Optical re-injection in cavity-enhanced absorption spectroscopy

Cavity-enhanced absorption spectroscopy of molecular oxygen

A high-finesse optical cavity was employed to perform highly sensitive spectroscopy of molecular oxygen at wavelengths near 763 nm. An equivalent absorption length of ;1 km was obtained by a 26-cm-long optical cavity with a finesse of 6000. An extended cavity diode laser was frequency locked to the cavity, and pure absorption profiles were recovered by monitoring of the cavity transmission duri...

Optical injection unlocking for cavity ringdown spectroscopy.

Continuous wave cavity ringdown spectroscopy requires a rapid termination of the injection of light into the cavity to initiate the decay (i.e., ringdown) event. We demonstrate a technique that accomplishes this through pulsed optical injection of a second laser into the main laser, resulting in 20-100 MHz frequency shifts in the otherwise cavity-locked main laser sufficient to create ringdown ...

Cavity-enhanced spectroscopy in optical fibers.

Cavity-enhanced methods have been extended to fiber optics by use of fiber Bragg gratings (FBGs) as reflectors. High-finesse fiber cavities were fabricated from FBGs made in both germanium/boron-co-doped photosensitive fiber and hydrogen-loaded Corning SMF-28 fiber. Optical losses in these cavities were determined from the measured Fabry-Perot transmission spectra and cavity ring-down spectrosc...

Detection of Optical Radiation in NOx Optoelectronic Sensors Employing Cavity Enhanced Absorption Spectroscopy

Optical cavity enhanced real-time absorption spectroscopy of CO2 using laser amplitude modulation