OPTICAL UNIT WITH OPTICAL FIBER DIFFRACTION GRATING

摘要

PROBLEM TO BE SOLVED: To restrain a Bragg wave-length from being affected in a diffraction grating, and to protect an optical fiber part where the diffraction grating is formed and a base material where an optical fiber is fixed. SOLUTION: A temperature compensating device 1 is composed of a cylindrical member 2 formed of quartz glass, and an Al bracket 3. An optical fiber 4 with a diffraction grating 6 formed is fixed to the Al bracket 3 with an adhesive 5. The temperature compensating device 1 is provided inside a stainless steel casing 7. The casing 7 is composed of wall parts 7a extended to the optical axis direction of the optical fiber 4 and end caps provided in both end parts of the wall parts 7a. Protrusions 8 projected inside the casing 7 are formed in the wall parts 7a. A space between the protrusions 8 in the radial direction of the optical fiber 4 is set to be equal to a length in the radial direction of the fiber 4 of the cylindrical member 2 of the device 1.