| 摘要 |
PURPOSE:To reduce the propagation loss of an optical beam, by changing the heating temperature of an electric heating unit to change the refractive index of a thin film optical waveguide near an exit end face and deflecting the optical beam in the direction vertical to the surface of the thin film optical waveguide. CONSTITUTION:When comb-shaped electrodes 3 are driven with a certain frequency (f), surface acoustic waves SAW of a wavelength are generated on a thin film optical waveguide 2, and the refracive index is changed at a periodic pitch in the optical waveguide 2, and an optical beam P1 of the wavelength which is incident at an angle theta to the wave surface becomes a Bragg-diffracted optical beam P2 reflected by the wave surface if the condition of an expressionIis satisfied. When the driving frequency (f) for comb-shaped electrodes 3 is changed to f+ or -DELTAf, the advance direction of the optical beam P2 is changed in a range of an angle DELTAtheta. That is, the oscillation frequency of a high frequency oscillator 7 is changed continuously in a certain range to change the advance direction of the optical beam P2 continuously. |
