的光强；通过光吸收性气体吸收泵浦光所产生的光热效应而使第一角度方向和第二角度方向的光吸收性气体具有温度差，以形成双折射效应，且快轴和慢轴分别对应第一角度方向和第二角度方向；信号光通过快轴和慢轴之间的相位差的调整而改变线偏振角度。解决了现有技术中晶体主轴方向固定而导致难以实现对任意偏振态的入射光进行偏振调制的问题。