Light-light control type communication devices using optical fiber micro-machining and photochromism phenomenon

首先，将光致变色材料（二乙烯和Optodyne UV-1100的混合物，质量比为1:9）与薄单模光纤一起使用，作为光-光控制的可变衰减器。光纤上的薄化区长度为45 mm，直径为18 μm。来自卤素灯（250w）的光被聚焦在纤薄光纤的输入端。薄化区被厚度约500 μm的光致变色材料包裹，系统温度保持在25℃。衰减器的插入损耗由透射光谱确定，当光致变色材料用紫外光照射时，在光纤输出端使用光谱分析仪测量。辐照14min后，插入损失降低约9.5 dB。然后根据实验结果估计了光致变色材料的折射率变化。在变细的光纤（长度为20 mm，直径为18 μm）周围再加一层甘油，当温度升高60℃时，插入损耗降低约15 dB，导致甘油折射率变化0.0132。假设插入损耗与变薄区域的长度成正比，可估计光致变色材料的折射率变化约为0.005。接下来，研究了一个类似的系统作为可调谐波长滤波器。在这种情况下，使用了一种细长的光栅光纤（10/120 μm芯/包层直径，1550 nm光栅波长，10 mm光栅区域）。包括光栅在内的薄化区域长度为45 mm，直径为20 μm。来自卤素灯（250w）的光被聚焦在变细的光纤的输入端。用厚度约为200 μm的光致变色材料包裹薄层，用恒温水浴保持温度在80℃恒定。为了使光致变色材料的折射率降低到接近包层的折射率（1.458），需要较高的温度。用紫外光照射光致变色材料，在光纤输出端用光谱分析仪测量透射光谱，确定中心反射波长，辐照10 min后中心反射波长减小约0.2 nm。如果采用折射率较低的聚合物作为光致变色材料，可以预期更大的波长位移，正如紫外线照射开始时的高位移率所表明的那样。少

First, the photochromic material (A mixture of diarylethene and Optodyne UV-1100 at a mass ratio of 1:9) was applied for use with a thinned single-mode fiber as a variable attenuator for light-light control. The length and diameter of the thinned region on the fiber was 45 mm and 18 μm, respectively. Light from a halogen lamp (250 W) was focused on the input side of the thinned optical fiber. The thinned region was surrounded by photochromic material at a thickness of about 500 μm, and the temperature of the system was maintained at 25 ℃. The insertion loss of the attenuator was determined from the transmitted light spectrum, as measured using an optical spectrum analyzer at the output end of the fiber while the photochromic material was irradiated with UV light. The insertion loss decreased by about 9.5 dB after irradiation for 14 min. The refractive index change of the photochromic material was then estimated from the experimental results. When glycerine was used as an additional cla … More dding layer around the thinned optical fiber (length : 20 mm, diameter: 18 μm), the insertion loss decreased by about 15 dB with a temperature increase of 60 ℃, resulting in a refractive index change of 0.0132 in glycerine. Assuming that the insertion loss is proportional to the length of the thinned region, the refractive index change of the photochromic material can be estimated to be about 0.005. Next, a similar system was examined for use as a tunable wavelength filter. In this case, a thinned grating fiber (10/120 μm core/cladding diameter, 1550 nm grating wavelength, 10 mm grating region) was used. The length and diameter of the thinned region including the grating was 45 mm and 20 μm, respectively. Light from a halogen lamp (250 W) was focused on the input end of the thinned optical fiber. The thinned region was surrounded by photochromic material at a thickness of about 200 μm, and the temperature was maintained constant at 80 ℃ using a thermostated water bath. The high temperature was required to reduce the refractive index of the photochromic material to close to that of the cladding (1.458). The center reflection wavelength was determined from the transmitted light spectrum measured using an optical spectrum analyzer at the output end of the fiber while the photochromic material was irradiated with UV light The center reflection wavelength decreased by about 0.2 nm after irradiation for 10 min. A larger wavelength shift can be expected if a polymer with a lower refractive index is adopted for the photochromic material, as suggested by the high shift rate at the beginning of UV irradiation. Less