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

点击翻译按钮获取中文摘要

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