PURPOSE: To expand the measuring frequency range of a light-applying voltage field sensor by increase in resonance frequency by laminating crystal plates which are made short in the length of only the specific sides in the direction at a right angle to the advancing direction of light.
CONSTITUTION: The light incident to an optical fiber 1 passes through a rod lens 2, a polarizer 3, and a 1/4 wavelength plate 4, and is made incident to a BSO element 5 having construction 9 laminated with n-sheets of bismuth silicon oxide (BSO) of width w × length l × depth b. Since the light changes in the state of polarization according to the magnitude of the voltage applied to the BSO element 5 via an electrode from an input voltage source 7, the magnitude of the voltage to be detected is detected by knowing the state of the polarization thereof. Then the respective BSO pieces show the high resonance frequencies determined roughly by the w, thus providing higher frequencies. In addition, the wider incident area for light can be taken, whereby the degradation in sensitivity owing to the degradation in S/N is prevented.
TADA KOUJI
TATSUMI MASAMI
HAMAZAKI YUUJI
