New quantum racetrack laser design could shrink lab spectrometers onto microchips

Researchers at Harvard and TU Vienna built a compact racetrack quantum cascade laser that produces a stable mid-infrared frequency comb.

The closed-loop racetrack design forces unidirectional light travel and reduces disruption from optical feedback.

Metallic probes deliver a radio-frequency drive matched to the light round-trip, removing external stabilizers.

The chip-scale lasers maintained stability under direct feedback and could enable compact dual-comb spectrometers for gas sensing.

The study is published in the journal Optica.