| 摘要 |
PROBLEM TO BE SOLVED: To improve the wavelength setting accuracy of a variable wavelength LD light source to about±0.01 nm even when the wavelength of the light emitted from the light source is not confirmed, by measuring the wavelength with a wavemeter whenever the wavelength is set. SOLUTION: A variable wavelength LD light source is constituted of an external resonator type LD light source section 1, an optical filter 2 which selects the output light of the section 1 in a single mode, a driving section 3 which changes the transmitting or reflecting wavelength of the filter 2 or the length of the external resonator of the section 1, and a control section 4 which controls the driving section 3 and an LD driving current based on the optical output of the section 1 and the set wavelength of the filter 2. Further, the LD light source is also formed of an optical coupler 5 which branches the output light of the section 1 into two parts as one incident light, a fiber grating 6 which reflects the specific wavelength band of the output light, a first optical branching device 7 to which the reflected light from the grating 6 is made incident through the coupler 5, a first etalon 8 which transmits the output light from a specific wavelength band to a single wavelength, a second optical branching device 10, a second etalon 11 which transmits the output light of while wavelength band on a wavelength axis, and first and second etalon transmittance measuring sections 9 and 12 which respectively transmit the transmittance of the first and the second etalons 8 and 11 to the control section 4.
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