Novel end-pumping method for stable and compact microchip laser

Summary form only given. Passively Q-switched microchip lasers are very attractive for various applications because of their sub-nanosecond pulse width, simple and rugged construction and low-cost [1]. We have earlier reported the design of Nd:YAG/Cr ⁴⁺ :YAG passively Q-switched microchip lasers for efficient wavelength conversion from the second to the ninth harmonic [2]. These lasers are useful for spectroscopy, LIDAR, LIBS, materials micro-processing, etc.Here we report, for the first time, a novel method to end-pump a composite microchip laser with a slightly divergent free-space beam, obtained from a multi-single-emitter pump LD. Using this method, we can obtain a nearly circular TEM ₀₀ output beam, even though the pump beam is rectangular shaped. We get rid of the limitations of the fiber; the output beam is very stable and the laser size is reduced.