Measurements of cesium mixing and quenching cross sections in methane gas: understanding sources of heating in cesium vapor lasers.

Accurate modeling of the operation of diode-pumped alkali lasers is a critical step toward the design of high-powered devices. We present precision measurements for the Cs-CH 6P → 6P mixing cross section and the 6P → 6S quenching cross section, which are important parameters in understanding the operation and, in particular, the heat generated in a cesium vapor laser. Measurements are carried out using ultrafast laser pulse excitation and observation of fluorescence due to collisional excitation transfer in time is done using the technique of time-correlated single-photon counting.

Examination of potassium diode pumped alkali laser using He, Ar, CH and CH as buffer gas.

We examined the performance of a potassium diode pumped alkali laser (K DPAL) using He, Ar, CH, CH and a mixture of He and CH as a buffer gas to provide spin-orbit mixing of the 4P and 4P states of Potassium atoms. We found that pure helium cannot be used as an efficient buffer gas for continuous wave lasing without using a flowing system with a considerable flow speed of about 100 m/s. In contrast, using a small amount of methane (10-20 Torr) mixed with helium, continuous wave lasing can be achieved using very moderate flow speeds of about 1 m/s.

Modeling of pulsed K diode pumped alkali laser: Analysis of the experimental results.

A simple optical model of K DPAL, where Gaussian spatial shapes of the pump and laser intensities in any cross section of the beams are assumed, is reported. The model, applied to the recently reported highly efficient static, pulsed K DPAL [Zhdanov et al, Optics Express 22, 17266 (2014)], shows good agreement between the calculated and measured dependence of the laser power on the incident pump power. In particular, the model reproduces the observed threshold pump power, 22 W (corresponding to pump intensity of 4 kW/cm), which is much higher than that predicted by the standard semi-analytical models of the DPAL.

Efficient potassium diode pumped alkali laser operating in pulsed mode.

This paper presents the results of our experiments on the development of an efficient hydrocarbon free diode pumped alkali laser based on potassium vapor buffered by He gas at 600 Torr. A slope efficiency of more than 50% was demonstrated with a total optical conversion efficiency of 30%. This result was achieved by using a narrowband diode laser stack as the pump source.

Thermo-optical model of repetitively pumped solid-state lasers.

A thermo-optical model describing the cavity stability and TEM00-mode volume of a repetitively pumped solid-state laser is developed and verified experimentally. The model predicts a maximum theoretical TEM00 Gaussian-mode radius in the laser rod. This maximum mode radius is caused by a bifocusing of the cavity mode and is present even in gain-polarized materials that nominally suppress the effect of birefringence on beam polarization.

Raman and Rayleigh holographic lidar.

We have designed a novel rotational Raman and Rayleigh lidar system that incorporates a simple holographic optical element. The hologram simultaneously disperses and focuses the backscattered signal light so that narrow spectral features can be isolated and detected with high efficiency. By measuring the relative strength of several nitrogen rotational Raman lines, we can obtain an accurate temperature of the atmosphere at a given altitude without the need for external calibration.