Efficient near diffraction limited blue light source by sum-frequency mixing of a BAL and a solid-state laser

Sum-frequency mixing of an 808 nm broad area laser (BAL) with a build-in grating structure for spectral control and a 1064 nm solid-state laser is experimentally investigated. The spectrally improved 20 mu m wide BAL can deliver up to 700 mW of output power with an M-2 of 1.4 and 5.3 in the fast and slow axis of the diode, respectively. The BAL output beam is single-passed through a periodically poled KTiOPO4 (PPKTP) crystal placed in an intra-cavity beam waist of a 1064 nm Nd:YVO4 laser, resulting in 100 mW of sum-frequency generated blue output power. This corresponds to a power conversion efficiency of 15%. The near diffraction limited blue output beam is measured to have an M-2 of 1.2 and 1.7 in the directions corresponding to the fast and slow axis of the BAL diode, respectively.