MANUFACTURE OF OPTICAL WAVEGUIDE WITH GRATING

摘要

PROBLEM TO BE SOLVED: To provide an optical waveguide with grating by converging/ irradiating a pulse laser beam and increasing a refractive index of a selection part. SOLUTION: A convergent point F is adjusted in the inside of the optical waveguide W, and the pulse laser beam 2 of a wavelength region of the absorption coefficient 5 cm-1 or below of the optical waveguide W is converged/ irradiated, and a refractive index increase region G is formed on the convergent point F. When the convergence/irradiation of the pulse laser beam 2 is repeated while teletively and intermittently moving the convergent point F in the longitudinal direction in the inside of the optical waveguide W, plural refractive index change regions G are formed in the longitudinal direction of the optical waveguide W. The grating period is adjusted by the relative moving distance of the convergent point F. When the peak power density of the pulse laser beam 2 is changed, the grating that the refractive index change is different at very convergent point F is added also.