A new, miniature laser source developed by applied physicists in the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Technical University of Vienna (TU Wien) could soon pack the power of a laboratory-based spectrometer—an important workhorse tool for precision environmental gas analysis—onto a single microchip.

The device, a ring-shaped, “racetrack” quantum cascade laser, generates a specific type of light source, called a frequency comb, in the difficult-to-access mid-infrared region of the electromagnetic spectrum. It was developed in the lab of Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, in collaboration with co-senior author Benedikt Schwarz and colleagues at TU Wien.

The research was co-led by first author Ted Letsou, a postdoctoral researcher in the Capasso group, and Johannes Fuchsberger, a graduate student at TU Wien, and is published in Optica.