DPAL: A new class of lasers for cw power beaming at ideal photovoltaic cell wavelengths

The new class of diode pumped alkali vapor lasers (DPALs) offers high efficiency cw laser beams at wavelengths which efficiently couple to photovoltaic (PV) cells: silicon cells at 895 nm (cesium), and GaAs cells at 795 nm (rubidium) and at 770 nm (potassium). DPAL electrical efficiencies of 25–30% are projected, enabling PV cell efficiencies ∼40% (Si) and ∼60% (GaAs). Near‐diffraction‐limited DPAL device power scaling into the multi‐kilowatt regime from a single aperture is projected. The potential application to power beaming propulsion to raise satellites from LEO to Geo is discussed.