PURPOSE: To eliminate the influence of resonance and expand the band of a sensor by forming parallel grooves which have finite depth in the advancing direction of light in a crystal surface crossing the advancing direction of the light at right angles.
CONSTITUTION: Light incident to an optical fiber 1 is passed through a rod lens 2, a polarizer 3, and a half-wavelength plate 4 to reach a bismuth silicon oxide (BSO) element 5 formed by making parallel grooves 9 in a BSO plate of[width (w)× length (l)× depth (d)]and then dividing the whole into (n). This light changes in the state of polarization according to the level of a voltage applied from an input voltage source 7 to the BSO element 5 through an electrode, so the state of polarization is detected to detect the level of an input voltage to be detected. Consequently, while (n) is increased to decrease width T, a resonance frequency nearly depends only upon T and is increased high without reference to (l), and the transmission loss of light is reduced by decreasing groove width (t) until it causes no problem substantially.
KUHARA MIKI
TATSUMI MASAMI
HAMAZAKI YUUJI
