Article
Chemistry, Physical
Vinicius T. Alvarenga, Dario A. Bahamon, Nuno M. R. Peres, Christiano J. S. de Matos
Summary: Graphene plasmons have tunability, long propagation lengths and ultracompact wavelengths, but light-plasmon coupling in practical applications is challenging. We propose a method to alleviate this by using a practical substrate, silicon carbide (SiC), which naturally enlarges the graphene polariton wavelength. Through calculations, we show that SiC substrate increases the polariton wavelength by an order of magnitude and also increases the propagation length.
Article
Chemistry, Physical
Hang Jiang, Yuanan Zhao, Hao Ma, Cao Feng, Yi Wu, Weili Zhang, Meiling Chen, Mengxia Wang, Yafei Lian, Zhaoliang Cao, Jianda Shao
Summary: A new design concept for broadband light absorption based on the coupling of epsilon-near-zero (ENZ) and localized surface plasmon resonance (LSPR) modes is proposed. Experimental results show that a single-layer patterned indium tin oxide (ITO) film on a two-dimensional microsphere array can achieve over 98% light absorption in a wide wavelength range. These findings provide a low-cost solution for designing broadband perfect absorbers based on ENZ materials, with potential applications in near-infrared sensors, photoelectric detection, and ENZ photonics.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Physical
Qin Chen, Shichao Song, Huacun Wang, Li Liang, Yajin Dong, Long Wen
Summary: A dual-resonance light coupling scheme is proposed in this work to achieve an almost one order-of-magnitude improvement in modulation depth-bandwidth product. By optimizing the dual-resonance configuration, decent light modulation can be obtained within a large operation wavelength band covering two resonances.
Article
Chemistry, Physical
Yujing Ran, Huiping Lu, Shujun Zhao, Qian Guo, Chang Gao, Zhaotan Jiang, Zhi Wang
Summary: Metal nitride NbNx films with different nitrogen content were prepared and demonstrated stoichiometry-tunable on lattice constant, chemical state, and plasmonic properties. The films exhibit dual ENZ behavior in the range of 400 to 1000 nm, with tunable negative real part of epsilon below 1.0. Non-stoichiometric defects, particularly cation vacancies, were found to be key factors affecting the ENZ behavior of NbNx films.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Viacheslav V. Medvedev
Summary: This study presents a theoretical analysis of total absorption conditions in a Dallenbach absorber structure with a lossy coating layer on a metal substrate. It describes all possible combinations of coating material properties and thicknesses for complete absorption under normal incidence of a plane wave. The design options include both conventional materials with refractive index greater than unity and epsilon-near-zero materials, with simple analytical relations found for the latter. Comparisons of absorption coefficient angular dependences and electromagnetic field distribution profiles are made for coatings with different refractive indices. The design of an indium-tin oxide (ITO) coating on an aluminum substrate is discussed as an example of an ENZ-based Dallenbach absorber.
Article
Chemistry, Physical
Ryan Bower, Matthew P. Wells, Freya Johnson, Rebecca Kilmurray, Brock Doiron, Eleonora Cali, Giuseppe Mallia, Bin Zou, Andrei P. Mihai, Nicholas M. Harrison, Sarah Fearn, Rupert Oulton, Neil McN. Alford, Lesley F. Cohen, Peter K. Petrov
Summary: This study investigates the optical response and electrical properties of reactively sputtered niobium oxynitride thin films through experimental and computational simulations. The experimental results show that these films have screened plasma wavelengths tunable over a range of 90 nm, and exhibit a double epsilon-near-zero behavior. This behavior is attributed to the incorporation of oxygen into the films during deposition.
APPLIED SURFACE SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
Chenxingyu Huang, Siwei Peng, Xuanyi Liu, Jiaye Wu, Hongyan Fu, Lei Lu, Shengdong Zhang, Qian Li
Summary: Epsilon-near-zero (ENZ) indium tin oxide (ITO) nanofilms were fabricated by magnetron sputtering, and their ENZ properties were controlled through factors in the sputtering process such as gas ratio and annealing. The ENZ wavelength was blue-shifted by 609 nm and intrinsic loss was reduced by 63.2% after annealing, resulting in improved linear scattering properties and stronger field intensity enhancement. The proposed sputtering protocol offers a feasible technique to control the linear and nonlinear ENZ performance.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Kyu-Ri Choi, Minjae Kim, Jeong Weon Wu, Anthony D'Aleo, Yeon Ui Lee
Summary: Researchers have achieved enhanced directionality of photoluminescence emission by placing an organic dielectric film on top of a polymeric fluorophore film. The directive emission is increased by 42% by utilizing the structural coherence in the polymeric fluorophore film and the epsilon-near-zero response in the organic dielectric film. This capability to control directive emission with organic dielectric films is highly useful in applications requiring bio-compatibility of a fluorophore-embedding medium.
