Abstract

Development of high energy class lasers has attracted the scientific community in recent years because of their vast scientific and technological applications such as laser-driven inertial fusion energy, laser shock peening for hardening of metals and for laser induced damage threshold measurements. To develop systems of this kind Yb:YAG was used as the active material and cooled to cryogenic temperatures due to the fact that spectroscopic and thermo-optical properties enhance. Many works on cryogenic Yb:YAG lasers are based on 940 nm pumping because of the good match of the pump and absorption bands. Other possibilities to develop such systems are to use zero phonon line pumping (ZPL) at 969 nm. The advantage of ZPL pumping is that the quantum defect is reduced by 3% which significantly reduces the diffraction losses caused by thermally induced phase distortions, as reported [1] which has direct implications of increasing slope efficiency. However, at cryogenic temperature the absorption band-width of Yb:YAG at ZPL narrow down tremendously [2] and one has to keep in mind the band-width of the pump source. Nowadays, volume Bragg grating (VBG) stabilized narrow band-width pump sources are available in the market of our choice it is possible to use these as pump sources. We present here highly efficient continuous-wave laser performance of Yb:YAG laser pumped by VBG stabilized narrow band fiber coupled diode at 969nm.

© 2015 IEEE