Patent ID: 8817829

Claim:
An apparatus for generating a single-polarization mode-locked laser, comprising: a pump laser generator configured to generate a pump laser having a predetermined wavelength; a gain controller formed of an optical fiber whose core is doped with a gain material; a lens unit including a first lens configured to generate parallel light by shifting a path of laser light output from one end of the optical fiber constituting the gain controller, and a second lens configured to focus the parallel light passed through the first lens on a certain area by shifting a path of the parallel light; a polarization controller formed of a quarter-wave plate (QWP) disposed between the first lens and the second lens, and configured to control polarization of the laser light by adjusting an angle thereof with respect to a high-speed axis or low-speed axis of the optical fiber constituting the gain controller; a saturable absorber configured to saturably absorb and reflect the laser light passed through the second lens; a resonance controller formed of a single-mode fiber (SMF), and configured to adjust a resonance length; an output coupler (OC) in which a Bragg grating is formed from one end toward the other end, and configured to output mode-locked laser light; and a pump light coupler connected between the gain controller and the resonance controller or between the resonance controller and the OC, and configured to receive and provide the pump laser output from the pump laser generator toward the saturable absorber, or provide the mode-locked laser light to the OC, wherein at least one of a focal length of the second lens, power of the pump laser output from the pump laser generator, and reflectivity of the OC is adjusted to set fluence, which is defined as energy density per unit area of the laser light incident on the saturable absorber, to be greater than reference fluence, which is energy density per unit area of the laser light incident on the saturable absorber when reflectivity of the saturable absorber is a maximum.