外应力对Y波导器件尾纤消光比的影响

本文研究了外应力对Y波导器件尾纤消光比及其温度稳定性的影响机理.在对保偏光纤固定部分进行应力分析的基础上,研究了外应力的大小、方向对于光纤应力双折射及尾纤消光比的影响,并分析了消光比的全温稳定性.结果表明,外应力是影响消光比常温性能及全温稳定性的主要因素.当外应力的方向与光纤固有应力双折射的主轴不重合时,尾纤最大消光比会低于保偏光纤的固有消光比,并且耦合后波导芯片与光纤慢轴之间对轴失准.当温度变化时,外应力的变化将导致消光比随温度的波动.当外应力沿着保偏光纤固有双折射主轴方向时,能够确保尾纤在耦合过程中实现最大的消光比,并保证波导芯片偏振方向与光纤慢轴的严格对准,此时尾纤消光比具有最佳的温度稳定性.对V型槽和U型槽光纤固定块进行了尾纤消光比性能及其温度稳定性的比较分析,试验验证表明,V型槽方案相对于难以保证外应力方向与光纤慢轴重合的U型槽固定块设计方案而言,可以有效改善消光比性能及其全温温度稳定性.

Effects of External Stress Applied to PM Fiber-pigtail on Extinction Ratio of a Y-branch Multi-functional Integrated Optical Device

Effects of external stress applied to polarization-maintaining(PM) fiber pigtail of a Y-branch multi-functional integrated optical device on extinction ratio as well as its temperature stability are researched.Based on the analysis of stress on the fiber,expression of extinction ratio as a function of the magnitude and direction of the stress is deduced,and the temperature stability of extinction ratio is discussed.Results show that the external stress is the main factor which affects extinction ratio and its stability.When the direction of stress is at an angle from the birefringent axes of a free PM fiber,the maximum extinction ratio achieves during fiber-chip coupling is smaller than that of a free fiber.As a result,the polarizing direction of the chip and the slow axis of the fiber will be mis-aligned.The change of the stress in magnitude and direction caused by temperature results in the fluctuation of the extinction ratio.While the stress is along the birefringent axes of the fiber,it has no effect on extinction ratio,and the polarizing direction of the chip and the slow axis of the fiber can be precisely aligned.Fiber pigtails fixed with a V-groove and with a U-groove are analyzed in comparison,and test results show that a fixing block with a V-groove can improve extinction ratio and its stability effectively.