光纤热极化过程的实时测试研究

通过热极化可以使中心对称的熔石英光纤中产生二阶非线性效应和线性电光效应。为了解各热极化过程参量对热极化产生的线性电光效应的影响，利用全保偏光纤马赫一曾德尔干涉仪构造了一套光纤热极化的实时线性电光效应测试系统，并利用其进行了光纤热极化全过程的监控测试。在线测试了热极化过程的一些参量，例如极化电压、极化时间、以及极化温度等对热极化光纤中产生的线性电光效应的影响。实时测试研究表明，在光纤中施加尽可能高的极化电场将可能在光纤中产生较高的线性电光效应。对侧边抛磨光纤结构的热极化器件，考虑到器件的抗强电场击穿能力，可选用3．o～4．0kV左右的极化直流电压。当施加3．0kV左右的极化电压时，热极化优化时间约为16min，最佳热极化加热温度约为190℃。

In Situ Investigations of Thermal Poling Process of Optical Fibers

Thermal poling of silica optical fibers can produce permanent second-order nonlinear and linear electooptic effect in fused silica fibers. In order to investigate the effects of processing parameters in thermal poling, an in situ testing system used for thermal poling process is constructed with an all polarization maintaining fiber Mach-Zehnder interferometer and is used for the in situ monitoring the thermal poling optical fibers. The effects of processing parameters in thermal poling, such as applied poling voltage, poling duration and ambient temperature, on the linear electrooptic effect created in the optical fiber are investigated. Experiments of the in situ monitoring show that the stronger the electric field in the fiber core is the higher linear electrooptic coefficient created in the fiber core could be. Considering the electrical breakdown of dielectric medium between electrodes for the structure of side polished fiber, the range of voltages of 3～4 kV could be applied during thermal poling. When around 3 kV is applied on the device with side polished fiber, the optimum poling duration is about 16 min and the optimum ambient temperature for thermal poling is about 190 ℃.