Beicheng Lou

All Publications

• Free-Space Beam Steering with Twisted Bilayer Photonic Crystal Slabs ACS PHOTONICS Lou, B., Tang, H., Du, F., Gao, G., Mazur, E., Fan, S. 2024

  View details for DOI 10.1021/acsphotonics.4c00736

  View details for Web of Science ID 001280000400001

• Three-Dimensional Reconfigurable Optical Singularities in Bilayer Photonic Crystals. Physical review letters Ni, X., Liu, Y., Lou, B., Zhang, M., Hu, E. L., Fan, S., Mazur, E., Tang, H. 2024; 132 (7): 073804

  Abstract

  Metasurfaces and photonic crystals have revolutionized classical and quantum manipulation of light and opened the door to studying various optical singularities related to phases and polarization states. However, traditional nanophotonic devices lack reconfigurability, hindering the dynamic switching and optimization of optical singularities. This paper delves into the underexplored concept of tunable bilayer photonic crystals (BPhCs), which offer rich interlayer coupling effects. Utilizing silicon nitride-based BPhCs, we demonstrate tunable bidirectional and unidirectional polarization singularities, along with spatiotemporal phase singularities. Leveraging these tunable singularities, we achieve dynamic modulation of bound-state-in-continuum states, unidirectional guided resonances, and both longitudinal and transverse orbital angular momentum. Our work paves the way for multidimensional control over polarization and phase, inspiring new directions in ultrafast optics, optoelectronics, and quantum optics.

  View details for DOI 10.1103/PhysRevLett.132.073804

  View details for PubMedID 38427898

• Experimental probe of twist angle-dependent band structure of on-chip optical bilayer photonic crystal. Science advances Tang, H., Lou, B., Du, F., Zhang, M., Ni, X., Xu, W., Jin, R., Fan, S., Mazur, E. 2023; 9 (28): eadh8498

  Abstract

  Recently, twisted bilayer photonic materials have been extensively used for creating and studying photonic tunability through interlayer couplings. While twisted bilayer photonic materials have been experimentally demonstrated in microwave regimes, a robust platform for experimentally measuring optical frequencies has been elusive. Here, we demonstrate the first on-chip optical twisted bilayer photonic crystal with twist angle-tunable dispersion and great simulation-experiment agreement. Our results reveal a highly tunable band structure of twisted bilayer photonic crystals due to moiré scattering. This work opens the door to realizing unconventional twisted bilayer properties and novel applications in optical frequency regimes.

  View details for DOI 10.1126/sciadv.adh8498

  View details for PubMedID 37436985

• Inverse Design of Optical Switch Based on Bilevel Optimization Inspired by Meta-Learning ACS PHOTONICS Lou, B., Rodriguez, J., Wang, B., Cappelli, M., Fan, S. 2023

  View details for DOI 10.1021/acsphotonics.3c00113

  View details for Web of Science ID 001010294300001

• Tunable guided resonance in twisted bilayer photonic crystal. Science advances Lou, B., Wang, B., Rodríguez, J. A., Cappelli, M., Fan, S. 2022; 8 (48): eadd4339

  Abstract

  We experimentally demonstrate tunable guided resonance in twisted bilayer photonic crystals. Both the numerically and the experimentally obtained transmission spectra feature resonances with frequencies strongly dependent on the twist angle, as well as resonances with frequencies that are largely independent of the twist angle. These resonant features can be well understood with a simple analytic theory based on band folding. Our work illustrates the rich tunable resonance physics in twisted bilayer systems.

  View details for DOI 10.1126/sciadv.add4339

  View details for PubMedID 36449612

• Tunable Frequency Filter Based on Twisted Bilayer Photonic Crystal Slabs ACS PHOTONICS Lou, B., Fan, S. 2022; 9 (3): 800-805

  View details for DOI 10.1021/acsphotonics.1c01263

  View details for Web of Science ID 000776221600011

• Hyperbolic Jigsaws and Families of Pseudomodular Groups II INTERNATIONAL MATHEMATICS RESEARCH NOTICES Lou, B., Tan, S., Anh Duc Vo 2021

  View details for DOI 10.1093/imrn/rnab164

  View details for Web of Science ID 000756393400001

• Inverse Design of Plasma Metamaterial Devices for Optical Computing PHYSICAL REVIEW APPLIED Rodriguez, J. A., Abdalla, A. I., Wang, B., Lou, B., Fan, S., Cappelli, M. A. 2021; 16 (1)

  View details for DOI 10.1103/PhysRevApplied.16.014023

  View details for Web of Science ID 000678050500004

• Theory for Twisted Bilayer Photonic Crystal Slabs. Physical review letters Lou, B., Zhao, N., Minkov, M., Guo, C., Orenstein, M., Fan, S. 2021; 126 (13): 136101

  Abstract

  We analyze scattering properties of twisted bilayer photonic crystal slabs through a high-dimensional plane wave expansion method. The method is applicable for arbitrary twist angles and does not suffer from the limitations of the commonly used supercell approximation. We show strongly tunable resonance properties of this system which can be accounted for semianalytically from a correspondence relation to a simpler structure. We also observe strongly tunable resonant chiral behavior in this system. Our work provides the theoretical foundation for predicting and understanding the rich optical physics of twisted multilayer photonic crystal systems.

  View details for DOI 10.1103/PhysRevLett.126.136101

  View details for PubMedID 33861130

• Wide wavelength-tunable narrow-band thermal radiation from moire patterns APPLIED PHYSICS LETTERS Guo, C., Guo, Y., Lou, B., Fan, S. 2021; 118 (13)

  View details for DOI 10.1063/5.0047308

  View details for Web of Science ID 000636372600002

• Inverse Design of Photonic Crystals through Automatic Differentiation ACS PHOTONICS Minkov, M., Williamson, I. D., Andreani, L. C., Gerace, D., Lou, B., Song, A. Y., Hughes, T. W., Fan, S. 2020; 7 (7): 1729–41

  View details for DOI 10.1021/acsphotonics.0c00327

  View details for Web of Science ID 000551497000020