宽带光纤λ/4波片的温度特性

Temperature characteristics of broad-band fiber-optic λ/4 waveplate

宽带光纤λ/4波片是一种特殊的变速旋转型双折射光纤。当其旋转速度由小到大逐渐增加时,可将输入的线偏振光转换为圆偏振光,同时具有理想的偏振变换带宽。结合全光纤电流互感器的光路模型,分析了宽带光纤λ/4波片的特性对互感器标度因数稳定性的影响。通过在邦加球上的轨迹,对宽带光纤波片快转端的本征态及两正交本征态间的耦合系数进行了实验研究,测量了其随温度的变化。实验结果表明,当波片转速变化曲线满足一定条件时,宽带光纤λ/4波片的温度效应对电流互感器标度因数稳定性的影响小于0.2%,远小于窄带光纤λ/4波片的影响。利用宽带光纤λ/4波片可有效提高光纤电流互感器系统的温度稳定性。

The broad-band fiber-opticλ/4waveplate is a special birefringent fiber with a slowly varying spin rate.When the spin rate gradually increases,it could transform the linearly polarized light into the circularly polarized light,covering a broad frequency range.Based on the loop model,the influence of the broad-band fiber-opticλ/4waveplate on the scale factor stability of the all-fiber optic current sensor was analyzed.The eigen-modes of the fast-spun end and the coupling coefficient between the two orthogonal eigen-modes,along with the temperature characteristics,were measured using the trajectories on the Poincare sphere.Experimental results show that when the spin rate meets certain conditions,the influence of the broad-band fiber-opticλ/4waveplate on the scale factor stability induced by the temperature variation is less than0.2%,much weaker than that of the narrow-band fiber-opticλ/4waveplate.The temperature stability of the all-fiber optic current sensor could be improved by using broad-band fiber-opticλ/4waveplate.