CPC H01S 3/131 (2013.01) [H01S 3/08009 (2013.01); H01S 3/107 (2013.01); H01S 3/10007 (2013.01); H01S 3/10069 (2013.01); H01S 3/136 (2013.01); H01S 5/0617 (2013.01)] | 3 Claims |
1. A swept light source configured to output a beam having a continuously changing lasing wavelength, the swept light source comprising:
a laser resonator including
a gain medium configured to amplify a beam,
means for changing a lasing wavelength, and
means for changing an optical gain of the gain medium;
wavelength control means configured to control the means for changing a lasing wavelength by using a wavelength control signal and sweep the lasing wavelength; and
optical gain control means configured to set the means for changing an optical gain so that the optical gain in the laser resonator has an optical gain value slightly higher than an optical gain in a state of a lasing threshold over an entire wavelength range of a wavelength sweep and to detect an output light level from the laser resonator, generate an optical gain control signal based on the detected output light level so that the output light level has a predetermined output light level value, and control the means for changing an optical gain by using the optical gain control signal,
wherein the optical gain control means performs temporally discrete control in conjunction with a wavelength sweep by using a bisection method of gradually reducing by half a change amount of the optical gain with respect to a difference between the output light level and the predetermined output light level.
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