Cascade and Two-Photon Lasing from Two-Photon Excitation of Cesium 6²D

Nathan D. Haluska

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Abstract

Cascade and two-photon lasing have been studied utilizing two-photon pumping of the Cs 6²D_3/2 and 6²D_5/2 states, with both pulsed and CW sources. This may enable a new generation of wavelength agile Diode Pumped Alkali Lasers (DPALs). Cascade lasing via Amplified Spontaneous Emission (ASE) is observed on over 17 transitions. Many lines have 100 to 229 µJ of energy, slope efficiencies of 4 to 7%, and low thresholds favorable for diode pumping. Potential applications include IR counter measures, target illuminators, beacon lasers, underwater communication, and other tactical applications. We also observed two nonlinear, wavelength tunable, two-photon lines. The first occurs near 1380 nm on the 7²S_1/2 → 6²S_1/2 transition. The second occurs near 3120 nm on the 5²D_3/2 → 6²S_1/2 transition. A CW 3 µm laser is generated by two-photon pumping with a 1 W pump. We observed a corrected power of 750 µW, absorption corrected efficiency of 0.7%, and lasing thresholds /cm². Our results demonstrate that a two-photon DPAL is feasible.