Concepts for scalable CDMA-networked M/LWIR semiconductor laser standoff chemical detection system

Mid-wave/Long-wave IR (3-14 um) semiconductor lasers such as QC and Sb can be used for standoff chemical agent sensing in a network architecture that is different from conventional absorption lidars. Compact, potentially inexpensive semiconductor lasers may allow using them in a large number that form a cooperative network in which, the integrated sensing information is much more than the sum of Its parts. This paper presents a study of system architecture based on CDMA, similarly to a CDMA optical wireless network, which allows a system of many distributed units to plug-and-play, and cooperate with each other for N-2 information scaling, rather than interfering with each other in non-networked architecture. This paper describes experimental studies with this system architecture, conducted with M/LWIR lasers, near-IR lasers, using wavelength-division-multiplexing (WDM) technique for high spectral fidelity, optical scanner for multi-spectral imaging, and simulated spatially distributed transmitters and receivers for sensor network. Specifically, the use of advanced lasers capable of broad and continuous wavelength timing and modulation for WMS imaging is described. The experimental results suggest that M/LWIR spectral imaging with WDM multi-spectral transmitters is highly promising for chemical agent detection and visualization.