| 摘要 |
PROBLEM TO BE SOLVED: To provide the highly accurate optical PLL circuit with simple constitution. SOLUTION: Reception optical signals composed of the signal light pulses of a repetition frequency N×f0 are modulated by the reference signals of f0+Δf from a reference oscillator 102 in an optical intensity modulation circuit 103, an AND processing is performed and difference frequency information N×Δf is generated. The signals are electrically converted in a photodetector, only low frequency components N×Δf are extracted by a narrow-band filter and frequency-divided into 1/N by a frequency divider circuit 106 and the low frequency components Δf are obtained. In the meantime, the reference signals and the output (f) of a voltage controlled oscillator 110 are inputted to a multiplier 107 and the difference frequency components (f0+Δf)-f of both signals are generated. The low frequency components Δf and the difference frequency components (f+Δf)-f are compared in a phase comparator circuit 109 and the voltage controlled oscillator 110 is controlled so as to turn the phase difference to zero. |
