Time Resolved Characterization of Fabry-Perot Quantum Cascade Lasers for Use in a Broadband "White Light" Source
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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We report the time resolved characterization of Fabry-Perot quantum cascade lasers FP-QCLs. We are developing a custom-built broadband laser source in the Mid-LWIR range by combining several high power FP-QCLs for a single snap shot application. This white light source would enable not only stand-off detection applications in a single snapshot but also new data collection modalities such as live, real-time chemical imaging, requiring extremely rapid measurements. In this study, the two FP-QCLs were operated in CW and pulsed modes with varying applied currents and diode temperatures to optimize the best laser operation condition to cover a broad spectral range including spectral features for the analytes of interest. To understand mode behavior of the FP-QCLs in a short period of time, the spectral output for each test condition was temporally resolved. Under most of the conditions, FP mode hopping was observed during the time evolution through the pulse length 30X ns. Based on the time-resolved spectra, the ideal spectral characteristics for a single snap shot application are discussed, with respect to a broad spectral bandwidth, a flat-top power profile, and high spectral power density.
- Lasers and Masers