| 摘要 |
PURPOSE:To make an external oscillating circuit unnecessary and to improve the purity and the stability of a high frequency signal for the oscillation of a surface acoustic wave by generating the high frequency signal for the oscillation of the surface acoustic wave by a positive feedback oscillator consisting of a closed loop including reed screen type electrodes for oscillation and wave reception. CONSTITUTION:Reed screen type electrodes 3a and 3b and an amplifier 5 constitute the closed loop, and the surface acoustic wave is propagated from the reed screen type electrode 3a in directions of arrows 11 and 12 when this closed loop is oscillated. The surface acoustic wave propagated in the direction of the arrow 11 deflects an incident luminous flux 8 of a thin film optical waveguide 2 and is absorbed by an absorbing material 13a. The surface acoustic wave propagated in the direction of the arrow 12 is converted to an electric signal by the reed screed type electrode 3b to become a positive feedback signal for oscillation of the closed loop. Since the oscillation level of the closed loop is approximately equal to the saturation output level of the amplifier 5, the saturation level of the amplifier 5 is set to level matched to a desired value to set the power of the surface acoustic wave oscillated from the reed screen type electrode 3a to this desired value. |
