OPTICAL FIBER FILTER AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an optical fiber filter of a narrow band with low reflection. SOLUTION: The optical fiber filter 1 has a grating 30 functioning as a filter in the core 10. The grating has a structure of periodically arranged planes 32 having an equal refractive index inclined with respect to the axial line 5 of the core. The inclined grating is formed in the region having <0.1% relative refractive index difference. A narrow band can be obtained by decreasing the inclination of the grating. The reflected light on the inclined grating propagates in the direction out of the axial line of the core. Since the relative refractive index difference is as small as <0.1%, the reflected light is easily emitted into the clad. Therefore, reflection can be sufficiently suppressed even when the inclination of the grating is small.