Study on high power green lasers with unstable resonators
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Graphical Abstract
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Abstract
In order to improve its laser beam quality,obtain collimated laser beam and provide an excellent high-power green laser source to pump Ti:sapphire,a diode-side-pumped acoustic-optic Q-switched intra-cavity frequency doubling Nd:YAG laser was studied.In the experiment,a convex-plane unstable resonator was adopted assuming the convex mirrors and gain medium thermal lens as a telescope system.Experimental results show that a convex-plane unstable resonator has lager mode volume and better stability.Using a second type phase-matched KTP(KTiOPO4) for intra-cavity frequency doubling,with 200W pump power,42W green laser was output with 109ns pulse width,9.3kHz pulse repetition frequency,less than 2mrad divergent angle,21% optical-optical conversion efficiency and instability less than 2% during 24h work.It is proven that an effective output of green laser can be achieved with an unstable resonator and side pump module.
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