Room-temperature channel waveguide device for the detection of atmospheric methane

Summary form only given. Devices based on difference-frequency generation (DFG) in channel waveguides are an attractive alternative to cryogenically cooled lasers for the production of tunable, narrowband radiation in the mid-infrared. In previous work we described such a device, incorporating a periodically segmented taper to ensure single-mode excitation of the waveguide, which was used to detect atmospheric water vapor at 2.8 /spl mu/m. In the present work, we demonstrate that a device with similar conversion efficiency can be designed for operation at the longer wavelengths (near 3.3 /spl mu/m) required for the detection of atmospheric methane. In addition, we demonstrate that a solid taper can be used in place of the periodically segmented taper to ensure single-mode operation.