| 摘要 |
PURPOSE:To suppress the seleced center wavelength shift of a filter itself due to the variance of the ambient temperature with respect to the filter using a diffraction grating. CONSTITUTION:A diffraction grating 3 is rotated in the direction of an arrow in accordance with the rise of the ambient temperature by a temperature compensating mechanism part 4 arranged in the diffraction grating 3. When the temperature rises by deltaT, the angle of rotation of the temperature compensating mechanism part 4 is changed by deltatheta to cancel the shift of the selected center wavelength to the longer wavelength side due to the rise of the temperature, and the angle of incidence from an input/output fiber 1 to the diffraction grating 3 through a lens 2 is reduced, and the selected center wavelength of light which is subjeted to wavelength dispersion and is coupled to the input/output fiber 1 through the lens 2 again is lambdao independently of the rise of the temperature. |
