Broadband second-harmonic-generation in GdCOB crystals

Broadband second-harmonic-generation (SHG) in GdCOB crystals was demonstrated for the first time. Theoretical calculation and experiments for the type-I frequency doubling of GdCOB crystal was performed. The result revealed that the spectral retracing point of phase-matching angle was at around 1.65 µm. For broadband fundamental laser source tuning in the range of 1.55-1.7 µm, efficient SHG was realized, the highest conversion efficiency was 56%, and the output bandwidth reached 16 nm.