| 摘要 |
PROBLEM TO BE SOLVED: To embody a variable wavelength filter capable of varying a selected wavelength with a high degree of freedom by utilizing the nonlinear optical effect of optical fiber diffraction gratings and to embody the constitution which is compact and lessens the loss of light power by introducing control light into these diffraction gratings. SOLUTION: The optical fiber diffraction gratings 2 formed by subjecting core parts to refractive index modulation at prescribed periods are connected to the input and output terminals 1b of an optical circulator 1. Further, the outside is provided with a light source 3 and a beam shape shaping optical system 4 in order to make the control light incident on the optical fiber diffraction gratings 2. This beam shape shaping optical system 4 shapes the beam shape of the light emitted from the light source 3 and effectively irradiates the core parts periodically subjected to the refractive index modulation of the optical fiber diffraction gratings 2 with the light. When the core parts of such optical fiber diffraction gratings 2 are irradiated with the control light of high intensity, the nonlinear optical effect arises in the core parts and the refractive index of the core parts may be changed. |
