Highly efficient intracavity frequency doubling 532-nm laser based on the gray tracking resistance KTP crystal

Based on the gray tracking resistance (GTR) KTP crystals, the performance of a high efficient and compact intracavity frequency doubling 532 nm laser was investigated. The gray tracking test indicated that the KTP used in our experiment had good resistance to the gray tracking. The absorption coefficient of this GTR-KTP at 1064 and 532 nm were measure to be 5 × 10⁻³%/cm and 0.2%/cm, respectively. The maximum average output power of 40.6 W at 532 nm was obtained at the repetition frequency of 10 kHz for the 10 mm long GTR-KTP, which corresponded to 22.6% pump-to-green conversion efficiency. The effective conversion efficiency from the Q-switched 1064 nm to the green power at 10 kHz repetition rate was as high as 86.4%.