Gerard Wysocki, PhD

Faculty Fellow
Department of Electrical and Computer Engineering
Rice University

Development of Tunable Infrared Quantum Cascade Laser Sources

Laser based trace gas sensors and their application to environmental monitoring, industrial process control, and medical diagnostics requires the availability of single frequency and tunable laser sources. In the mid-infrared molecular fingerprint region quantum cascade lasers (QCLs) have proved to be convenient light sources for the spectroscopic detection of trace gases1. Single frequency operation is usually achieved by introducing a distributed feedback (DFB) structure into the QCL active region. Therfore the total range of wavelength tuning of the emitted laser radiation is limited to ~10 cm-1 by the thermal wavelength tuning range of the DFB structures. This presentation describes recent progress in the development of widely tunable QCL technology for sensitive, selective single and multi species trace-gas detection in the mid-infrared. The implementation of this technology is based on a novel grating controlled external cavity (EC) QCL architecture which employs a piezo-activated mode tracking system for precise wavelength tuning and frequency control. The mode-tracking system provides independent control of the EC length, diffraction grating angle and laser current. The system performance and spectroscopic application capability was demonstrated with a QCL gain medium operating at ~ 5.2 µm. The flexibility of this arrangement makes it possible to use it with other QCLs in different infrared spectral regions without changing the basic sensor configuration.

Reference:

  1. G. Wysocki, R.F. Curl, F.K. Tittel, R. Maulini, J.M. Bulliard, J. Faist, "Widely Tunable Mode-hop Free External Cavity Quantum Cascade Laser for High Resolution Spectroscopic Applications," Applied Physics B, 81, 769-777 (2005)
Thursday, September 7, 2006
3:00 p.m. - Duncan Hall 1049
Rice University

ECE Affiliates Meeting



Last modified: August 10, 2006