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Non-Hermitian Photonics: New Functionality by Symmetry, New Opportunity beyond Symmetry


Professor Liang Feng

Materials Science & Engineering

and Electrical and Systems Engineering

University of Pennsylvania


Date & Time

Tuesday, 5 December 2023

6:00 am


CPD-G.02 Central Podium (Centennial Campus) HKU


A stream of photons is typically topologically trivial, nevertheless, its full-vector nature intrinsically endows light with full capability of creating and carrying unique symmetry and topology, especially non-Hermitian symmetries that cannot be easily implemented in condensed matter. Explorations of symmetry and topology on a photonic platform not only deepen our understanding of fundamental physics, but also facilitate technological breakthroughs. In this seminar, I will present our recent efforts on investigating symmetry and topological physics for the next generation of optical and quantum information technology. We demonstrated the world’s first orbital angular momentum (OAM) microlaser that structures and twists the lasing radiation at the microscale, which can create a high-dimensional spin-orbit Hilbert space to meet the growing demand for information capacity. We conducted a supersymmetry-based formalism to achieve higher-dimensional microlaser phased arrays producing high-radiance, small-divergence laser beams with orders of magnitude enhancement in energy density. Furthermore, by strategically interfacing non-Hermitian photonics and topological physics, we realized the dynamic control of robust topological transmission links of light inside the bulk of a photonic topological insulator, routing optical signals in a highly flexible and scalable manner. Beyond the known quantum symmetry paradigms, we target dynamic control of spatial-temporal modulations of the imaginary index on an active semiconductor platform, realizing a new lithography-free paradigm for integrated photonic processing. Photonic neural networks with extraordinary flexibility have been demonstrated to perform in-situ learning and training with high accuracy.


Liang Feng is a Professor of Materials Science & Engineering (MSE) and Electrical and Systems Engineering (ESE) at the University of Pennsylvania. He received his Ph.D. in Electrical Engineering from UCSD and BS/MS both in Physics from Nanjing University, China. Currently his research interests include integrated photonics, photonic computing/information processing, quantum information science, and optoelectronics. He is an OSA fellow and a recipient of Aspen Institute Italia Award, Sloan Research Fellow, DARPA Director’s Fellowship, DARPA Young Faculty, NSF CAREER, ARO Young Investigator awards, etc.


Research Areas:

Contact for


Prof. X.B. Yin

3910 2659

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