Tunable laser source

摘要

A tunable laser source that stably outputs high-output light with reduced spontaneous emission light is to be realized. This invention is an improvement of a tunable laser source of external resonator type. This apparatus comprises a wavelength selecting unit for selecting a wavelength of incident light and emitting the light of the selected wavelength, an optical amplifier unit for making light incident on the wavelength selecting unit from one end, and a mirror for reflecting light from the other end of the optical amplifier unit directly to the wavelength selecting unit. The wavelength selecting unit feeds the light from the one end of the optical amplifier unit back to the optical amplifier unit and emits the light from the mirror as output light.