From Free Space to Nanophotonics-integrated Metasurfaces Optics

Pin Chieh Wu^1*

¹Department of Photonics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Pin Chieh Wu, email:pcwu@gs.ncku.edu.tw

There has been plenty of interest and investigation in plasmonic metasurfaces to realize high-performance flat optical components and polarization converter devices [1, 2]. Most reported plasmonic metasurfaces are optimized under the realm of highly-radiative lossy electric and magnetic multipoles, which in fact limit their transmission efficiency [3]. As a result, plasmonic metasurfaces do seem not very ideal for real applications in particular after introducing their dielectric counterparts. Nonetheless, it has been shown that dielectric metasurfaces cannot interact with the incident light as strongly as plasmonic structures. The requirement of a high aspect ratio in dielectric metasurfaces further devaluates their practical applications [4].
In this talk, I will present two strategies to realize high-performance metasurfaces for low-profile optics applications. First, we draw our attention to modifying the model that is commonly used for designing a plasmonic metasurface for decades. We innovate a strategy to enhance the transmission efficiency of plasmonic metasurface to the highest attainable level [5, 6]. By integrating a solid nano-structure with its inverse complementary, we realized a plasmonic metasurface with a circular cross-polarization conversion efficiency higher than 50% in transmission at near-infrared wavelengths. Such high optical performance metasurface is achieved by simultaneously exciting the electric, magnetic, and toroidal multipolar modes, which satisfies the generalized Kerker condition and improves the transmission efficiency. We further demonstrate a couple of metasurface-based components such as a beam deflector and a flat focusing lens with record operating efficiency based on the proposed metasurface. Second, we switch the research topic from free space components to metasurface-integrated devices. We propose that the polarization state of a lasing emission can be actively modulated at the source with a metasurface-engaged microcavity, including highly circularly polarized, linearly polarized, or elliptically polarized lasing emission [7]. Taking advantage of strong optical feedback produced by the Fabry-Perot optofluidic microcavity, light-meta-atoms interactions will be enlarged, resulting in polarized lasing emission with high purity and controllability. These studies provide innovative insights into fundamental optics and laser physics, opening new possibilities by bridging metasurface into microlasers and practical applications.

Reference
1. F. Qin, L. Ding, L. Zhang, et. al., "Hybrid bilayer plasmonic metasurface efficiently manipulates visible light," Sci. Adv. 2, e150116 (2016).
2. N. K. Grady, J. E. Heyes, D. R. Chowdhury, et. al., "Terahertz metamaterials for linear polarization conversion and anomalous refraction," Science 340, 1304-1307 (2013).
3. C. Hou-Tong, J. T. Antoinette, and Y. Nanfang, "A review of metasurfaces: Physics and applications," Rep. Prog. Phys. 79, 076401 (2016).
4. Q. He, S. Sun, S. Xiao, and L. Zhou, "High-efficiency metasurfaces: Principles, realizations, and applications," Adv. Opt. Mater. 6, 1800415 (2018).
5. A. Hassanfiroozi, P.-S. Huang, S.-H. Huang, et. al., "A toroidal-Fano-resonant metasurface with optimal cross-polarization efficiency and switchable nonlinearity in the near-infrared," Adv. Opt. Mater. 9, 2101007 (2021).
6. A. Hassanfiroozi, Y.-C. Cheng, S.-H. Huang, et. al., "Toroidal-assisted generalized Huygens’ sources for highly transmissive plasmonic metasurfaces," Laser & Photonics Reviews 16, 2100525 (2022).
7. Z. Yuan, S.-H. Huang, Z. Qiao, et. al., " Metasurface-tunable lasing polarizations in microcavity," manuscript under review.

Keywords: Metasurface, Generalized Kerker condition, Lasing polarization, Metalens