A.K.Y. Ngai

Selective trace gas detection of complex molecules with a continuous wave optical parametric oscillator using a planar jet expansion

The authors present a trace gas detection method for complex molecules using continuous cavity ring-down spectroscopy in combination with a continuous wave optical parametric oscillator (tunability wavelength: 2.8–4.8μm; power: 1W) sampling a supersonic planar jet expansion (nozzle dimension: 3cm×80μm). The improved molecular selectivity allows simultaneous detection of larger numbers of complex molecules. With a total optical path length of 180m in the planar jet, a detection limit for methanol in an air expansion was determined at 70ppbv, corresponding to a minimal detectable absorption of 2.2×10−8cm−1 (over 90s).

Broadly tunable, continuous-wave OPO for high resolution spectroscopy

We present a high power, broadly tunable (2.75-3.83 mum) cw OPO based on PP-MgO-LN. Using a combination of tuning techniques, molecular absorption spectra can be continuously recorded over 450 cm-1 at Lt0.001 cm-1 resolution.

Fast-Scanning Fibre-Amplified Diode Laser Pumped cw OPO for Sensitive, Multi-Component Trace Gas Detection

An 800 mW, fast scanning (100 THz/s), continuous wave optical parametric oscillator (3-4 mum) pumped by a fibre-amplified diode laser is used for sensitive (1.5 times 10^-8 cm^-1 Hz^-1/2), multi-component trace gas detection.

Sensitive Trace Gas Detection in a Jet Expansion Using cw OPO-based Cavity Ringdown Spectroscopy

We present a novel approach to trace gas detection of more complex molecules, based upon a combination of continuous cavity ringdown spectroscopy using a cw infrared OPO system and supersonic planar jet.

Sensitive and fast trace gas detection by means of OPO-based cw cavity ring down spectroscopy

A 2 W, continuous-wave, widely and continuous tunable, singly frequency, mid-infrared optical parametric oscillator is used in combination with cavity ring down spectroscopy for the fast and sensitive detection of trace gases.