| 摘要 |
PROBLEM TO BE SOLVED: To provide a tunable filter for causing arbitrarily varying a wavelength of reflected or transmitted light to be arbitrarily varied by varying a grating interval of a diffraction grating to be loaded. SOLUTION: The tunable filter is provided with an optical fiber 20, to which a wavelength division multiplexing optical signal is inputted from one end thereof and which has a part of the cladding 22 ground to a level close to the core 21, a fiber block 30 holding the optical fiber 20 in a bent state retaining the ground part 23 on the outside, a freely deformable diffraction grating block 10, comprising the diffraction grating dividing the wavelength division multiplexing optical signal formed and jointed to the fiber block 30 so as to be jointed to the ground part 23 and a pressing means for outputting an optical signal of a desired wavelength from the other end of the optical fiber 20 by pressing and deforming the diffraction grating block 10 and varying the grating interval of the diffraction grating. |
