| 摘要 |
PROBLEM TO BE SOLVED: To provide a so-called hitless wavelength variable filter module which switches wavelengths (channels) to the desired wavelength without affecting the irrelevant wavelengths (channels) during switching of the wavelengths (channels), and further to provide a method of expanding the pass-band width of the light beam transmitted through the wavelength variable filter. SOLUTION: A reflecting mirror is installed adjacently to the wavelength variable filter and a light beam is moved from the first channel on the wavelength variable filter directly to the reflecting mirror and then the light beam is moved from the reflecting mirror to the wavelength variable filter of the desired channel. Further, the module includes a plurality of the wavelength variable filters varying in wavelength regions and the respective wavelength variable filters share the reflecting mirror, thereby decreasing the wavelength variable areas of the respective wavelength variable filters. The method of expanding the pass-band of the light beams transmitted through the filters by lowering the rates of the thin film thickness inclinations of the respective wavelength variable filters is provided. COPYRIGHT: (C)2004,JPO
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