SBIR Phase II: Photonic Crystal Coherent Thermal Emission for Sensors

This SBIR Phase II project proposes to fabricate a photonic crystal, thermal mid-IR source with low divergence and low dispersion at about 0.1% the cost of competing technologies. Phase I research resolved fine structure of the emission spectrum from 2-D photonic crystals showing that the high intensity, large bandwidth peak had many submodes with strong polarization and angular dependence. In a series of designed experiments the intensity and central wavelength of these submodes were varied with geometrical alterations of the photonic crystal, and theoretically were correlated to surface plasmon resonances. A computer model was developed that matched experimental data. Results imply optimization of photonic crystal structure in Phase II could isolate a single sub-mode resulting in very low dispersion, very low divergence emission that could be coherent. The project will support high-end computational research at a university for complex electro-magnetic modeling of photon - surface plasmon interactions. Improved structures predicted by these calculations will be fabricated at an NSF supported nano-fabrication facility. We will examine effects of altered symmetry, periodic defects, and detailed shaping of electrostatic fields. All existing choices for coherent radiation in the mid-infrared spectral region are too expensive for widespread vapor detection. Examples are wavelength shifting of high power pulsed lasers using non-linear optical effects or quantum cascade lasers (now $5,000 each). The proposed source could sell for less than $10. Additionally, it could significantly reduce the cost of sensitive spectroscopic instrumentation allowing detection of vapors well below 1ppm concentration and application to widespread use as toxic vapor detectors for commercial, residential, and homeland defense applications. Compared to other technology, these detectors are temperature insensitive, rugged, and free of interference effects with zero maintenance and zero drift. This work will contribute towards understanding photon surface plasmon interactions within 2D photonic crystals. The field has huge implications for the microelectronics and optics industry as optical and electronic functions are combined onto single chips for applications to optical computing, communications, etc.