Detection of trace gas contaminants using diode laser based methods

In recent years, tunable diode laser based sensors have found widespread applications to the sensitive and selective detection of environmentally important atmospheric trace gases in real time. Numerous analytical tools based on different optical and non-optical techniques have been developed in the past. However, an ideal gas sensor technology that meets such diverse requirements as high sensitivity and selectivity, wavelength tunability of multi-component detection, fully computerized, room temperature operation (i.e. no liquid nitrogen cooling), large dynamic range, compactness, high reliability (insensitive to vibrations and large variations in ambient temperature), relative ease of use and cost-effectiveness in terms of initial and maintenance costs, is a challenging research and development task. Recent significant technological advances of semiconductor diode lasers and tunable all solid state lasers, novel bulk and waveguide infrared nonlinear materials for parametric optical frequency conversion, optical fiber amplifiers and couplers, thermoelectric coded low noise infrared detectors, and advanced data acquisition and signal processing techniques have had a considerable impact on development of state of the art of diode laser based trace gas sensors.