Demonstration of a 459-nm pulsed, optically pumped cesium vapor laser

We report on the demonstration of a pulsed cesium vapor laser operating in the blue via direct optical excitation of the 7P3/22 state. The cesium laser may be considered a three-level visible analog to the near infrared diode pumped alkali laser (DPAL). The 6S1/22–7P3/22 pump transition is collisionally broadened by helium. Population is rapidly transferred to the 7P1/22 state using ethane and lasing was observed on the 459.3 nm 7P1/22–6S1/22 transition. The best results were found with 550 Torr of helium and 100 Torr of ethane at cell temperatures from 90–110 °C. Using this setup, the maximum slope efficiency (0.45%) and lowest threshold pump energy (10μJ/pulse) were obtained. The maximum output energy was 3.3μJ/pulse, comparable to previous two-photon pumped blue laser demonstrations. Weak blue emission at 459 nm was also observed using 200–500 Torr of helium alone. A time-dependent rate equation model was developed to aid in the discussion of the intermultiplet mixing and strong infrared radiative transitions inherent in this system. A scalable alkali laser system operating in the blue near the Jerlov minimum has several possible communications, optical storage, color display and remote sensing applications.