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In this paper, we discuss the characterization of several quantum cascade lasers (QCL) as candidates for a broadband infrared illumination source for use in single “snapshot” detection of hazardous materials. Each of the lasers discussed is a Fabry-Perot quantum cascade laser (FP-QCL) chosen for its peak emission within the mid- to long-wave infrared region of 7 µm to 12 µm. These lasers are commercially available from several vendors. The output of each laser was characterized using a high resolution FTIR spectrometer to record each laser’s emission spectrum under varying operating conditions such as driving current, QCL temperature, and operating modes (continuous wave or pulsed). Time-Resolved Spectroscopy (TRS) was performed on each laser’s pulsed driven output to provide further details on how the emission of each laser evolves on the nanosecond time scale. We specifically investigate and present spectra of FP-QCL packaged in sealed OEM configurations. These devices offer center wavelengths ranging from 8.9 µm to 10.5 µm. We present the results of changing operating conditions to optimize the QCL emission to provide high-power and broad spectral coverage. By combining two or more FP-QCL, we obtain spectral coverage of approximately 3 µm. The purpose of this study is to develop a high-power, broadband, “white light” illumination source to provide wide spectral coverage over the region of interest for standoff detection and analysis of potentially hazardous materials.
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