Broadband Spectrometer For Ultrasensitive Detection Using Plasmonic Hyperbolic Metamaterials

There are many applications which require high sensitivity spectral detection. In some cases, you need the wavelength range to be extended to cover all necessary spectral fingerprints. We are proposing a broadband spectrometer for ultrasensitive detection based on plasmonic hyperbolic metamaterials and diffraction gratings. Using variety of materials in fabrication of the hyperbolic metamaterials, we can cover the wide spectral range from near UV (similar to 250 nm) to IR (similar to 2 mu m). In our spectrometer, the diffraction gratings have two functions. One is coupling the incident light source with the plasmonic guiding modes, which have a very high effective refractive index (>= 8.1), much higher than the refractive index of germanium (4.05), the natural material with the highest refractive index. While a prism can also be used for coupling guiding modes with incident light, a diffraction grating is the only way to excite the guiding modes because of the plasmonics modes with very high effective refractive index. The second function of the diffraction gratings is their natural role in spectrometers. We demonstrated based on numerical simulations that we could reach high detection spectral sensitivity using compact diffraction gratings combined with hyperbolic metamaterials; the huge "n-meter" spectrometer is not necessary.