摘要 |
In a tunable filter for launching incident light from an input side optical fiber into a diffraction grating through a condenser lens and emitting emission light from the diffraction grating through the condenser lens and outputting output light of a selected wavelength through an output side optical fiber, one optical fiber common to input and output is provided between the input side optical fiber and the output side optical fiber and the condenser lens, and also optical circulator member is provided between the input side optical fiber and the output side optical fiber and the one common optical fiber.
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