Optical noise of stabilized high-power single frequency optically pumped semiconductor laser.

We present a study of an actively stabilized optically pumped semiconductor laser operating single frequency at a wavelength of 1015 nm. In free running operation, the laser exhibits a single frequency output power of 15 W with a linewidth of 995 kHz for a sampling time of 1 s. The intensity and the frequency of the laser were independently stabilized to reach a laser linewidth of only 4 kHz for the same sampling time. To identify and reduce the different sources of noise, the relative intensity noise and frequency noise spectral density are investigated under various conditions.