Gain squaring in a Cr:Nd:GSGG active-mirror amplifier using a cholesteric liquid crystal mirror

The small-signal gain of a Cr:Nd:GSGG active-mirror amplifier has been squared using a passive, 10- mu m-thick, cholesteric liquid-crystal selective reflection mirror. This double/double-pass configuration was easy to align and solved difficulties, such as polarization leakage and back-reflection coupling, which had plagued previous multipass schemes. The mechanism for this gain squaring is explained in terms of the optical properties of cholesteric liquid crystals.<
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