The Diode Pumped Alkali Laser (DPAL) system originally proposed and demonstrated by Krupke is a three level laser pumped by diode bars on the D2 transition, exciting the first 2P3/2 state of the alkali atom. Collisional relaxation to the 2P1/2 state is accomplished with a spin orbit relaxing gas such as ethane or methane, while pressure broadening of the absorption line has routinely been accomplished with He. The excited alkali atom then lases on the D1 line back to the ground state. Terminating the laser level at the ground state requires the gain volume to be fully bleached before achieving an inversion between the 2P1/2 and 2S1/2 states, resulting in pump threshold values of ~1 kW/cm2. Early laser demonstrations achieved laser output powers of 1-3 W in both rubidium and cesium with slope efficiencies as high as 82%. More recently, cw output powers as high as 145 W with in-band slope efficiencies of 28% have been reported.
This course will develop the background spectroscopy and kinetics of the DPAL system, summarize recent laser demonstrations, discuss narrow banding of diode pump sources, develop the key performance and scaling equations, and outline several issues in the development of these devices for tactical weapons applications.
The course outline is as follows:
The course is intended for scientists and engineers with a basic understanding of laser engineering.Instructor Biographies
Glen Perram, Professor of Physics, AFIT. B.S. Cornell University 1980, M.S. AFIT 1981, Ph.D. AFIT 1986. Professor Perram's research experience includes chemical lasers, laser weapon modeling and simulation, remote sensing, and chemical physics. He has served on the AFIT faculty since 1989 and is the author of over 30 archival publications and 80 pres-entations. He is a Fellow of the Directed Energy Professional Society.