To provide a light frequency stabilizing light source having high accuracy and stability in light frequency.
An optical branch 8 branches output light from a local light emission source 7 into two components. A photodetector 2 detects a beat signal to which a light frequency difference between the output light from the light source 7 and reference pulse light is superposed and a rectifier 3 rectifies the beat signal. A time measuring circuit 4 measures time at which the beat signal is obtained. A frequency measuring circuit 5 measures beat frequency. A CPU 6 outputs a deviation between the light frequency of the output beam and objective light frequency. A Fabry-Perot etalon transmissivity detection circuit 11 outputs an electric signal corresponding to the light frequency of output light from an optical branch 9. A control circuit 12 controls the light frequency of the light source 7 so that the electric signal always corresponds to the objective light frequency. A Fabry-Perot etalon control circuit 10 corrects relation between the light frequency of input light to the circuit 11 and an output electric signal.
TAKATSU TATSUHIKO
SATO NAOTO
AIDA KAZUO
MASUDA KOJI
NIPPON TELEGRAPH & TELEPHONE