title: Room-temperature mid-infrared laser sensor for trace gas detection.
abstract: Design and operation of a compact, portable, room-temperature mid-infrared gas sensor is reported. The sensor is based on continuous-wave difference-frequency generation (DFG) in bulk periodically poled lithium niobate at 4.6 mum, pumped by a solitary GaAlAs diode laser at 865 nm and a diode-pumped monolithic ring Nd:YAG laser at 1064.5 nm. The instrument was used for detection of CO in air at atmospheric pressure with 1 ppb precision (parts in 10(9), by mole fraction) and 0.6% accuracy for a signal averaging time of 10 s. It employed a compact multipass absorption cell with a 18-m path length and a thermoelectrically cooled HgCdTe detector. Precision was limited by residual interference fringes arising from scattering in the multipass cell. This is the first demonstration of a portable high-precision gas sensor based on diode-pumped DFG at room temperature. The use of an external-cavity diode laser can provide a tuning range of 700 cm(-1) and allow the detection of several trace gases, including N(2) O, CO(2), SO(2), H(2) CO, and CH(4).
authors.forename: T
authors.initials: T
authors.lastname: Töpfer
authors.forename: K P
authors.initials: KP
authors.lastname: Petrov
authors.forename: Y
authors.initials: Y
authors.lastname: Mine
authors.forename: D
authors.initials: D
authors.lastname: Jundt
authors.forename: R F
authors.initials: RF
authors.lastname: Curl
authors.forename: F K
authors.initials: FK
authors.lastname: Tittel