Scaling of an Optically Pumped Mid-Infrared Rubidium Laser.

摘要

An optically pumped mid-infrared rubidium (Rb) pulsed laser has been demonstrated in a heat pipe along the 62P3/2 - 62S1/2 transition at 2.730 micrometer and the 62P1/2 - 62S1/2 transition at 2.790 micrometer. The bleached limit, slope efficiency, and maximum laser output energy of the mid-IR Rb laser have been shown to scale linearly with increasing Rb density, contrary to prior laser demonstrations. A maximum output energy of ~5 nJ per pulse had previously been observed before a rollover occurred in the scaling of output energy with Rb concentration. In this experiment, the maximum laser output energy observed was ~100 nJ, with linear scaling to a Rb concentration of 7 x 10 to the 15th power cm-3. A maximum slope efficiency of 1.7 x 0.0001 was observed. Evidence that only a small percentage (<2%) of the available pump photons were absorbed at a concentration of 2 x 10 to the 15th power cm-3 and a pump energy of 10 (mu)J. This indicated that there were 20,000 pump photons per Rb atom at a pump energy of 10 mJ, and that the effective laser efficiency was 0.65 percent or higher. The hyperfine structure and absorption spectral profile of the 52S1/2 - 62P1/2 and 52S1/2 - 62P3/2 (blue) pump transitions were studied using a continuous wave (cw) pump source.