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消偏器是光纤传感器、光放大器等偏振敏感性光学系统中的关键器件,用于减小输入光的偏振度(DOP)。设计了一种与入射线偏振光振动方向无关的低偏振度消偏器,该器件中利用人为的偏振相关延迟代替了保偏光纤的双折射,并在偏振相关型消偏器前增加了一个1/4波片,从而对任意方向振动的线偏振光具有相同的消偏能力,结构紧凑。对消偏性能随波片阶数、入射光中心波长和振动方向的变化作了数值计算。实验中采用半峰全宽为0．13 nm的光源,入射线偏振光在任意方向振动时,输出光偏振度小于2．6%,消偏器的插入损耗为0．6 dB,损耗起伏小于0．11 dB。实验和数值计算结果表明,该消偏器具有低偏振度、低插入损耗和适合于宽光谱应用的优点。
Depolarizers are the key components in polarization-sensitive optical systems such as fiber optic sensors, optical amplifiers and the like to reduce the degree of polarization (DOP) of the input light. A low-polarization depolarizer is designed which is independent of the direction of the incident linearly polarized light. In this device, the birefringence of the polarization-maintaining fiber is replaced by a human-induced polarization-dependent delay, and an additional one is added before the polarization-dependent depolarizer 1/4 wave plate, which has the same depolarization capability to linearly polarized light vibrating in any direction, and has a compact structure. The depolarization performance is numerically calculated according to the order of the wave plate, the center wavelength of incident light and the vibration direction. When the incident linearly polarized light is vibrated in any direction, the polarization degree of the output light is less than 2.6%, the insertion loss of the depolarizer is 0.6 dB, the loss undulation is less than 0.11 dB. Experimental and numerical results show that the depolarizer has the advantages of low polarization, low insertion loss and suitable for wide spectrum applications.