| 摘要 |
PURPOSE:To attain optical heterodyne detection stable in the detecting characteristic by separating a synthesized wave of an input signal and a local oscillating light into two optical beams where polarized planes are orthogonal. CONSTITUTION:An output light 2 of a local oscillator 1 is synthesized with a signal light 6 at an optical wave synthesizer 7 as a circular polarized light at a circular polarized element 3 of a polarized light converting element 3. A synthesized output light 8 is separated into the 1st and the 2nd optical beams 10, 11 having a linearly polarized wave orthogonal with each other by a polarized light separating element 9. Each optical beam is converted into electric signals 14, 15 at the 1st and the 2nd photodetecting sections 12, 13, and inputted to detecting circuits 16, 17. Each detected output is converted into base band signals 18, 19, synthesized at a synthesizer 22 and reduced to a demodulated output 23. Thus, the stable detecting characteristic is attained independently of the polarized state of the signal. |
