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366 results on '"Cao, Tun"'

70. Nonlinear Diatomic Metasurface for Real and Fourier Space Image Encoding

Author

Mao, Ningbin, primary, Deng, Junhong, additional, Zhang, Xuecai, additional, Tang, Yutao, additional, Jin, Mingke, additional, Li, Yang, additional, Liu, Xuan, additional, Li, Kingfai, additional, Cao, Tun, additional, Cheah, Kokwai, additional, Wang, Hong, additional, Ng, Jack, additional, and Li, Guixin, additional

Published
2020
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72. Monolayer Conveyor for Stably Trapping and Transporting Sub‐1 nm Particles

Author

Danesh, Mohammad, primary, Zadeh, Mehdi Jafary, additional, Zhang, Tianhang, additional, Zhang, Xiaohe, additional, Gu, Bing, additional, Lu, Jin‐Sheng, additional, Cao, Tun, additional, Liu, Zhengtong, additional, Wee, Andrew T. S., additional, Qiu, Min, additional, Bao, Qiaoliang, additional, Maier, Stefan, additional, and Qiu, Cheng‐Wei, additional

Published
2020
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88. A tunable ultrasensitive plasmonic biosensor based on α-MoO3/graphene hybrid architecture.

Author

Wei, Chenwei and Cao, Tun

Subjects
*BIOSENSORS, *OPTICAL losses, *OPTICAL devices, *OPTICAL properties, *MOLYBDENUM
Abstract

Two-dimensional (2D) materials attract wide attention due to their unique exciting physical properties, which offer new opportunities to design novel devices with enhanced or multiple functionalities. In particular, α-phase molybdenum trioxide (α-MoO3) is an emerging 2D material and exhibits strong anisotropic optical properties and low optical losses in the visible region, making it a promising candidate in tunable optical devices. Here, we proposed a tunable plasmonic biosensor based on α-MoO3/graphene hybrid architectures. By optimizing Au film thickness, the number of α-MoO3 layers and rotation angle, our proposed biosensor can achieve a high phase detection sensitivity of 1.5172 × 105 deg RIU−1 with a biosensor configuration of SF11 prism/47 nm Au/6-layer α-MoO3/monolayer graphene at the rotation angle ϕ = 60°. In addition, the proposed biosensor represents tunable phase detection sensitivity since α-MoO3 can act as a polarizer. Our approach offers a new direction in the development of tunable ultrasensitive plasmonic biosensors for label-free detection and ultralow-concentration analytes. [ABSTRACT FROM AUTHOR]

Published
2021
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89. Surface wave direction control on curved surfaces.

Author

Wei, Chenwei, Cen, Mengjia, Chui, Hsiang-Chen, and Cao, Tun

Subjects
CURVED surfaces, ELECTROMAGNETIC wave propagation, TRANSFORMATION optics, REFRACTIVE index, THEORY of wave motion
Abstract

Transformation optics (TO) has been recognized as an established scheme that can precisely manipulate electromagnetic surface wave propagations. Utilising the advantages of the TO technique, we proposed a TO device which can control the propagation direction of surface waves. The device is based on a generalized Eaton lens and can be realized on curved surfaces. Such a device can be composed of stacked ring layers, where the refractive index of each ring segment can be individually engineered. By engineering the refractive index, the stacked ring structure can guide the propagation direction of the surface wave. It may open a new door to manipulate surface wave propagation on demand. [ABSTRACT FROM AUTHOR]

Published
2021
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90. Largely lowered transition temperature of a VO2/carbon hybrid phase change material with high thermal emissivity switching ability and near infrared regulations

Author

Wang, Shancheng, Liu, Guowei, Hu, Peng, Zhou, Yang, Ke, Yujie, Li, Chuanchang, Chen, Jian, Cao, Tun, Long, Yi, School of Materials Science & Engineering, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore-HUJ Alliance for Research and Enterprise (SHARE), and Nanomaterials for Energy and Energy-Water Nexus (NEW)

