Highly efficient emerald laser

The laser-relevant spectroscopic parameters in emerald are characterized. Polarized spectra of the absorption cross sections and excitation and emission cross sections were measured. Highly efficient laser operation has been achieved. In a quasi-cw laser-pumped emerald laser, a 64% output-slope efficiency was measured at 768 nm, corresponding to a laser quantum yield of 76%. The maximum output power reached 1.6 W, at 3.6 W of pump power at 647.1 nm, and was pump-power limited. The emerald laser was tuned from 720 to 842 nm. Emerald has good pump and fluorescence efficiencies. The round-trip laser loss, excluding the excited-state absorption (ESA), is 0.4%/cm. In high-optical-quality emeralds, the ESA loss becomes the main factor that limits laser efficiency.