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CHEAH, Kok Wai

CHEAH, Kok Wai, 謝國偉教授

Dr. Elizabeth K. S. Law Endowed Professor in Advanced Materials
Chair Professor in Department of Physics
Director, Institute of Advanced Materials

B.Sc. Hons, ARCS, M.Sc., DIC, Ph.D., CSci, CPhys. FinstP
Imperial College London

Senior Visiting Professor of Fudan University, Shanghai, China
Adjunct Professor of Sun Yat-sen University, Guangzhou, China
Visiting Professor of Jinan University, Guangzhou, China

Current Research Interests

  1. Optical Properties of Plasmonic Devices Coupling of SPP and F-B Cavity Modes 
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Figure 1.1
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Figure 1.2
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Figure 1.3
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Figure 1.4

Giant nonlinear optical activity of achiral origin in planar metasurfaces with quadratic and cubic nonlinearities
We show that the overwhelming contribution to this nonlinear circular dichroism (CD) is of achiral origin. Therefore, our work sheds new light on the origin of the nonlinear CD effect in achiral planar materials. Our study also opens up new routes for designing chip- type bio-sensing platforms, which may allow for highly sensitive detection of bio- and chemical molecules with weak chiroptical response.

 
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Figure 1.5 Schematic of nonlinear optical dichroism from Trisceli- and Gammadion-type plasmonic nanostructures with three-(C3) and four-fold(C4) rotational symmetries.
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Figure 1.6 Geometry parameters and transmission properties of the plasmonic nanostructures.
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Figure 1.7 SHG-CD and THG-CD from the Trisceli- and Gammadion- type plasmonic nanostructures.

 

2. Highly Efficient Green Organic Light-Emitting Devices Based On Intermolecular Exciplex
 

MEMD2015
Figure 2

3. Transparent OLED
Transparent OLED is developed in IAM of Hong Kong Baptist University. The aim is to develop a new class of transparent cathode that requires no/minimum modification to the OLED device structure. Therefore it can directly replace existing metal cathode with minimum/no change to the OLED emission characteristics. We have achieved more than 35% (45%-25%) average transmission in optical range for the cathode and used a standard OLED structure to demonstrate its performance.

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Figure 3.1
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Figure 3.2