Subjects
Camouflage, Materials [Engineering], Hybrid Materials
Abstract

Vanadium oxide (VO2) as a phase changing material possesses abrupt infrared (IR) transmission and thermal emissivity changing during the metal–insulator transition across transition temperature (τc) of 68 °C. However, the high τc, moderate IR transmission and emissivity regulating ability limits its applications in various fields. A VO2/carbon hybrid phase change material fabricated via homemade plasma enhanced chemical vapor deposition is reported. The material shows a best reported thermal emissivity contrast (0.44) among the experimental values, a largely lowered τc (45 °C), promising a near IR-regulation ability with enhanced photothermal effect in smart windows applications. The theoretical calculation results proved that the improvement of emissivity contrast is due to the hybridization of carbon. This work provides a new approach to synthesize VO2 hybrid materials, which have wide applications in camouflage, sensing, and smart windows. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Published
2018

94. Numerical study of biosensor based on α-MoO3/Au hyperbolic metamaterial at visible frequencies.

Author

Wei, Chenwei, Cen, Mengjia, Chui, Hsiang-Chen, and Cao, Tun

Subjects
BIOSENSORS, METAMATERIALS, OPTICAL devices, REFRACTIVE index, OPTICAL limiting, OPTICAL properties, PLASMONICS
Abstract

Hyperbolic metamaterials (HMMs) attract increasing attentions due to their unique optical properties and offer new approaches for realizing novel functionalities in emerging photonic meta-devices. Tunable is one of the most attractive optical properties since multifunction optical devices are one of the important research directions. So far, most active HMMs working in the visible region are based on the combination of metal and phase-change chalcogenides and the performance is limited by the optical losses of phase-change chalcogenides and interdiffusion of the metals with phase-change chalcogenides. In this work, incorporating α-phase molybdenum trioxide (α-MoO3) and Au, an active and low loss HMM device is proposed in the visible region and can effectively overcome the shortcoming. A tunable plasmonic biosensor based on prism coupled α-MoO3/Au HMM is further designed by enhancing Goos–Hänchen (GH) shift, since GH shift is highly sensitive to the refractive index of the substrate. The calculated refractive index sensitivity of this proposed biosensor is of the order of 106 nm/refractive index unit. The proposed approach offers new direction for potential application in the development of the active ultrasensitive biosensor operating at visible range. [ABSTRACT FROM AUTHOR]

Published
2021
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95. Polarization Reflector/Color Filter at Visible Frequencies via Anisotropic α‐MoO3.

Author

Wei, Chenwei, Abedini Dereshgi, Sina, Song, Xianglian, Murthy, Akshay, Dravid, Vinayak P., Cao, Tun, and Aydin, Koray

Subjects
LIGHT filters, OPTICAL materials, ANISOTROPIC crystals, OPTICAL properties, REFRACTIVE index, OPTICAL reflectors
Abstract

2D van der Waals materials have attracted increasing attention in recent years due to their exciting physical properties and offer new opportunities for creating devices with enhanced or novel functionalities. In particular, α‐MoO3 is an emerging member of the fast‐growing 2D family with strong natural anisotropic optical properties. However, anisotropic optical properties of ‐MoO3 in the visible frequency range remain elusive. Here, α‐MoO3 is investigated as an optical material at the visible frequency (450–750 nm), which exhibits a polarization‐dependent complex refractive index due to the anisotropic crystal structure. As a proof of concept, polarization‐sensitive photonic devices including polarization reflectors and polarization color filters are designed and realized by constructing metal–insulator–metal Fabry–Perot cavities. It is observed that resonance frequencies for designed transmission and reflection filters change up to 25 nm with incident polarization which stems from the polarization‐dependent complex refractive indices of α‐MoO3. The largest contrasts are observed for two orthogonal polarization states parallel to the two orthogonal in‐plane crystal directions. The approach in this study offers new directions for potential applications in the development of polarization‐dependent devices based on 2D van der Waals materials for visible frequencies. [ABSTRACT FROM AUTHOR]

Published
2020
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99. Tuneable Thermal Emission Using Chalcogenide Metasurface

Author

Cao, Tun, primary, Zhang, Xinyu, additional, Dong, Weiling, additional, Lu, Li, additional, Zhou, Xilin, additional, Zhuang, Xin, additional, Deng, Junhong, additional, Cheng, Xing, additional, Li, Guixin, additional, and Simpson, Robert E., additional

Published
2018
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