Article
Nanoscience & Nanotechnology
Qi Xiao, Calum Kinnear, Timothy U. Connell, Muhammad Kalim Kashif, Christopher D. Easton, Aaron Seeber, Laure Bourgeois, Gus O. Bonin, Noel W. Duffy, Anthony S. R. Chesman, Daniel E. Gomez
Summary: The study demonstrates a reliable method for preparing alloyed nanoparticles without the need for colloidal synthesis or time-consuming lithography. The alloyed AuPd nanoparticles can be used to enhance the efficiency of electromagnetic perfect absorbers and exhibit high photon-to-energy efficiencies.
ACS APPLIED NANO MATERIALS
(2021)
Article
Optics
Seung Won Jun, Jong Hyuk Yim, Ji-Yong Park, Soonil Lee, Yeong Hwan Ahn
Summary: Thermal reduction of graphene oxide films achieves terahertz epsilon-near-zero (ENZ) material, which exhibits extraordinary light manipulation capabilities for applications such as superabsorption, hyper-resolution imaging, and ultrasensitive sensing. The ENZ films can be transferred to curved surfaces and hybridized with metamaterial patterns, enabling enhanced performance in detecting low index materials.
LASER & PHOTONICS REVIEWS
(2023)
Article
Nanoscience & Nanotechnology
Sisira Suresh, Orad Reshef, M. Zahirul Alam, Jeremy Upham, Mohammad Karimi, Robert W. Boyd
Summary: This study demonstrates the strong nonlinear optical properties of an optical ENZ metamaterial, showing that the nonlinear enhancement is proportional to the linear effective refractive index. In contrast to homogeneous ENZ materials, these metamaterials offer greater tunability and can be designed with large nonlinearities at any specified optical wavelength within the visible spectrum.
Article
Chemistry, Multidisciplinary
Soham Saha, Mustafa Goksu Ozlu, Sarah N. Chowdhury, Benjamin T. Diroll, Richard D. Schaller, Alexander Kildishev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: The unique properties of emerging photonic materials, conducting nitrides and oxides, are explored in this study. The optical properties of polycrystalline titanium nitride and aluminum-doped zinc oxide can be controlled by tailoring the film thickness. The study demonstrates their potential for ENZ-enhanced photonic applications, including optical circuitry, tunable metasurfaces, and nonlinear optical devices.
ADVANCED MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Aleksei Anopchenko, Sudip Gurung, Subhajit Bej, Ho Wai Howard Lee
Summary: Using electrodynamical description, an expression for the electric-field intensity enhancement (FIE) due to epsilon-near-zero (ENZ) polariton modes is presented. The study shows that FIE reaches a limit in ultrathin ENZ films, inversely proportional to ENZ losses. The research also predicts high values of FIE in ultrathin polar semiconductor films.
Article
Optics
Ya-Ting Bai, Hai-Yan Zheng, Qiang Zhang, Shao-Ding Liu
Summary: This study proposes a design method for double nanoparticle arrays and demonstrates the effective excitation of sharp magnetic lattice resonances by adjusting the relative positions of the nanoparticles, leading to narrowband perfect absorption. The flexible tunability and realization of narrowband perfect absorption make this design suitable for both linear and nonlinear nanophotonic devices.
