We examined the performance of potassium diode pumped alkali laser (K DPAL) using He, Ar, Methane (CH4), Ethane (C2H6) and a mixture of He and CH4 as a buffer gas to provide spin-orbit mixing of the 4P3/2 and 4P1/2 states of Potassium atoms. We found that pure helium as an efficient buffer gas for K DPAL with a static gain medium can be used only for pulsed operation with up to 50 µs pulse durations. The performance degradation of K DPAL with pure helium for longer pulses can be explained by ionization, which causes an effective reduction in neutral alkali atoms number density. Using a flowing system for the K DPAL allows improving its operation in continuous wave (CW) mode, but for efficient lasing with pure He buffer gas, a considerable flow speed of about 100 m/s is required. In contrast, using a small amount of methane or ethane (10-20 Torr) mixed with helium at total pressure of about 1 atm, an efficient continuous wave lasing can be achieved with very moderate flow speeds of about 1 m/s. Argon buffer gas was also tested in this experiments, but it did not support lasing neither in pulsed nor in CW mode of K DPAL operation.
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