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Updated: Jan 11, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Intermodal four-wave mixing in silicon core fibers: enabling versatile wavelength conversion in the mid-infrared
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Highly nonlinear silicon core fibers (SCFs) that offer extended mid-infrared transmission provide a unique platform for efficient wavelength conversion within the 3-5 μm atmospheric window of use for free-space communications and remote sensing. Here, we numerically explore an intermodal four-wave mixing (FWM) scheme that allows for wide spectral translation using large, few-micron-sized-diameter SCFs, well-suited for transmitting the newly generated long-wavelength light. This scheme can be implemented in practical all-fiber devices using tapered nanospike couplers, enabling compact and integrated systems. Benefitting from the unique feature of intermodal zero dispersion, we predict that using only a 25 mm long SCF, it is possible to achieve wide conversion bandwidths (>300 nm) and very high efficiencies (2-15%) when pumped with a single fiber-based source at 1.95 μm. The all-fiber conversion scheme eliminates the need for bulky pump sources and mode converters, showcasing the unique advantages of SCFs for wide-ranging mid-infrared applications.
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