OPTICS AND LASER TECHNOLOGY
(2022)
Article
Thermodynamics
Yunxia Ma, Fei Liu, Honggang Pan, Hongjian Zhang, Shuxia Yan, Ailing Zhang
Summary: This paper proposes a dynamically tunable and switchable perfect infrared absorber that exhibits excellent electrical regulation performance and high absorptance. The absorption mechanism is explained using a multiple interference model, and it is proven to be polarization insensitive.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2024)
Article
Optics
Khant Minn, Blake Birmingham, Brian Ko, Ho Wai Howard Lee, Zhenrong Zhang
Summary: This study presents a method for fabricating needle-shaped plasmonic nanoantennas using electron-beam-induced evaporation of platinum and demonstrates the coupling of light from the fiber waveguide to the nanoantenna plasmonic mode. The research is a significant step towards the widespread application of optical fibers in nearfield spectroscopic techniques.
PHOTONICS RESEARCH
(2021)
Article
Optics
Qiu-Hua Wang, Pei-Nan Ni, Yi-Yang Xie, Qiang Kan, Pei-Pei Chen, Pan Fu, Jun Deng, Tai-Lai Jin, Hong-Da Chen, Ho Wai Howard Lee, Chen Xu, Patrice Genevet
Summary: Metasurfaces offer precise control over optical wavefronts on a subwavelength scale, enabling the development of compact and multifunctional optoelectronic systems. The integration of metasurfaces with vertical cavity surface-emitting lasers (VCSELs) allows for the generation of structured light at a wafer level, showcasing the potential for compact and scalable structured light systems. The experimental demonstration of ultracompact beam structured laser chips with versatile functionalities highlights the potential applications in various fields such as 3D imaging, displays, robotic vision, and augmented/virtual reality.
LASER & PHOTONICS REVIEWS
(2021)
Article
Chemistry, Multidisciplinary
Khant Minn, Aleksei Anopchenko, Ching-Wen Chang, Ragini Mishra, Jinmin Kim, Zhenrong Zhang, Yu-Jung Lu, Shangjr Gwo, Ho Wai Howard Lee
Summary: Room-temperature photoluminescence enhancement of molybdenum disulfide monolayers on epitaxial titanium nitride thin films is observed, with stronger enhancement as titanium nitride becomes more metallic, especially at excitation wavelengths equal to or longer than the titanium nitride's epsilon-near-zero (ENZ) wavelength. The enhancement is attributed to increased excitation field in molybdenum disulfide at titanium nitride's ENZ wavelength and interference effects for thick spacers that separate molybdenum disulfide flakes from titanium nitride films in the metallic regime.
Article
Nanoscience & Nanotechnology
Meng-Ju Yu, Chih-Li Chang, Hao-Yu Lan, Zong-Yi Chiao, Yu-Chia Chen, Ho Wai Howard Lee, Yia-Chung Chang, Shu-Wei Chang, Takuo Tanaka, Vincent Tung, Ho-Hsiu Chou, Yu-Jung Lu
Summary: Research has shown that a titanium nitride metasurface absorber demonstrates broadband absorption with over 92% average absorption in the wavelength range of 400 to 750 nm, attributed to localized surface plasmon resonance. By integrating this technology with a polymer photocatalyst, a 300% increase in hydrogen evolution rate was observed due to enhanced rates of light absorption, carrier separation, and hot-carrier transfer, providing a new approach for high-efficiency solar energy harvesting systems.
Review
Physics, Multidisciplinary
Jingyi Yang, Sudip Gurung, Subhajit Bej, Peinan Ni, Ho Wai Howard Lee
Summary: Optical metasurfaces with subwavelength thickness have the ability to control the phase, amplitude, and polarization of light, making them promising for fundamental optics and optical applications. Introducing active functionalities to these metasurfaces is essential for the development of next-generation flat optical components and devices. Attempts have been made to develop tunable optical metasurfaces with dynamic control of optical properties and early-stage device functions using novel active materials and tunable mechanisms. Although these active metasurfaces show promise for practical applications, significant challenges remain. This review provides a comprehensive overview of recently-reported tunable metasurfaces and compares their capabilities and limitations for various photonic applications.
REPORTS ON PROGRESS IN PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Zong-Yi Chiao, Yu-Chia Chen, Jia-Wern Chen, Yu-Cheng Chu, Jing-Wei Yang, Tzu-Yu Peng, Wei-Ren Syong, Ho Wai Howard Lee, Shi-Wei Chu, Yu-Jung Lu
Summary: Refractory hafnium nitride (HfN) plasmonic crystals capable of generating high-resolution full-visible color have been reported. The unique features of HfN, such as its high bulk plasmon frequency, enable localized surface plasmon resonance in the visible range, allowing for colors ranging from blue to red.
