Wavelength stabilization of high-power blue laser diodes using large-area femtosecond fiber Bragg gratings.

We report the wavelength stabilization of a high-power blue laser diode operating around 445 nm. This has been achieved by inscribing a second-order multimode fiber Bragg grating (FBG) into the pigtail fiber of the diode using 400 nm femtosecond pulses, the phase-mask technique, and a rotative fiber inscription setup. Compared to the same free-running diode, the thermal drift of the laser emission was reduced by a factor of 2.5 and its spectral linewidth was reduced by a factor of 2.4, while a power penalty of 17.8% was measured at the maximum output power of 36.7 W.