Cheng-Wei Qiu
National University of Singapore
chengwei.qiu@nus.edu.sg

Speaker’s Biography:
Cheng-Wei Qiu is Fellow of APS, Optica, SPIE and The Electromagnetics Academy, US. He is the recipient of President’s Science Award 2023, the highest science distinction in Singapore. He was elected Fellow of ASEAN Academy of Engineering and Technology. He is well known for his research in structured light and interfaces. He has published over 580 peer-reviewed journal papers. He was the recipient of URSI Young Scientist Award in 2008, NUS Young Investigator Award in 2011, MIT TR35@Singapore Award in 2012, Young Scientist Award by Singapore National Academy of Science in 2013, Faculty Young Research Award in NUS 2013, SPIE Rising Researcher Award 2018, Young Engineering Research Award 2018, and Engineering Researcher Award 2021 in NUS, and World Scientific Medal 2021 by Institute of Physics, Singapore, Achievement in Asia Award (Robert T. Poe Prize) by International Organization of Chinese Physicists and Astronomers in 2022. He was Highly Cited Researchers in 2019, 2020, 2021, 2022, 2023 by Web of Science. As an overseas partner, he has been awarded China’s Top 10 Optical Breakthroughs for 5 times (2019, 2020, 2021(one in Fundamental Research, and one in Applied Research), 2023). He has been serving in Associate Editor for various journals such as JOSA B, PhotoniX, Photonics Research, and Editor-in-Chief for eLight. He also serves in Editorial Advisory Board for Laser and Photonics Review, Advanced Optical Materials, and ACS Photonics.

Speech title: Vectorial, Filter-less, Full-Stokes and High-dimensional Metasurface Photodetectors

Abstract:
Mid-infrared detectors are of critical importance for a variety of applications including thermal imaging, spectrometer, sensing and free space communication. High sensitivity, zero power consumption, fast response, simple CMOS-compatible fabrication processes, small footprint, wavelength and polarization selectivity are highly desired, while still being elusive so far especially at room temperature. In this talk, we will report a series of metasurface-mediated detectors. Non-centrosymmetric metallic nanoantennas are deployed to break the symmetry of local electromagnetic field and induce directional flow of hot carriers in graphene, leading to large unbalanced mid-IR photoresponse at room temperature without external bias. We demonstrate zero-bias uncooled mid-infrared photodetectors with three orders higher responsivity than conventional bulk photovoltaic effect (BPVE) and a noise equivalent power of 0.12 nW Hz−1/2. We further establish a scheme to realize configurable polarity transition by exploiting the vectorial and non-local photoresponse in hybrid metasurface of nanoantennas and graphene. By tuning the orientation of nanoantennas, polarization ratio (PR) values vary from positive (unipolar regime) to negative (bipolar regime), covering all possible numbers (1 → ∞/−∞ → −1). Polarization-angle perturbation down to 0.03° Hz−1/2 in the mid-infrared range is demonstrated. We will also report on-chip filterless photodetectors in mid-infrared which solely responds to circular polarizations. We finally showcase how machine learning could enable be full-Stokes photodetection and high-dimensional sensing of light’s properties.