Jan. 11: Multispectral Sensing and Imaging: Integrated RF, THz and Optical Apertures with Dr. Niru Nahar

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Speaker: Dr. Niru K. Nahar, ElectroScience Laboratory

Date: Tuesday, January 11, 2011 at 10:30am

Location: ElectroScience Laboratory Classroom, 1320 Kinnear Rd., Columbus, OH, 43212

Abstract:
RF and microwave signals have enabled prolific applications in major information technologies, such as wireless communications, satellite links, and radars. As such, they enable countless everyday applications such as cell-phones, wireless internet, orbital and land-based remote sensing, and even non-destructive biomedical imaging. The ability to control or shift the phase of the RF signal is essential for processing and agility, however, it is not straightforward to achieve. Specifically, wideband phased-arrays (PAs) require excitations with tunable time-delays for each array element so that the broadband signal experiences phase-shifts proportional to the frequency. This is very difficult to obtain using electronic circuits, but it is quite straightforward using photonics. Namely, the RF signal can be piggy-backed onto an optical wave travelling through an optical fiber. This optical signal can then be delayed in time allowing for squint-free beam steering of RF/ microwave PAs that have wide frequency bandwidth. Moreover, this approach results in compact and lightweight PAs that are not prone to electromagnetic interference. The concept of a hybrid ElectroOptic (EO)-RF communications system is the subject of constant research for over three decades. However, having an integrated and conformal RF-EO platform has not yet been realized. Although RF technology for sensors is relatively mature (albeit mostly narrowband) they are much bulkier compared to typical optical sensors. It is therefore obvious that RF sensors should provide a suitable physical foundation for integrating RF/Optical imaging apertures and sensing devices. This talk will highlight ongoing research in the areas of integrated optical, THz (the least unexplored spectrum) and RF apertures that will offer multiple sensor and processing modalities in a single common aperture. With this approach, RF reconfiguration can be enabled for multi-spectral wide area sensing to provide “single look” imaging. Subsequently, the EO can be used as necessary to focus on small areas for high resolution imaging. Concurrently, THz sensors can cover the spectral range in between, for various sensing and imaging, as well as communications scenarios.

Speaker's bio:
Dr. Niru K. Nahar received her MS and PhD degrees in Electrical and Computer Engineering from The Ohio State University in 2002 and 2008, respectively. Her PhD research focuses on wideband phased antenna arrays with optical true time delay engine for beam scanning. Currently, she is a Post-Doctoral researcher at ElectroScience Laboratory. Her recent research is focused on designing integrated RF-EO multiband sensors and frequency selective surface filters for optical and THz sensing. Dr. Nahar also holds a MS degree in physics from Indiana University of Pennsylvania, Indiana, PA and has her B.Sc. (honors) in physics from the Dhaka University, Bangladesh. Her MS thesis work involved Near IR photodetectors. She was a graduate research intern at Osram Sylvania Inc., Chemical and Metallurgical Division, in the Surface Analysis Laboratory for a year where she focused on the analysis of both inorganic and organic materials with FTIR, ESCA, AES, SNMS and Raman Spectroscopy. In addition, Dr. Nahar has several years of experience working in the optometry and vision sciences area.