Monolithic Photonic Crystal On-Chip Spectrometer for Laser Absorption Spectroscopy

This Small Business Innovation Research Phase I project aims at developing a commercially viable, 50 micron long lab-on-chip photonic crystal monolithically integrated, light-weight and easily portable infrared spectrometer for diode laser absorption spectroscopy of chemical warfare simulant triethylphosphate. Defect engineered photonic crystals, with sub micron dimensions have already demonstrated high sensitivity to trace volumes of analytes; however exact identification of analyte through spectroscopic signatures has not been demonstrated. Our device provides a factor of 2000 reduction in optical interaction length with the analyte compared to conventional waveguides leading to enhanced optical absorption by analytes in the optical path. By measuring absorption differences in presence and absence of triethylphosphate, presence of triethylphosphate is determined. The fabrication platform ensures easy monolithic integration of infrared lasers, detectors and spectrometer with high volume and low cost production. Our device is light-weight and miniature, and allows easy portability and extremely versatile. Our technology can be extended to spectroscopy of any gas in multiple application areas and markets.