Diode Laser Injection Seeded, Raman Shifted Alexandrite Laser Tunable Narrowband Lidar Source

The immediate purpose of this work is to develop robust, reliable, spectrally narrow light sources for optical remote sensing and specifically for certain atmospheric Lidar studies. One application is the study of the mesospheric sodium layer (80-100 km altitude) to determine altitude profiles of atomic density and temperature. For this purpose we have undertaken comparison of the Na (D2) radiation at 589.159 nm produced by either anti-Stokes or frequency doubled first Stokes conversion of alexandrite laser wavelengths. A second application is the profiling of atmospheric water vapor by means of differential absorption Lidar (DIAL) utilizing alexandrite fundamental and Stokes shifted outputs in the 730 nm, 940 nm and 1140 nm bands of water vapor. The 1.4 μm water vapor band also is accessible using output from the Second Stokes shift of alexandrite (at 760 nm) radiation in D2 gas.