Theoretical and experimental researches on the walk-off compensation of an intracavity doubling red laser using a twin-BIBO-crystal

We theoretically and experimentally researched on an intracavity frequency doubling red laser with walk-off compensation of bismuth borate (BIBO) for the first time, to the best of our knowledge. Through theoretical investigations, we described in detail the spatial walk-off characteristics of a BIBO crystal and discussed quantitatively the influence of different arrangements of a twin-BIBO-crystal on the output power of a second harmonic wave. Furthermore, the progress of walk-off compensation was revealed with the arrangement having the second BIBO 180 degrees rotated along extraordinary axis. Experimentally, we found that the maximum average output power with walk-off compensation has been improved by 1.2 times compared to the uncompensated case, and the corresponding intensity profile restored from an oblique ellipse to an approximate circle. (C) 2021 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement