| 摘要 |
PROBLEM TO BE SOLVED: To control a wavelength by one band-pass filter and a photoelectric conversion element by detecting the wavelength components of two waves from a plurality of wavelength in an optical band-pass filter and controlling respective optical transmission circuits by an error with a reference voltage. SOLUTION: The light output of the optical transmission circuits 1 and 2 provided with different oscillation wavelengths is multiplexed in a multiplexer 3 and demultiplexed to an optical transmission line 19 and the optical band-pass filters 5 and 6 by a demultiplexer 4. Thereafter, each light output is voltage- converted in the photoelectric conversion elements 7 and 8 and I/V converters 9 and 10 and inputted to operational amplifiers 11 and 12. In this case, the operational amplifier 11 compares it with the reference voltage and inputs error signals 16 to a wavelength control circuit 18. Similarly, the operation amplifier 12 subtracts the output of the I/V converter 9 and further, comparison with the reference voltage 15 is performed in the operational amplifier 13 and the error signals 17 are inputted to the wavelength control circuit 18. In this case, the optical transmission circuits 1 and 2 are controlled so as to turn the respective error signals 16 and 17 to '0'. Thus, the wavelength is controlled by using one band-pass filter and the photoelectric conversion element. |
