METHOD FOR DRIVING VARIABLE WAVELENGTH SEMICONDUCTOR LASER AND VARIABLE WAVELENGTH LIGHT SOURCE DEVICE

摘要

PROBLEM TO BE SOLVED: To suppress the wavelength instability of a variable wavelength semiconductor laser, caused by the hopping of an oscillation axial mode which occurs when the single axial mode laser oscillation wavelength of the semiconductor laser is switched. SOLUTION: When the oscillation mode of a variable wavelength semiconductor laser, having an active region and a wavelength control region is switched to a single axial mode laser oscillation wavelengthλ2 from a single axial mode laser oscillation wavelengthλ1, a waveform control current (λ-Control) is switched to I2 from I1. In the moments before and after the switching is performed, the current flowing to the active region (active) is made smaller than all threshold currents ITH in the oscillation axial mode which exist between the wavelengths, so as to stop the single axial mode laser oscillation of the semiconductor laser by at least a period of time longer than the lives of carriers in the wavelength control region.