GRATING TYPE OPTICAL PARTS AND THEIR PRODUCTION

摘要

PROBLEM TO BE SOLVED: To suppress an increase in transmission loss and to permit easy production at a low cost by forming gratings on one side of a plane of the core of an optical waveguide inclusive of the core. SOLUTION: An optical fiber 1 is subjected to a pressurization hydrogen treatment in its bare fiber part as the treatment of a fore stage for forming the gratings 1c. The optical fiber is irradiated with a laser beam for several minutes to several tens minutes through a face mask from the front surface side of the plane P inclusive of the core 1a by using a light source of an excimer laser of 350 mW and a wavelength 248 nm. As a result, the optical fiber 1 is formed with the gratings 1c periodically changed in its refractive index at a prescribed length along a longitudinal direction within the core 1a. The entire surface of the optical fiber 1 is irradiated with the laser beam for several minutes to several tens minutes without using the face mask from the rear surface side of the plane P inclusive of the core 1a. The gratings 1c periodically changed in its refractive index at the prescribed length along the longitudinal direction are formed on the front surface side of the plane P inclusive of the core 1a.