Performance characteristics of narrow linewidth fiber laser pumped mid-IR difference frequency mixing light source for methane detection.
A high-power, narrow-linewidth Yb fiber laser with a fiber Bragg grating (FBG) pumped difference frequency generation (DFG) in a periodically poled lithium niobate (PPLN) crystal was investigated in detail. A mid-IR power of approximately 2.3 microW at 3.3 micrometers with a slope efficiency of 0.85 mW/W2 was achieved. A Doppler-broadened absorption spectrum of CH4 at 3038.497 cm-1 (3.2911 micrometers) was obtained with a 0.1-m long-gas cell at a pressure of 133 Pa. The linewidth of the DFG source was evaluated to be less than 96 MHz from the observed spectral linewidth. Real-time monitoring of CH4 (approximately 1.78 ppm) in ambient air in a multipass cell which has an optical path length of 10 m was also demonstrated.
Ashizawa
Hiroaki
H
Department of Physics, School of Science, Tokai University, Hiratsuka, Kanagawa, Japan.
Ohara
Shinobu
S
Yamaguchi
Shigeru
S
Takahashi
Masao
M
Endo
Masamori
M
Nanri
Kenzo
K
Fujioka
Tomoo
T
Tittel
Frank K
FK
D000388:Air / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D005069:Evaluation Studies as Topic; D007834:Lasers; D008697:Methane / Q000032:analysis*; D009556:Niobium; D010087:Oxides; D013055:Spectrophotometry, Infrared; D015018:Ytterbium
D010087:Oxides; D009556:Niobium; C091692:lithium niobate; D015018:Ytterbium; D008697:Methane