Theoretical studies of fundamental processes relevant to diode pumped alkali lasers
Abstract
A research aimed on studying fundamental processes relevant to cesium and potassium DiodePumped Alkali Lasers (DPALs) is proposed. The research is motivated by recent experimentsaimed at increasing DPALs output power, which have revealed some limiting effects such asoutput power degradation in time, decrease in laser efficiency and termination of lasing. Also,catastrophic damage of the alkali vapor cell and gain medium contamination has been observed.Several fundamental physical processes can be responsible for these limiting effects and stronglylimiting the output power of DPALs. These processes include finite relaxation rate between thefine-structure levels n2P3/2 and n2P1/2 of the alkali atoms, photoexcitation and ionization of theatoms, quenching of the high electronic levels of these atoms, chemical reaction between thehighly excited atoms and hydrocarbons (methane or ethane), usually present in the laser mediumof the DPALs, heating of the gain medium, and thermal breakdown of the hydrocarbons. At highpumping power (> 100 W) the finite relaxation rate may cause saturation of the pump D2 transitionresulting in pump bleaching and strong decrease of the pump absorption. The heat release due torelaxation between the fine-structure levels of alkali atoms and quenching of these levels resultsin considerable increase of the temperature in the lasing medium, which can achieve severalhundred K. The temperature increase causes increase of the thermal population of the n2P3/2 leveland hence decrease of the pump absorption on the D2 transition. In addition, non-uniformtemperature distribution can result in thermal lensing effects. The proposed basic research istargeted at studying these and other possible fundamental processes affecting operation of DPALs,especially at high power levels, and research possible ways to mitigate these parasitic processes.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 11, 2018
- Source ID
- FA95501810204
Entities
People
- Salman Rosenwaks
Organizations
- Air Force Office of Scientific Research
- Ben-Gurion University of the Negev
- United States Air Force