根据光纤包层中的倏逝场机制,将具有热光效应的聚合物材料直接覆盖在侧边抛磨光纤上,进行了全光纤热光型可变光衰减器(VOA)的研究。根据理论分析,确定了在侧边抛磨光纤的抛磨区上覆盖材料的折射率与纤芯中光衰减量之间的关系,为选择适当折射率的热光材料提供依据。设计适当的侧边抛磨区,利用先进的轮式侧边抛磨技术,制备了侧边抛磨光纤,以达到最佳可变光衰减效果。采用螺绕电极和优化封装,制作出性能优良的全光纤热光型可变光衰减器。性能测试表明,器件插入损耗小于0.1 dB,衰减范围为0～80 dB,偏振相关损耗小于0.02 dB,背向反射大于70 dB。该方法制作的全光纤热光型可变光衰减器具有可用电驱动调控、可靠性高等优点。

Based on evanescent wave theory, the all fiber thermooptical variable optical attenuator (VOA) made of side-polished fiber overlaid with thermooptical polymer material was studied. The relation between the refractive index of overlaid polymer material on the polished section of side-polished fiber and optical loss in the core was derived to help select thermooptical material with suitable refractive index for VOA. Proper side-polished section was designed, and advanced wheel side-polished technique was used to fabricate side-polished fibers and achieve an optimal variable loss effect of VOA. An excellent all-fiber thermooptical variable optical attenuator with helical electrode and optimized packing was fabricated. The test result of the all fiber thermooptical VOA showed that it had insertion loss less than 0.1 dB, loss range of 0～80 dB, polarization dependent loss less than 0.02 dB, and back reflection over 70 dB. The all-fiber thermooptical VOA fabricated by this means can be controlled electrically with high reliability.