Frequency Characterization of an External-Cavity Quantum Cascade Laser at 4.5 μm using a Frequency Comb

Knabe, Kevin; Williams, Paul; Giorgetta, Fabrizio R.; Armacost, Chris M.; Radunsky, Michael B.; Newbury, Nathan R.

doi:10.1364/lacsea.2012.lt1b.4

Cited by 1 publication

(2 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The frequency variation of the central frequency is about 40 MHz peak-to-peak over 3 min. This value is very well comparable to the one measured in CW operation on a 4.5 µm EC-QCL, with a dedicated setup [15]. …”

Section: Resultssupporting

confidence: 85%

“…As was firstly suggested in [14], we propose here to retrieve the mid-infrared spectrum of an external-cavity QCL by upconversion in a nonlinear crystal, and analysis by a commercial near-infrared spectrometer. We have to note that, in a very recent paper [15], a similar method involving upconversion of frequency combs was used to analyze the frequency stability of EC-QCL. However, the bandwidth was limited to 50 MHz and did not allow following mode hops.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Time-resolved spectral characterization of a pulsed external-cavity quantum cascade laser

et al. 2012

View full text Add to dashboard Cite

Spectrally tunable narrow-linewidth mid-infrared sources are used in a variety of spectrometric optical systems for detection, identification, and/or quantification of chemical species. However, in the pulsed regime they often display a varying spectrum in time, either from shot-to-shot or during the pulse itself, with consequences on the measurement accuracy, resolution, and repeatability. This is, for instance, the case of pulsed quantum cascade lasers (QCL), mainly because of strong transient thermal effects in the optical waveguide. Unfortunately, little information has been published on this subject because mid-infrared time-resolved spectrometers are extremely scarce. In this paper, we explain how this can be circumvented by using time-gated frequency upconversion in a nonlinear crystal. We apply this principle to characterize a pulsed external cavity QCL (EC-QCL) at 7.8 µm, using AgGaS 2 as the nonlinear crystal and a Q-switched Nd:YAG laser as the pump source. The upconverted near infrared spectrum is conveniently analyzed with a high resolution lambdameter and an optical spectrum analyzer. We evidence frequency chirp at an average rate of -50 MHz/ns and mode hops spanning 15 GHz for the EC-QCL. These results are compared to published data.

show abstract

Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%