Optical Pumping and Related Topics

J. Brossel

L. A. Lugiato, Lorenzo M. Narducci

Jun Xiong Gao, Pengfei Sun, Xinbing Wang +1 more

Abstract Optically pumped metastable argon laser is an attractive research topic of innovative gas lasers, but the slow collisional relaxation rates of 1 s 4 –1 s 5 (in Paschen notation) may form a bottleneck on the cycling of active atoms and decrease the laser output at room temperature. Here, by employing a method of a dual-wavelength pump, we demonstrate the removal of accumulation on the 1 s 4 level and the improvement of output power in the simulation. The simulated results show that a large increase in laser output is possible with a relatively weak assistant pump intensity. This method offers a feasible way to scale the laser to higher gain.

Robert A. Bernheim, Ernst K. Franke

P. R. Berman

In 1950, Professor Alfred Kastler described the way in which optical fields could be used to redistribute population among the Zeeman sublevels of a given atomic state. The « optical pumping » process discovered by Kastler continues to be a research topic of current interest. With developments in laser spectroscopy, it has become important to understand the interplay of optical pumping, transit-time and collisional effects to properly interpret experimental line shapes. A brief review of the current status of the theory is given, with special emphasis on what, as yet, appear to be unresolved problems. Velocity selective optical pumping and collision-induced resonances are discussed.

John P. Revelle, Ankit Kumar, Alexander F. Kemper

Time-resolved optical conductivity is an often used tool to interrogate quantum materials driven out of equilibrium. Theoretically calculating this observable is a complex topic with several approaches discussed in the literature. Using a nonequilibrium Keldysh formalism and a functional derivative approach to the conductivity, we present a comparison of two particular approaches to the calculation of the optical conductivity and their distinguishing features, as applied to a pumped superconductor. The two methods are distinguished by the relative motion of the probe and gate times; either the probe or gate time is kept fixed while the other is swept. We find that both the methods result in same qualitative features of the time-resolved conductivity after pump is over. However, calculating the conductivity by keeping the gate fixed removes artifacts inherent to the other method. We provide software that, based on data for the first method, is able to construct the second approach.