High power 404 nm source based on second harmonic generation in PPKTP of a tapered external feedback diode laser

We present results on a 404 nm laser system based on second harmonic generation in a new compact external cavity configuration. We obtain a stable 318 mW cw diffraction limited output from the system with a mode-matched pump power of 630 mW. We observe up to 620 mW SHG, when the cavity is operating in scanning mode. The pump source is an external cavity grating feedback tapered diode laser operating at 808 nm. We find that thermal effects in the nonlinear crystal severely limit the efficiency of the setup with high input powers.