Light is a powerful tool for the analysis of chemical and biological species in complex environments. Traditional optical sensors are bulky, costly instruments often involving mechanical moving parts, which severely limits their deployment in practical applications. Photonic integration offers a solution to miniaturize optical sensors into a rugged, chip-scale platform that can be mass produced using mature microfabrication techniques in the same manner as electronic chips. On-chip integration further provides unprecedented flexibility in implementing novel device designs, which naturally gives rise to the question: what makes the best chip-scale photonic sensor?
In this talk, we will provide a detailed account regarding the design rationales of different essential components of a photonic sensing system: the sensing element, the light source, and the light analyzer. Specifically, I will start by discussing our recent theoretical work that resolves a longstanding controversy over the optimal waveguide sensor design . I will then introduce digital Fourier Transform (dFT) spectroscopy, a chip-scale spectrometer technology offering superior performance and scalability ideally suited for on-chip photonic sensing . Lastly, I will review our work on integration of on-chip supercontinuum sources with waveguide sensors towards a fully-integrated, miniaturized spectroscopic sensing system .
 D. Kita, J. Michon, S. G. Johnson, and J. Hu, "Are slot and sub-wavelength grating waveguides better than strip waveguides for sensing?" Optica 5, 1046-1054 (2018).
 D. Kita, B. Miranda, D. Favela, D. Bono, J. Michon, H. Lin, T. Gu, and J. Hu, "High-performance and scalable on-chip digital Fourier transform spectroscopy," Nat. Commun. 9, 4405 (2018).
 Q. Du, Z. Luo, H. Zhong, Y. Zhang, Y. Huang, T. Du, W. Zhang, T. Gu, and J. Hu, "Chip-scale broadband spectroscopic chemical sensing using an integrated supercontinuum source in a chalcogenide glass waveguide," Photon. Res. 6, 506-510 (2018).
Bio: Juejun (JJ) Hu received his B.S. from Tsinghua University, China, in 2004, and his Ph.D. from Massachusetts Institute of Technology (MIT), USA, in 2009, both in materials science and engineering. He is currently an associate professor at MIT’s Department of Materials Science and Engineering. Prior to joining MIT, he was an Assistant Professor at the University of Delaware, USA from 2010 to 2014. Dr. Hu has authored and coauthored more than 90 refereed journal publications and has been recognized with the National Science Foundation Faculty Early Career Development award, the Robert L. Coble Award from the American Ceramic Society, the SPIE Early Career Achievement Award, the DARPA Young Faculty Award, the Gerard J. Mangone Young Scholars Award, the University of Delaware College of Engineering Outstanding Junior Faculty Member, and the University of Delaware Excellence in Teaching Award, among others.