Article
Multidisciplinary Sciences
Ming Lun Tseng, Michael Semmlinger, Ming Zhang, Catherine Arndt, Tzu-Ting Huang, Jian Yang, Hsin Yu Kuo, Vin-Cent Su, Mu Ku Chen, Cheng Hung Chu, Benjamin Cerjan, Din Ping Tsai, Peter Nordlander, Naomi J. Halas
Summary: A metalens that can generate and focus VUV light simultaneously has been successfully created by the research team. The metalens is ultracompact and phase-matching free, making it a useful tool for developing low-loss VUV components and increasing the accessibility of VUV light.
Article
Optics
Aysan Bahari, Kyle Sower, Kai Wang, Zehua Han, James Florence, Yingying Wang, Shoufei Gao, Ho Wai Howard Lee, Marlan Scully, Aleksei Zheltikov, Alexei Sokolov
Summary: In this study, we investigated the application of coherent anti-Stokes Raman spectroscopy in revolver fiber. We found that revolver fiber can significantly enhance the vibrational coherent anti-Stokes Raman signal of nitrogen and produce a signal with near-zero non-resonant background.
Article
Optics
Jingyi Yang, Khant Minn, Aleksei Anopchenko, Sudip Gurung, Ho Wai Howard Lee
Summary: This article reports on the experimental excitation of a highly confined epsilon-near-zero (ENZ) mode in a side-polished optical fiber coated with a deep subwavelength thick layer of aluminum-doped zinc oxide (AZO). The uniform AZO layer is fabricated on the fiber using atomic layer deposition, with optimized permittivity at the near-infrared wavelength. The ENZ-coated fiber exhibits highly polarization- and wavelength-dependent transmission with strong resonance strength and a relatively long propagation/light-matter interaction length.
LASER & PHOTONICS REVIEWS
(2023)
Article
Nanoscience & Nanotechnology
Aleksei Anopchenko, Sudip Gurung, Subhajit Bej, Ho Wai Howard Lee
Summary: Using electrodynamical description, an expression for the electric-field intensity enhancement (FIE) due to epsilon-near-zero (ENZ) polariton modes is presented. The study shows that FIE reaches a limit in ultrathin ENZ films, inversely proportional to ENZ losses. The research also predicts high values of FIE in ultrathin polar semiconductor films.
Article
Chemistry, Physical
Ching-Wen Chang, Chiao-Tzu Huang, Jhih-Sheng Wu, Zih-Hao Song, Chih-Hsuan Liao, Quynh T. Dang, Yu-Jung Lu, Ho Wai Howard Lee, Hyeyoung Ahn, Shangjr Gwo
Summary: In this study, ultrathin and scalable TiN epitaxial structures were demonstrated for tunable infrared plasmonics. By controlling the thickness and grating structure parameters of the epitaxial films, frequency-tunable plasmonic metasurfaces were achieved. These materials hold great potential for infrared plasmonic applications such as thermal photovoltaics, photodetectors, and biosensors.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Materials Science, Multidisciplinary
David Dang, Aleksei Anopchenko, Sudip Gurung, Zoey Liu, Xuguo Zhou, Ho Wai Howard Lee
Summary: By constructing multilayer ENZ thin films, broadband ENZ properties and perfect absorption can be achieved. This work utilizes a residual generative neural network to optimize the broadband and perfect absorption properties of ultrathin ENZ materials, resulting in multi-stack ENZ layers with a maximum absorption above 99% over a bandwidth hundreds of nanometers wide.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Nanoscience & Nanotechnology
Indra Ghimire, Jingyi Yang, Sudip Gurung, Satyendra K. Mishra, Ho Wai Howard Lee
Summary: This study presents a polarization-dependent optical filter fabricated by nanopatterning an asymmetric metallic metasurface array on the end-facet of a polarization-maintaining photonic-crystal fiber. The experimental results demonstrate highly polarization- and wavelength-dependent transmission in the telecommunication wavelength range, with a transmission efficiency of about 70%. Full-wave electromagnetic simulations agree well with the experimental results. These advanced meta-structured optical fibers have the potential to be used as novel ultracompact in-fiber filters, splitters, and polarization converters.
