Wavelength and temporal requirements of tunable and single-frequency Ho lasers for LIDAR/DIAL applications

The authors have investigated the high-resolution spectral (wavelength) and temporal behavior of several different types of Ho lasers with an eye toward their use for atmospheric lidar and DIAL applications. These studies have indicated the importance in the precision characterization of the wavelength and temporal behaviour of the laser and how such performance can influence the measurements of an atmospheric lidar or DIAL system. The studies have included the study of (1) a high-power, pulsed (>300 mJ/pulse) Ho laser used for atmospheric lidar measurements, (2) a single-frequency CW microchip Ho laser to be used for injection seeding of a coherent Doppler lidar system, and (3) a tunable, CW single-frequency (traditional cavity) Ho laser to be used for atmospheric DIAL measurements of CO₂ and water vapor. The authors present an overview of their temporal and wavelength studies of Ho laser sources and the associated lidar/DIAL measurements that have been made. The studies of a high power Ho laser involved the development of a large, flashlamp pumped Cr,Tm,Ho:YAG laser that appeared to produce a 350 mJ Q-switched pulse