WAVELENGTH-SWEPT LIGHT SOURCE, METHOD FOR GENERATING DRIVE DATA FOR WAVELENGTH-SWEPT LIGHT SOURCE, AND OPTICAL DEFLECTOR

摘要

In an SS-OCT device, the strength of an interference signal increases as a coherence length of a beam from a swept light source becomes long. A conventional swept light source, which performs temporally constant current injection into a gain medium, cannot keep a coherence length long over an entire wavelength range in which a wavelength sweep is carried out. There is a problem that PSF strength having a direct influence on the quality of an output image of the SS-OCT device decreases. A swept light source of the present invention keeps a coherence length of an output beam long over an entire sweep wavelength range. A gain of a gain medium is changed with time in response to a wavelength sweep and the coherence length is kept maximum. The gain of the gain medium is kept close to a lasing threshold and an unsaturated gain range of the gain medium is narrowed over the entire sweep wavelength range. An SOA current waveform data acquiring method of driving while keeping the coherence length long, a novel coherence length measuring method, and an optical deflector suitable for the swept light source are also disclosed.