Selected Publications

  1. Fatemeh Hosseini Alast, Guixin Li, and Kok Wai Cheah `Rabi-like splitting from large area plasmonic microcavity ', AIP ADVANCES, 7, 085201(2017).
  2. Shumei Chen, Yuan Cai, Guixin Li, Shuang Zhang, and Kok Wai Cheah `Geometric metasurface fork gratings for vortex-beam generation and manipulation ', Laser Photonics, 1-5 (2016).
  3. Yiren Xia, O. Yin Wan, and Kok Wai Cheah `OLED for human centric lighting ', Optical Materials Express, 1905-1913 (2016).
  4. Shumei Chen, Franziska Zeuner, Martin Weismann, Bernhard Reineke, Guixin Li, Ventsislav Kolev Valev, Kok Wai Cheah, Nicolae Coriolan Panoiu, Thomas Zentgraf, Shuang Zhang, `Giant nonlinear optical activity of achiral origin in planar metasurfaces with quadratic and cubic nonlinearities ', Advanced Materials, 28, 2992-2999 (2016).
  5. Jinfeng Zhang, Wencheng Chen, Sergii Kalytchuk, King Fai Li, Rui Chen, Chilhaya Adachi, Zhan Chen, Andrey L. Rogach, Guangyu Zhu, Peter K. N. Yu, Wenjun Zhang, Kok Wai Cheah, Xiaohong Zhang, and Chun-Sing Lee, `Self-Assembly of Electron Donor-Acceptor-Based Carbazole Derivatives: Novel Fluorescent Organic Nanoprobes for Both One- and Two-photon Cellular Imaging ', ACS Appl. Mater. Interfaces, 8(18), pp 11355-11365 (2016).
  6. Lei Guo, King Fai Li, Xiaoqin Zhang, Kok Wai Cheah and Man Shing Wong, `Highly Efficient Multiphoton-Pumped Frequency-Upconversion Stimulated Blue Emission with Ultralow Threshold from Highly Extended Ladder-Type Oligo (p-phenylene)s',', Angew. Chem. Int. Ed., 55, 10639 (2016).
  7. Guixin Li, Shumei Chen, Nitipat Pholchai, Bernhard Reinehe, Polis Wing Han Wong, Edwin Yue Bun Pun, Kok Wai Cheah, Thomas Zentgraf and Shuang Zhang, `Continuous control of the nonlinearity phase for harmonic generations ', Nature Materials, 14, 607-612 (2015).
  8. K.L.Chan, G. X. Li, and Kok Wai Cheah, `Spatially variant color light source using amplified spontaneous emission from organic thin films ', Optical Materials Express, 5, 497-502 (2015).
  9. Xin Jiang Feng, Shao Fu Chen, Yong Ni, Man Shing Wong, Maggie M.K. Lam, Kok Wai Cheah, Guo Qiao Lai, “Fluorene derivatives for highly efficient non-doped single-layer blue organic light-emitting diodes”, Organic Electronics, 15, 57-64 (2014).
  10. Shumei Chen, Guixin Li, Franziska Zeuner, Wing Han Wong, Edwin Yue Bun Pun, Thomas Zentgraf, Kok Wai Cheah, and Shuang Zhang, “Symmetry-Selective Third- Harmonic Generation from Plasmonic Metactystals”, Physical Review Letters, 113, 033901 (2014).
  11. Wanggui Yang, Pui Shan Chan, Miu Shan Chan, King Fai Li, Pik Kwan Lo, Nai Ki Mak, Kok Wai Cheah, and Man Shing Wong, “Two-photon fluorescence probes for imaging of mitochondria and lysosomes”, Chem. Commun. 49, 3428-3430 (2013).
  12. Lei Guo, King Fai Li, Man Shing Wong and Kok Wai Cheah, “Star-shaped ladder-type ter(p-phenylene)s for efficient multiphoton absorption”, Chem. Commun., 49, 3597-3599(2013).
  13. H. L. Tam, K. W. Cheah, David T. P. Goh and Joseph K. L. Goh, "Iridescence and nano-structure differences in Papilio butterflies", Optical Material Express, 3, 1087-1092 (2013).
  14. Shumei Chen, Guixin Li, Dangyuan Lei and Kok Wai Cheah, “Efficient energy exchange between plasmon and cavity modes via Rabi-analogue splitting in a hybrid plasmonic nanocavity”, Nanoscale, 5(19), 9129-9133 (2013).
  15. Guixin Li, Ming Kang, Shumei Chen, Shuang Zhang, Edwin Yue-Bun Pun, K. W. CHeah, “Spin-Enabled Plasmonic Metasurfaces for Manipulating Orbital Angular Momentum of Light”, Nano Letters, 13, 4148-4151(2013).
  16. Lingling Huang, Xianzhong Chen, Holger Muhlenbern, Hao Zheng, Shumei Chen, Benfeng Bai, Qiaofeng Tan, Guofan Jing, Kok Wai Cheah, Cheng-Wei Qiu, Jensen Li, Thomas Zentgraf and Shuang Zhang, “Three-dimensional optical holography using plasmonic metasurface”, Nature Communications, 4, 1-7(2013).
  17. Shumei Chen, Guixin Li, Winghan Wong, Yuebun Pun and Kokwai Cheah, “Surface plasmon enhanced third harmonic generation from metal-organic hybrid plasmonic”, Adv Optical Mat., 1, 522-526 (2013).
  18. G. X. Li, S. M. Chen, W. H. Wong, E. Y. B. Pun and K. W. Cheah, “Highly flexible near-infrared metamaterials”, Optics Express, 20, 397-402 (2012).