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Garg P, Lamprianidis AG, Beutel D, Karamanos T, Verfürth B, Rockstuhl C. Modeling four-dimensional metamaterials: a T-matrix approach to describe time-varying metasurfaces. OPTICS EXPRESS 2022; 30:45832-45847. [PMID: 36522979 DOI: 10.1364/oe.476035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 11/09/2022] [Indexed: 06/17/2023]
Abstract
Exploring the interaction of light with materials periodically structured in space and time is intellectually rewarding and, simultaneously, a computational challenge. Appropriate computational tools are urgently needed to explore how such upcoming photonic materials can control light on demand. Here, we introduce a semi-analytical approach based on the transition matrix (also known as T-matrix) to analyze the optical response of a spatiotemporal metasurface. The metasurface consists of a periodic arrangement of time-varying scattering particles. In our approach, we depart from an individual scatterer's T-matrix to construct the effective T-matrix of the metasurface. From that effective T-matrix, all observable properties can reliably be predicted. We verify our semi-analytical approach with full-wave numerical simulations. We demonstrate a speed-up with our approach by a factor of more than 500 compared to a finite-element simulation. Finally, we exemplify our approach by studying the effect of time modulation on a Huygens' metasurface and discuss some emerging observable features.
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Jaffray W, Belli F, Carnemolla EG, Dobas C, Mackenzie M, Travers J, Kar AK, Clerici M, DeVault C, Shalaev VM, Boltasseva A, Ferrera M. Near-zero-index ultra-fast pulse characterization. Nat Commun 2022; 13:3536. [PMID: 35725983 PMCID: PMC9209551 DOI: 10.1038/s41467-022-31151-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 06/06/2022] [Indexed: 11/19/2022] Open
Abstract
Transparent conducting oxides exhibit giant optical nonlinearities in the near-infrared window where their linear index approaches zero. Despite the magnitude and speed of these nonlinearities, a “killer” optical application for these compounds has yet to be found. Because of the absorptive nature of the typically used intraband transitions, out-of-plane configurations with short optical paths should be considered. In this direction, we propose an alternative frequency-resolved optical gating scheme for the characterization of ultra-fast optical pulses that exploits near-zero-index aluminium zinc oxide thin films. Besides the technological advantages in terms of manufacturability and cost, our system outperforms commercial modules in key metrics, such as operational bandwidth, sensitivity, and robustness. The performance enhancement comes with the additional benefit of simultaneous self-phase-matched second and third harmonic generation. Because of the fundamental importance of novel methodologies to characterise ultra-fast events, our solution could be of fundamental use for numerous research labs and industries. Frequency resolved optical gating is the core method for characterising ultra-fast optical pulses. Here, the authors use zero-index nonlinearities to largely enhance key performances and enable simultaneous second and third harmonic measurements.
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Affiliation(s)
- Wallace Jaffray
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, SUPA, Edinburgh, EH14 4AS, UK
| | - Federico Belli
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, SUPA, Edinburgh, EH14 4AS, UK
| | - Enrico G Carnemolla
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, SUPA, Edinburgh, EH14 4AS, UK
| | - Catalina Dobas
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, SUPA, Edinburgh, EH14 4AS, UK
| | - Mark Mackenzie
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, SUPA, Edinburgh, EH14 4AS, UK
| | - John Travers
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, SUPA, Edinburgh, EH14 4AS, UK
| | - Ajoy K Kar
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, SUPA, Edinburgh, EH14 4AS, UK
| | - Matteo Clerici
- James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Clayton DeVault
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Vladimir M Shalaev
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Alexandra Boltasseva
- School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Marcello Ferrera
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, SUPA, Edinburgh, EH14 4AS, UK.
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