Multiwavelength Selective IR Emission Using Surface Plasmon Polaritons for Gas Sensing

Multiwavelength selective infrared (IR) emission utilizing reflection type gratings is proposed. Surface plasmon polariton (SPP) is excited on the metallic grating by IR having the wavelength nearly equal to the grating pitch. The SPP carries IR energy from the thermal source to the outside. The grating element with two different pitches is combined with a single thermal source. Emission peaks at wavelengths corresponding to the pitches are confirmed. CO₂ gas is confirmed to absorb the output IR at the wavelength of an emission peak following the Lambert-Beer law.