Infrared Photonic Crystal Spectrometer for the Cryovacuum Environment

The proposed innovation is a compact infrared photonic crystal spectrometer. The photonic crystal spectrometer utilizes the leaky modes of photonic crystals patterned on a multimode waveguide to selectively extract wavelength specific light to a 2D detector array (e.g. an imager). The pattern detected by the imager can then be analyzed to reconstruct the spectrum. Significant differences between this technology and diffractive grating technologies are that the photonic crystals can be arrayed over two dimensions, the patterned regions are small allowing a single detector to image many patterns, and the spectrometer resolution is independent of the distance between the diffractive element and the detector. Unlike a Fourier transform infrared spectrometer, the photonic crystal spectrometer has no moving parts. These characteristics also yield a spectrometer with the potential for high vacuum, low temperature, vibration, and particle tolerance. The scaling law that governs this system enables substantial miniaturization of these spectrometer devices; the resulting module size is constrained by the dimensions of the detector. BENEFIT: Applications of this project include portable infrared spectrometer modules for absorption analysis of organic and inorganic compounds. Spectrophotometer implementations of such modules could be used for detection of pollutants, toxins, and chemicals for environmental, public health, safety, and law enforcement applications.