| 摘要 |
The output light of a variable-wavelength light source 101 is brought to incidence on an optical resonator 103 having a periodic transmitting characteristic, and the transmitted light is detected by an optical intensity detector 105 and, having the difference from a reference level as the error signal, fed back by an operational amplifier 106 to the variable-wavelength light source 101. Therefore the output light frequency of the variable-wavelength light source 101 is stabilized at the shoulder of the peak of the transmitting characteristic (the point where the transmittance varies) of the optical resonator 103. Wavelength switching is accomplished by selecting one out of two variable current sources built into a wavelength control circuit 108. This variable current source switching forcibly shifts the stabilization point to the shoulder of the peak of another transmittance of the optical resonator 103. Upon supply of a wavelength designation signal 100-2 from outside, the output current value of the variable current source which is at present in a stand-by state is set at a value corresponding to the designated wavelength. <IMAGE> |
