Lancaster, D.Richter, D.Tittel, F.2010-08-172010-08-171999Applied Physics B: Lasers and Optics, 1999; 69(5-6):459-4650946-21711432-0649http://hdl.handle.net/2440/59849Tunable narrowband mid-infrared radiation from 3.25 to 4:4 mm is generated by a compact fiber-coupled, difference-frequency-based spectrosopic source. A 20-mW external cavity diode laser (with a tuning range from 814 to 870 nm) and a 50-mW distributed-Bragg-reflector diode-laser- seeded ytterbium-doped fiber amplifier operating at 1083 nm are difference-frequency mixed in a multi-grating, temperature-controlled periodically poled LiNbO3 crystal. A conversion efficiency of 0:44mW/(W₂cm) (corresponding to a power of ≈3 μW at 3:3 μm) represents the highest conversion efficiency reported for a portable device. Performance characteristics of such a sensor and its application to spectroscopic detection of CO2, N2O, H2CO, HCl, NO2, and CH4 will be reported in this work.enCopyright Springer-Verlag 1999Journal article003000115010.1007/s00340005083565156