Author Affiliations
Abstract
Department of Physics, School of Science, Tokai University, 1117 Kitakaname, Hiratsuka 259-1292, Japan
Development of a fiber laser pumped, compact mid-infrared (IR) difference frequency spectrometer employing a periodically poled LiNbO3 (PPLN) for next generation environmental monitoring is presented. Previous spectroscopic experiments of various gas species, performance characteristics of pump and signal lasers and PPLN-based difference frequency generation (DFG) are reviewed. The DFG spectrometers developed in our facility were carefully calibrated with concentrations between a few ppm and 500 ppm, and demonstrated with an excellent linearity. Moreover, a ratio between measurement deviation and gas concentration was approximately +-1%, which could maintain in a long-term measurement operation (~1000 h). Rapid gas detection for N2O, CH4, CO2, NO2, and NH3 with a total measurement time of less than 10 s was achieved with interference completely free from absorption spectra of other gas species, resulting in minimum detectable concentration at sub ppm level. Also, real-time NO2 monitoring of an exhaust gas of a diesel engine is demonstrated, and a simultaneous dual gas detection concept by the DFG is introduced.
120.6200 Spectrometers and spectroscopic instrumentation 190.2620 Harmonic generation and mixing 280.3420 Laser sensors 300.6340 Spectroscopy, infrared Chinese Optics Letters
2007, 5(s1): 105