Dr. Christopher R. Webster (PI) and Gregory J. Flesch (Co-I)

Collaborators: Dr. Claire Gmachl and Dr. Federico Capasso (Bell Laboratories), Dr. Tobias Owen (University of Hawaii), Professor Yuk L. Yung (Caltech)

We are currently prototyping the first of a new generation of miniature tunable laser mid-IR spectrometers operating at room temperature for in situ measurement of atmospheric and evolved planetary gases. The all-solid-state spectrometer will be based on newly-available room-temperature quantum-cascade (QC) laser sources in the 3-12 m m wavelength region. The QC laser spectrometer would have immediate applications to Mars, Titan, Venus and Europa missions, could be operated on a descending or penetrating probe, lander, rover, or aerobot, would consume only a few watts of power, and weigh less than one kilogram. Because it directly accesses the wavelength region of strong vibration-rotation spectral lines, the QC laser spectrometer has wide-ranging and immediate application to measuring concentrations of several planetary gases such as H₂O, CH₄, CO, CO₂ , C₂H₂, HCN, C₂H₆, C₂N₂, HC₃N, O₃, OCS, H₂S, and SO₂, and numerous stable isotopes. Such measurements could be made to study atmospheric photochemistry and transport, mineralogical and biological experiments (e.g. quantification of evolved gases and their isotopic fractionation from thermal decomposition of minerals or ice), and respiratory or hazardous gas monitoring for human exploration of the solar system.

A huge leap in laser technology has been made in the last year or so that has produced room-temperature tunable laser sources in the mid-IR from a revolutionary new approach to laser fabrication, that of quantum engineering of electronic energy levels to produce quantum-cascade (QC) lasers (3-12 m m). These lasers are fundamentally different from diode lasers in that the wavelength is essentially determined by quantum confinement, i.e. by the thickness of active layers rather than the energy bandgap of the material. These new devices produce single-mode laser light tunable over 10-20 cm^-1, of output power of fractions of a watt. The technological breakthrough provided by the invention of the QC laser offers a ten-fold increase in our current ability to address science objectives for planetary missions.