| 摘要 |
PROBLEM TO BE SOLVED: To provide a low-cost wavelength holding circuit, capable of holding the oscillation wavelength of a light source, without having to depend on the intensity change of an output light of the light source. SOLUTION: The low-cost wavelength holding circuit comprises an optical branching unit 4 for branching an input light from a wavelength variable light source 12, and an optical frequency discriminator 5 which can output an intensity (p) of the input light and the intensity of the transmitted light of an optical branching element 3. The holding circuit further comprises an adder 8 for adding a wavelength setting signal and a temperature compensating signal, and a multiplier 9 for multiplying the result of the adder 8 by the intensity (p) of the input light to subtract an intensity signal of the transmitted light of the element 3 from the signal output from the multiplier 9, to generate an error signal which is to be given to the light source 12. |
