A pulsed, optically pumped rubidium laser operating in analogy to the diode pumped alkali laser (DPAL) system at pump intensities as high as 750 kW/cm2 has been demonstrated with output energies of up to 13 μJ/pulse. Output energy is dramatically limited by spin‐orbit relaxation rates under these high intensity pump conditions. More than 250 photons are available for every rubidium atom in the pumped volume, requiring a high number of cycles per atom during the 2–8 ns duration of the pump pulse. At 550 Torr of ethane, the spin‐orbit relaxation rate is too slow to effectively utilize all the incident pump photons. Indeed, a linear dependence of output energy on pump pulse duration for fixed pump energy is demonstrated.A pulsed, optically pumped rubidium laser operating in analogy to the diode pumped alkali laser (DPAL) system at pump intensities as high as 750 kW/cm2 has been demonstrated with output energies of up to 13 μJ/pulse. Output energy is dramatically limited by spin‐orbit relaxation rates under these high intensity pump conditions. More than 250 photons are available for every rubidium atom in the pumped volume, requiring a high number of cycles per atom during the 2–8 ns duration of the pump pulse. At 550 Torr of ethane, the spin‐orbit relaxation rate is too slow to effectively utilize all the incident pump photons. Indeed, a linear dependence of output energy on pump pulse duration for fixed pump energy is demonstrated.

AIP conference proceedingsJan 1, 20100 citations

Production of highly spin-polarized atomic hydrogen and deuterium by spin-exchange optical pumping

S. G. Redsun, R. J. Knize, G. D. Cates +1 more

We have produced highly spin-polarized atomic hydrogen by spin-exchange optical pumping. A tunable ring dye laser is used to polarize rubidium atoms by optical pumping. The cell containing the rubidium vapor is coated with paraffin in order to reduce spin relaxation due to wall collisions. Hydrogen gas is dissociated in an inductive discharge and flows continuously through the cell, in which the hydrogen atoms are polarized by spin-exchange collisions with the polarized rubidium atoms. Atomic-hydrogen polarization as high as 2〈 ${\mathit{J}}_{\mathit{z}}$ ${\mathrm{〉}}_{\mathrm{H}}$ =0.72(6) has been observed, which is the highest polarization yet produced by this method. However, the rubidium polarization may be limited to this value due to radiation trapping at higher rubidium densities. The spin-relaxation rate of atomic hydrogen on a paraffin-coated cell is also measured and corresponds to about 7600 wall bounces between wall relaxation.We have produced highly spin-polarized atomic hydrogen by spin-exchange optical pumping. A tunable ring dye laser is used to polarize rubidium atoms by optical pumping. The cell containing the rubidium vapor is coated with paraffin in order to reduce spin relaxation due to wall collisions. Hydrogen gas is dissociated in an inductive discharge and flows continuously through the cell, in which the hydrogen atoms are polarized by spin-exchange collisions with the polarized rubidium atoms. Atomic-hydrogen polarization as high as 2〈${\mathit{J}}_{\mathit{z}}$${\mathrm{〉}}_{\mathrm{H}}$=0.72(6) has been observed, which is the highest polarization yet produced by this method. However, the rubidium polarization may be limited to this value due to radiation trapping at higher rubidium densities. The spin-relaxation rate of atomic hydrogen on a paraffin-coated cell is also measured and corresponds to about 7600 wall bounces between wall relaxation.

Physical Review AAug 1, 199035 citations

Influence of Broadband Excitation on the Performance of Diode Pumped Alkali Lasers

Paul Nathaniel Jones, Gordon D. Hager, Glen P. Perram

A three level model for optically pumped alkali metal vapor lasers is developed by considering the steady state rate equations for the longitudinally averaged number densities of the ground 2 S1/2 and first excited 2 P3/2, and 2 P1/2 states. For efficient operation, the collisional relaxation between the two upper levels should be fast relative to stimulated emission. By assuming a statistical distribution between the upper two levels, the limiting analytic solution for the quasi-two level system is achieved. A second limiting solution is identified for strongly bleached conditions where the atom recycle rate, limited by spin-orbit relaxation, fully specifies the output power. Performance in the intermediate regime depends significantly on pump laser bandwidth and requires numerical simulation. The ratio of populations for the two excited, 2 P3/2,1/2 states completes an analytic solution and depends primarily on pump laser bandwidth, threshold and alkali concentration.A three level model for optically pumped alkali metal vapor lasers is developed by considering the steady state rate equations for the longitudinally averaged number densities of the ground 2 S1/2 and first excited 2 P3/2, and 2 P1/2 states. For efficient operation, the collisional relaxation between the two upper levels should be fast relative to stimulated emission. By assuming a statistical distribution between the upper two levels, the limiting analytic solution for the quasi-two level system is achieved. A second limiting solution is identified for strongly bleached conditions where the atom recycle rate, limited by spin-orbit relaxation, fully specifies the output power. Performance in the intermediate regime depends significantly on pump laser bandwidth and requires numerical simulation. The ratio of populations for the two excited, 2 P3/2,1/2 states completes an analytic solution and depends primarily on pump laser bandwidth, threshold and alkali concentration.

AIAA Plasmadynamics and Lasers ConferenceJun 1, 20113 citations

{\mathit{J}}_{\mathit{z}}

{\mathrm{〉}}_{\mathrm{H}}

=0.72(6) has been observed, which is the highest polarization yet produced by this method. However, the rubidium polarization may be limited to this value due to radiation trapping at higher rubidium densities. The spin-relaxation rate of atomic hydrogen on a paraffin-coated cell is also measured and corresponds to about 7600 wall bounces between wall relaxation.