Light generation method and light source

摘要

The present invention provides a light generation method and a light source that are preferable in obtaining a single-mode light having high outputs, a small wavelength spectral bandwidth, and a low intensity noise. A white output from a white-light source (1) and having wavelength components over a wide-band in a wavelength spectrum passes through an isolator (2) and is then filtered by a disc-shaped optical filter (3). A transmitted light is input to a semiconductor optical amplifier (5) having its polarization plane regulated by a polarization controller (4). An output from the amplifier (5) passes through an isolator (6) and is then filtered by a disc-shaped optical filter (7) again to generate a single-mode light having a small spectral bandwidth and high outputs. Polarization control by the polarization controller (4) corresponds to control of the polarization plane of a semiconductor laser in the semiconductor optical amplifier (5) so as to obtain a maximum gain from the amplifier (5). This configuration enables a single-mode light having a small spectral bandwidth and high outputs to be easily generated at an arbitrary wavelength.