Optically Pumped Atomic Rubidium Lasers: Two-Photon and Exciplex Excitation Mechanisms
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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The Doppler-broadened two-photon absorption TPA cross-section for the 52S12- 52D52 transition in Rb is measured using direct absorption methods. A detailed model of the intensity profile was developed to account for a focused Gaussian beam propagating through a two-photon absorption medium. A peak absorbance of 24 was observed for an intensity of 6.28 kWcm2 at the focus, a Rb density of 4.6 x 1015 cm-3 concentrations from 1.61-8.52 x 1015 cm-3 line. Extracting the hyperfine-broadened TPA cross-section from 87 test configurations, while varying the pump power, alkali concentration and focal length, yielded an error weighted average of 6.75x10-21 cm4W. This cross-section is sufficient for a pulsed dye laser to bleach the pump transition in the Two-Photon Pumped Alkali Laser TPAL that lases at 420 nm and 5.2 mum. Additionally, optically pumped atomic rubidium lasers pumped in the blue satellite of the D2 line from the ground Rb-Ar or Rb-Kr collision pair to the dissociative B2 sum 12 produce laser emission at 780.2 nm. Lasing is achieved for the Rb-Ar system and 757.1 - 760.4 nm for the Rb-Kr system. Slope efficiencies exceed 0.25 using a heat pipe configuration. The gain is very high with photon build-up times of 1-3.7 ns.
- Atomic and Molecular Physics and Spectroscopy