PURPOSE: To lead out a frequency-modulated light wave as a light-intensity- modulated light wave by utilizing the rotation of the plane of polarization of a light wave by nonlinear effect.
CONSTITUTION: The output light 14 of a pigment laser 9 excited by a pigment laser exciting light source 8 is split by a beam splitter 10 into signal light 15 and local oscillation light 16. Then, the signal light 15 is passed through a frequency converter 12 and then the signal light 15 and local oscillation light 16 are put together by using a mirror 11 and a beam splitter 10 to obtain input light 6. An attenuator 17 is put in the optical path of the local oscillation light 16 and so adjusted as to equalize the light intensity of the oscillation light 15 to that of the local oscillation light 16 at the time of the light mixing. At this time, the input light intensity is modulated with the difference frequency between the signal light 15 and local oscillation light 16, so output light modulated with the same frequency as the frequency of frequency modulation imposed upon the signal light 15 is obtained. Thus, the frequency-modulated light signal is led out as the intensity-modulated light signal completely optically.
FUKUZAWA TADASHI
MATSUMURA HIROYOSHI
