Ultracompact Spectrometers for Infrared Wavelengths

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Abstract TitleUltracompact Spectrometers for Infrared WavelengthsNontechnical Abstract:Infrared (IR) spectroscopy has attracted significant attention due to broad applications in this spectral range including thermal imaging, chemical sensing, environmental monitoring, medical imaging, security systems, atmospheric studies, and high-speed electronics. Almost all molecules exhibit absorption resonance in the IR wavelength region from 6 to 16 micrometers. These resonances are unique to each molecule and are called molecular “fingerprints”, which can be used to identify chemical species. The goal of this project is to create an ultracompact spectrometer (UCS) which can be integrated on a chip. Unlike traditional benchtop spectrometers, such tiny devices enable integration with size-limited systems, such as drones, portable devices, and field-deployable devices. They provide a low-cost and efficient method for chemical sensing and environmental monitoring. For example, a drone containing UCSs can be used for chemical analysis to detect environmental toxins. Field-deployable devices can be used in a city, farm, or forest for volatile organic compound sensing. This project will also work with the University of Delaware (UD) College of Engineering Outreach office to create short videos explaining fundamental concepts in optics aimed at middle schoolers. The goal of these videos is to introduce students to optics, a subject that they do not see in middle school in Delaware, but which is interesting and does not require advanced math to understand. The videos will be distributed on a wide range of social media platforms, allowing us to reach a large audience. The videos will link to additional scientific information from, for example, the Optical Society of America as well as information on attending UD. Technical Abstract:Conventional IR spectroscopy systems are expensive, bulky, and require mechanical motion. Their operation principle makes it impossible to significantly shrink their size. This project aims to employ novel engineered materials and advanced nanofabrication to create an ultracompact IR spectrometer (UCS) on-a-chip. Specifically, this project will use gradient permittivity materials such as heavily-doped indium arsenide to perform both spectral splitting and subwavelength light confinement. By integrating gradient permittivity materials and detector arrays on a chip, the proposed UCS eliminates complex optical elements and shrinks the dimensions of the design to as small as 10 micrometers. The proposed UCS is an innovative way to collect spectral information at the nanoscale and significantly reduces the size and cost of a spectrometer. Unique growth approaches and nano-fabrication procedures will be developed, advancing knowledge in the field of materials science and the integration of nano-devices. The results of this project can be applied to a wide range of other optoelectronic devices requiring subwavelength focusing and wavelength demultiplexing, advancing understanding across a range of fields.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.