In this talk, I will present my works on theoretical photonics, which spans both practical applications and fundamental analysis. 

First, I will talk about nonlocal metasurfaces based on Fano resonances. I will discuss several unusual applications, including all-optical edge direction, free-space squeezing, and the generation of light bullets. 

Second, I will discuss Lorentz reciprocity's constraints on reflection. It is well-known that reciprocity imposes direct constraints on transmission, absorption, and emission. Here I reveal that Lorentz reciprocity also imposes constraints on reflection. 

Third, I will talk about unitary control of absorption and emission. Unitary control changes the optical absorption and emission of an object by transforming the external photonic modes. It has broad applications and underlies coherent perfect absorption. Yet two basic questions remain unanswered: Given an object, what absorptivity, emissivity, and their difference are attainable via unitary control? How to obtain given absorptivity, emissivity, and their difference? We answer both questions using the mathematics of majorization. 

Biography

Cheng Guo received his Ph.D. in Applied Physics from Stanford University and B.S. in Physics from Peking University. He is now a postdoc with Prof. Shanhui Fan. His research interests are in photonics and optoelectronics, spanning fundamental research including theoretical photonics and topological materials to applications in imaging, sensing, computing, energy, and quantum. He has more than 60 publications (30 first-authored), which have been cited more than 3800 times in total.