High efficiency frequency doubling with a passive enhancement cavity

Abstract

Highly efficient frequency doubling of a continuous-wave Yb-doped fiber laser with a passively-locked enhancement cavity is achieved. The increase in efficiency is a result of improved transverse mode matching between the fiber and doubling cavities, which is enabled by an alignment method presented here. An optical conversion efficiency as high as 36.8% from a launched 976 nm diode pump to a 532 nm green laser is obtained. The maximum 532 nm output is 24.5 W, which is limited by the onset of parasitic oscillations in the fiber laser.

Realizing high efficiency 532 nm laser by optimizing the mode- and impedance-matching

“…The pulse pump increases the peak pump intensity and the waveguide ensures a uniform transverse size in the whole interaction length, owing to its two-dimensional spatial confinement [10][11][12][13]. For the SHG of continuous-wave light, via the bulk crystal, cavity enhancement of the frequency-doubling process becomes a general technique, which is equivalent to increasing the crystal length or pump intensity [14][15][16][17][18][19][20][21][22]. To completely characterize the external cavity SHG, we must additionally consider the cavity influence on the basis of the B-K model.…”