Tunable laser spectroscopy system with gas line resolution

Abstract

A spectroscopy system and method enhance the resolution of narrow spectral features by modulating the injection current of a gain chip in a tunable laser. The system includes a tunable laser with an external cavity formed between the gain chip and an external reflector, containing a wavelength-selective element like a tilt-tuned interference filter. An oscillator drive signal modulates the injection current at high frequency and amplitude, altering the effective optical length of the external cavity and shifting the cavity modes over a range sufficient to resolve narrow spectral lines. This modulation ensures effective interaction with narrow absorption features in the sample. Operating at frequencies above the detector's bandwidth allows averaging over the modulation, reducing noise and improving signal quality. This technique is particularly beneficial for low-pressure gas spectroscopy, enabling precise detection and analysis of specific species within a sample.

Dependencies are inferred from the claim text.