Efficient intracavity frequency doubling from a diffusive reflector-type diode side-pumped Nd:YAG laser using a KTP crystal

Nd:YAG lasers have been popularly used for such industrial applications as the marking, drilling, and cutting. To process materials more precisely with good quality, the second harmonic of a Nd:YAG laser is preferable. After the technology of continuous-wave or quasi-CW laser diode had developed the laser diode (LD) became an alternative pumping source of solid-state lasers. Because the lifetime of LD exceeds about 10,000 hours and its wavelength can be adjusted to the absorption peak of the laser crystal, compact diode-pumped solid-state lasers (DPSSL) can be realized. Recently, DPSSL rapidly replaced the lamp-pumped solid-state laser as the price of high-power LD decreases for the improvement of cooling and manufacturing technology. Compared with the end-pumping scheme, the side-pumping scheme was more suitable for high-power lasers. Among the various types of reflector for side-pumping, the diffusive reflector proved to be an efficient one for enhancing the absorption efficiency with uniform distribution of absorbed power in the rod. More than 50% of slope efficiency were reported in the diffusive reflector type diode-side pumped Nd:YAG laser. In the study, we investigated the intracavity frequency doubling with a KTP in a folded resonator.