Continuous-wave mid-infrared radiation near 3.5µm is generated by difference-frequency mixing of the output of a compact 1.1–1.5-µm dual-wavelength fiber amplifier in periodically poled LiNbO<sub>3</sub> . The diode side-pumped amplifier is constructed with double-cladding Yb-doped fiber followed by single-mode Er/Yb codoped fiber. Output powers of as much as 11µW at 3.4µm are obtained, and spectroscopic detection of CH<sub>4</sub> and H<sub>2</sub>CO is demonstrated.
© 1998 Optical Society of America
(060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
(190.2620) Nonlinear optics : Harmonic generation and mixing
(280.3420) Remote sensing and sensors : Laser sensors
(300.6340) Spectroscopy : Spectroscopy, infrared
L. Goldberg, J. Koplow, D. G. Lancaster, R. F. Curl, and F. K. Tittel, "Mid-infrared difference-frequency generation source pumped by a 1.1–1.5- m dual-wavelength fiber amplifier for trace-gas detection," Opt. Lett. 23, 1517-1519 (1998)