Photoacoustic trace gas detection of ethane using a continuously tunable, continuous-wave optical parametric oscillator based on periodically poled lithium niobate

Abstract

A 1.2 W, continuous-wave, continuously-tunable, singly-resonant optical parametric oscillator ͑OPO͒ ͑idler tuning range 3.0-3.8 m͒, pumped by a 10 W continuous-wave Nd:YAG laser, is used in combination with a photoacoustic cell for the detection of ethane. An intracavity solid-state etalon ͑thickness 400 m͒ was used to stabilize the OPO cavity and could be used to mode-hop tune the idler wavelength over 10 cm Ϫ1. The usefulness of the system was demonstrated by determining a detection limit for ethane down to 10 parts per trillion. The selectivity was achieved by making a 24 GHz wide pump laser scan over the ethane absorption line at 2996.9 cm Ϫ1 , after which a Lorentzian fit determined the total area of the absorption signal. Both area value and peak value proved to be linearly depending on the ethane concentration.

Mid-infrared detection of trace biogenic species using compact QCL based integrated cavity output spectroscopy (ICOS)

“…Using a multi-watt OPO at 3 microns, and photoacoustic spectroscopy, Van Herpen and co-workers demonstrated a 10 ppt detection with a 40s integration time. 12 Von Basum and coworkers have demonstrated a detection limit 0.5 ppt in a 3 minute integration time using cavity leak out spectroscopy and a cw OPO for ethane in air and breath. 13 Requirements for the analysis of carbon monoxide in breath are much less demanding since the concentration of carbon monoxide is much higher than ethane (1ppm vs 1 ppb).…”

Online, real-time detection of volatile emissions from plant tissue

“…As an example, the linear response of the photoacoustic sensor for low detection limits of ethane is presented in Fig. 2 (van Herpen et al . 2002).…”

Continuous‐wave optical parametric oscillator based infrared spectroscopy for sensitive molecular gas sensing

“…OPO‐based gas spectroscopy relies on the use of cw and pulsed OPOs. OPOs have proven to be excellent sources for spectroscopy within Doppler‐free spectroscopy that relies on the reliable tuning characteristics and narrow linewidth of OPOs , ; Photoacoustic spectroscopy that utilizes the power of OPOs in the infrared , ; Cavity ring‐down spectroscopy that benefits from the narrow linewidth attainable by cw OPOs , and frequency/wavelength modulation spectroscopy that profits from the ease of modulation for certain types of OPOs . In this work, a number of these schemes are demonstrated and evaluated, and applications in atmospheric, medical and life sciences are presented.…”