1 Department of Photonics Engineering, Technical University of Denmark2 Optical Sensor Technology, Department of Photonics Engineering, Technical University of Denmark3 Risø National Laboratory for Sustainable Energy, Technical University of Denmark4 Lund University5 Lund University
We compare a nonlinear upconversion detector with a conventional cryogenic InSb detector for the detection of coherent infrared light showing near-shot-noise-limited performance in the upconversion system. The InSb detector is limited by dark noise, which results in a 500 times lower signal-to-noise ratio. The two detectors are compared for the detection of a coherent degenerate four-wave mixing (DFWM) signal in the mid-infrared, and applied to measure trace-level acetylene in a gas flow at atmospheric pressure, probing its fundamental rovibrational transitions. In addition to lower noise, the upconversion system provides image information of the signal, thus adding new func- tionality compared to standard point detectionmethods.We further show that the upconversion detectorsystem can be implemented as a simple replacement of the cryogenic detector.
Optics Letters, 2014, Vol 39, Issue 18, p. 5321-5324