Reseaech Highlights
Dear guests,
Welcome to my personal page where I share our recent studies and a range of fascinating physical concepts in the field of nanophotonics. We strive to unravel the mysteries of wave-physical phenomena and ultimately propose useful optical/photonic applications based on the newly acquired knowledge.
Our motto is to anchor the phenomenon of drifting with a persistent thought. Recently, our research has focused on the following topics based on crucial physical notions such as symmetry, topology, and quantum-optical analogy in nanophotonics systems.
Novel metaphotonic structures to demonstrate hypothetical predictions
Additional degrees of freedom and principles for manipulating photon in a new way
Flat optical devices and structured light for compact, lightweight, and new functional photonic applications such as AR/VR, LiDAR, and holograms
Global appearance of unidirectional radiation
The unidirectionality of leakage radiation is an extreme effect of light-matter interactions in metasurfaces, crucial for enhancing the efficiency and performance of various photonic devices such as couplers and antennas. So far, this effect has been known to be feasible only under specific frequency-wavevector condition at the local point on a dispersion band because previous approaches fundamentally rely on an accidental interference configuration. Here, we experimentally realize global appearance of predominant single-sided radiation using a glide symmetric bilayer metasurface, not limited to a local point, but existing continuously across nearly the entire dispersion bands.
(In preparation, 2024)
(In preparation, 2024)
Observation of Dirac domain-wall in optical metasurfaces
The Jackiw-Rebbi soliton, a zero-energy solution in the domain-wall of Dirac equation, is of significant importance in topological physics as a fundamental description for boundary states. Despite being implemented across various platforms from electronic to photonic systems, the Jackiw-Rebbi states under the non-Hermitian characteristics of metasurfaces, which induce a strong out-of-plane interaction, remain largely unexplored. Here, we report clear experimental results for a fruitful connection between Dirac physics and optical metasurfaces.
(In preparation, 2023)
(In preparation, 2023)
Dirac bilayer metasurfaces as an inverse Gires-Tournois etalon
Pure transmission phase modulation is a highly desired means for the efficient implementation of compact optical phased-array elements such as a metalens and LiDAR. To date, such functionality has been shown to be limited at reflection-type operation (Gires-Tournois etalon) or certain local points of dispersion bands. Here, we show global manifestation of the pure-phase modulation in transmission along the entire Dirac band in bilayer metasurfaces.
(Submitted, 2023)
(Submitted, 2023)
Topological beaming of light
Nanophotonic light emitters are key components in numerous application areas because of their compactness and versatility. Here, we propose an unprecedented beaming mechanism of leaky Jackiw-Rebbi state bound to the interface of a topological junction metasurface that takes advantage of submicrometer footprint size, small divergence angle,high efficiency, and adaptable beamshaping capability. This effect may trigger the realization of a new class of nanophotonic antennas and offer a practical guidance for designing topological resonances in flat optical systems.
(Science Advances, 2022)
Synthetic photonic topological nodal phase
The notion of synthetic dimensions in artificial photonic systems has received considerable attention as it provides novel methods for exploring hypothetical topological phenomena as well as potential device applications. We present nanophotonic manifestation of a 2D topological nodal phase in bilayer gratings by an analogy between a topological semimetal and glide symmetric photonic lattices
(Physical Review Letters, 2022)
Topological guided-mode resonances
We show that robust guided-mode-resonance states exist in metasurface domain-wall structures. Using the non-Hermitian photonic analogy of the Dirac equation, we derive essential conditions for photonic Jackiw-Rebbi-state resonances taking advantage of unique spatial confinement and spot-like spectral features which are remarkably robust against random parametric errors.
(Nanophotonics, 2021)
PN junction metasurfaces for efficient spatial light modulators
We propose a free-space electro-optic transmission modulator based on multiple p-n-junction semiconductor subwavelength gratings. The proposed device operates with a high-Q guided-mode resonance undergoing electro-optic resonance shift due to direct electrical control. Using rigorous electrical and optical modeling methods, we theoretically demonstrate a modulation depth of 84%, on-state efficiency 85%, and on-off extinction ratio of 19 dB at 1,550 nm wavelength under electrical control signals within a favorably low bias voltage range from −4 V to +1 V.
(Scientific Reports, 2017)
(Scientific Reports, 2017)
LioT: News & Views
A new journey
I am thrilled to announce that starting March 2024, I will be embarking on a new postdoctoral journey at the Center for Integrated Nanotechnologies (CINT) at Sandia National Laboratories, located in Albuquerque, USA. Joining this remarkable team feels like a dream come true, and I'm profoundly grateful to my former colleagues, mentors, and family who have shaped my ambitions and guided my professional growth.
I also want to express my heartfelt thanks to my new colleagues at CINT for their warm welcome and for assisting with my family's relocation. I'm filled with energy and optimism about what we'll achieve together in our quest to advance topological physics, metasurface technologies, and nanophotonics. I'm eagerly looking forward to this exciting journey.
Mar. 2024