Abstract

There is an increasing demand of laser sources in the 7–9 µm wavelength range for stand-off detection of chemical traces. One key requirement for those kinds of applications is a fast and large spectral tunability with a narrow linewidth. On one hand, narrow-linewidth pulsed optical parametric oscillators (OPO) solutions usually lead to complex systems with slow tuning means. On the other hand, external-cavity quantum cascade lasers (EC-QCL) have demonstrated a very broad tunability (~300 cm⁻¹) [1] with narrow linewidths and excellent beam quality. However, their relatively low peak power limits the stand-off detection range to a few meters. We present here a tunable laser system in the long-wave infrared using an EC-QCL, optical parametric amplification (OPA) to amplify the QCL emission with high gain while preserving its spectral and spatial properties [2] and a thulium-doped fiber pump system with fast tunability.

© 2015 IEEE