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SWIR Spectroscopic Sensing Using RCE Detectors

Activity: Talk or presentation typesOral presentation


Growing a detector within a resonant cavity blocks light of most wavelengths from entering the absorber and produces a device with high spectral selectivity and low spectral bandwidth, of the order of 50 nm, at a chosen wavelength. These characteristics make such a device a prime candidate for sensing absorption peaks, such as CO2 at 2.05 μm or CH4 at 3.3 μm. They could also be used within new wearable devices, to monitor the concentrations of biomarkers within a person’s body.
As well as blocking light at unwanted wavelengths, the absorption of light is increased at the peak wavelength due to an enhanced optical field in the absorber, at this wavelength. This allows the thickness of the absorber to be significantly reduced with a commensurate reduction in the leakage currents. Therefore, the high quantum efficiency and low leakage current result in an enhanced signal to noise ratio compared to conventional detectors.
We report resonant cavity detectors grown to the structure shown in figure 1, with peak resonance wavelength response at 2.15 μm. The leakage currents are measured to be lower than comparative non-resonant detectors. The potential for their use in health targeted infrared spectroscopy is shown through measurements on glucose solutions, see figure 2. In human blood, there is of the order of 0.1 % glucose and the results show even this small concentration can be resolved with this detector.

Event (Conference)

TitleUK Semiconductors 2019
LocationSheffield Hallam University
CountryUnited Kingdom
Degree of recognitionNational event