DOCTORAL CANDIDATE 2

The problem of uneven water background absorption in the “protein range” from 1700-1500 cm-1 will be tackled by DC2. Most sensitive mid-infrared photodetectors suffer from saturation effects at large laser powers, which strongly limits their usable dynamic rage. This prevents a precise measurement of small and large signals with the same waveguide and detector. In the first step of this project, the DC will develop high-speed carrier transport optimized interband cascade detectors, which provide both high sensitivity and high saturation power levels to improve the dynamic range. In a second step, an array of these detectors will be used for simultaneous absorption measurements using varying optical path lengths to gain a higher SNR in spectral regions with very strong or very low background water absorption. Mid-IR planar waveguide with multiple channels will be fabricated in cooperation with DC1 and DC9. Advanced coupling strategies will be investigated for parallel beam coupling to the photodetector array, including metamaterial couplers and on-chip hybrid integration. DC2 would perform protein sensing experiments using different solvents, protein concentrations, and temperatures to validate the on-chip device. BSA and Whey proteins would be used as standard examples.