Theory for Twisted Bilayer Photonic Crystal Slabs.
Physical review letters
2021; 126 (13): 136101
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
Determining the optimal learning rate in gradient-based electromagnetic optimization using the Shanks transformation in the Lippmann-Schwinger formalism
2020; 45 (3): 595–98
In gradient-based optimization of photonic devices, within the overall design parameter space, one iteratively performs a line search in a one-dimensional subspace as spanned by the search direction. While the search direction can be efficiently determined with the adjoint variable method, there has not been an efficient algorithm that determines the optimal learning rate that controls the distance one moves along the search direction. Here we introduce an efficient algorithm of determining the optimal learning rate, using the Shanks transformation in the Lippmann-Schwinger formalism. Our approach can determine very accurately the optimal learning rates at each epoch, with only a modest increase of computational cost. We show that this approach can significantly improve the figure of merits of the final structure, as compared to conventional methods for estimating the learning rate.
View details for DOI 10.1364/OL.379375
View details for Web of Science ID 000510869500001
View details for PubMedID 32004260
Penetration Depth Engineering in Plasmonic Metafilms for Enhanced Reflection and Confinement
View details for Web of Science ID 000612090000453
Near-complete violation of Kirchhoff's law of thermal radiation with a 0.3 T magnetic field
2019; 44 (17): 4203–6
The capability to overcome Kirchhoff's law of thermal radiation provides new opportunities in energy harvesting and thermal radiation control. Previously, design towards demonstrating such capability requires a magnetic field of 3 T, which is difficult to achieve in practice. In this work, we propose a nanophotonic design that can achieve such capability with a far more modest magnetic field of 0.3 Tesla, a level that can be achieved with permanent magnets. Our design uses guided resonance in low-loss dielectric gratings sitting on a magneto-optical material, which provides significant enhancement on the sensitivity to the external magnetic field.
View details for DOI 10.1364/OL.44.004203
View details for Web of Science ID 000483918900029
View details for PubMedID 31465363
- Penetration Depth Reduction with Plasmonic Metafilms ACS PHOTONICS 2019; 6 (8): 2049–55
- Accelerating adjoint variable method based photonic optimization with Schur complement domain decomposition OPTICS EXPRESS 2019; 27 (15): 20711–19
- High Reflection from a One-Dimensional Array of Graphene Nanoribbons ACS PHOTONICS 2019; 6 (2): 339–44
High Reflection from a One-Dimensional Array of Graphene Nanoribbons
View details for Web of Science ID 000482226301492
- Accelerating convergence of iterative solution of finite difference frequency domain problems via schur complement domain decomposition OPTICS EXPRESS 2018; 26 (13): 16925–39