Drastic thermal effects reduction through distributed face cooling in a high power giant-pulse tiny laser

Shape design of sapphire/Nd3+:YAG based distributed face cooling (DFC) chip is reported with reduction of thermal effects as compared with those from a conventional Nd3+:YAG chip. The CW diode laser pumped round-trip cavity loss was 0.51% from a 9-disk bonded DFC chip, which was close to the theoretically calculated total Fresnel reflection loss of 0.2% from 8 Sapphire/Nd3+:YAG interfaces. The depolarization ratio from an 8-disk bonded DFC chip was 40 times lower than that from YAG/Nd3+:YAG chip. The DFC chip underwent no crack at pump power of 86 W while Nd3+:YAG single chip suffered crystal crack under pump power around 54 W. Over megawatt peak power from DFC tiny integrated laser is demonstrated at 1 kHz with 3-pulse burst modes. It is concluded that DFC structure could relieve thermal effects as expected.