Alexander Lochbaum's Article on Front Cover in ACS Photonics
The article On-Chip Narrowband Thermal Emitter for Mid-IR Optical Gas Sensing by Alexander Lochbaum et. al. demonstrate a CMOS-compatible mid-infrared emitter with applications in the field of low-cost, optical, gas sensing.
Efficient light sources compatible to complementary metal oxide semiconductor (CMOS) technology are key components for low-cost, compact mid-infrared gas sensing systems. In this work we present an on-chip narrowband thermal light source for the mid-infrared wave-length range by combining microelectromechanical system (MEMS) heaters with metamaterial perfect emitter structures.
Exhibiting a resonance quality factor of 15.7 at the center wavelength of 3.96 μm and an emissivity of 0.99, the demonstrated emitter is a spectrally narrow and efficient light source. We show temperature-stable (resonance wavelength shift 0.04 nm/°C) and angular-independent emission characteristics up to angles of 50° and provide an equivalent circuit model illustrating the structure’s resonance behavior. Owing to its spectrally tailored, nondispersive emission, additional filter elements in a free-space optical gas sensing setup become obsolete. In a proof-of-concept demonstration of such a filter-free gas sensing system with CO2 concentrations in the range of 0−50000 ppm, we observe a 5-fold increase in relative sensitivity compared to the use of a conventional blackbody emitter. Our light source is fully compatible with standard CMOS processes and tunable in emission wavelength through the mid-infrared wavelength band. It paves the way for a new class of highly integrated, low-cost optical gas sensors.
Alexander Lochbaum, Yuriy Fedoryshyn, Alexander Dorodnyy, Ueli Koch, Christian Hafner and Juerg Leuthold, ACS Photonics, 4 (6): 1371-1380, Washington, DC: American Chemical Society, 2017. DOI Research Collection