High - Efficiency Laser Diode Arrays Pumped Nd: YAG Laser

Abstract

With the development of high-power LD arrays, there is a resurgence of interest in DPSSL. But a practical problem is that the output beams of LD have a large divergent angle, generally θ11 equal to 10° and θ⊥ equal to 40° or so. This caused a high loss of pumping power. Meanwhile one of the main obstruct in LD arrays end-pumped architecture is that the laser beams which emitted from unit bar can’t be focused as a single beam by imaging system, i.e. the light field distribution at the focal plane of the focusing system is inhomogeneous and the laser beam doesn’t match the cavity mode. This restricted the pumped efficiency and 1.06 μm laser beams quality. The coupling methods Currently adopted include: aspheric lens series[1], gradient refractive index lens[2], optical fiber[3] and “close” coupling[4]. But all kinds of these coupling systems have some defeats: low transfer efficiency; bad quality of laser beam and restraining the number of unit bars of LD arrays. Lens duct is a kind of good coupling system[5,6,7], we adopted it in our experiment to improve the total conversion translate efficiency and beam quality.