title: Compact CH4 sensor based on difference frequency mixing of diode lasers in quasi-phasematched LiNbO3.
abstract: A compact, portable and robust room temperature CH4 sensor is reported. By difference frequency mixing a 500 mW alpha-DFB diode laser at 1066 nm and an erbium-doped fiber amplified 1574 nm DFB diode laser in periodically poled lithium niobate up to 7 (mu)W of narrowband radiation at 3.3 microns is generated. Real-time monitoring of CH4 over a 7 day period using direct absorption in an open-path multipass cell (L = 36 m) demonstrates a detection precision of  +/- 14 ppb.
authors.affiliation: Rice Quantum Institute, Rice University, Department of Electrical and Computer Engineering, Houston, TX 77005-1892, USA. davelanc@rice.edu
authors.forename: D G
authors.initials: DG
authors.lastname: Lancaster
authors.forename: R
authors.initials: R
authors.lastname: Weidner
authors.forename: D
authors.initials: D
authors.lastname: Richter
authors.forename: F K
authors.initials: FK
authors.lastname: Tittel
authors.forename: J
authors.initials: J
authors.lastname: Limpert
mesh_terms: D002138:Calibration; D004784:Environmental Monitoring / Q000295:instrumentation*; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D005336:Fiber Optic Technology; D007834:Lasers; D008697:Methane / Q000032:analysis*; D009556:Niobium / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013057:Spectrum Analysis; D013997:Time Factors
chemical_list: D010087:Oxides; D009556:Niobium; C091692:lithium niobate; D008697:Methane