Tunable infrared laser sources for DIAL

Broadly tunable infrared laser sources are of interest for a variety of applications including differential absorption lidar, differential scattering lidar, multi-spectral detection and imaging, hard target identification and discrimination, optical communications in poor visibility conditions, and spectroscopy. For chemical sensing applications, sources are particularly sought in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) spectral regions. A variety of laser and nonlinear optical devices have been demonstrated that access these wavelengths. In particular, CTI is developing novel, tunable, narrow linewidth transmitters for coherent and direct detection lidar measurement applications. An example is a multi-watt Cr:ZnSe laser that is tunable over the 2.1 to 2.8 micrometers wavelength region. This laser has been used to pump-tune optical parametric oscillators (OPOs) that are broadly tunable across the MWIR and LWIR. We are also developing tunable Yb lasers that can be used to pump OPOs that emit signal beams in the eyesafe 1.55 micrometers region while generating idler beams that access the 3 to 4 micrometers MWIR band. This paper describes these sources.