• Abhishek Kumar Srivastava

     

    Prof.

    Hong Kong University of Science and Technology

     

     

    主題

     

    High Speed Ferroelectric Liquid Crystals for High Pixel Density Displays and Photonics

     

    講師簡介

     

    Education：PhD

    Experience：15 years

    Awards/Honors/Patents/Publications：
    Dr. Abhishek Kumar Srivastava is an Assistant Professor and Associate Director of Centre for Display Research, at the Hong Kong University of Science and Technology. He received his Ph.D. degree in 2009 from the University of Lucknow, India. He is the Editor-in-Chief of Journal of Society for Information Displays. He is a senior member of the Society for Information Display (SID), United States, and a member of IEEE and international liquid crystal society, USA. His current research interests include photo-alignment technology, nanomaterials, and fast liquid crystals for advanced displays and photonic devices. In 2014, he received the ILCS Early-Career Award: The Michi Nakata Prize for his early career efforts in the field of FLCs and photo-alignment. In 2018, he received the best I-zone display prototype of the year award from the SID display week for the FLCD. In the same year, he received the LG Bronze award from the Korean information display society. To date, he has published 212 research papers and holds 40 patents/patent applications.

     

    演講大綱

     

    <br>The ferroelectric liquid crystals offer fringing field-free swift electro-optical response time at relatively smaller voltages. Recently, we have disclosed the electrically suppressed helix ferroelectric liquid crystal (ESHFLCs) mode that shows swift response time at lower driving voltages. A balance between the anchoring energy and elastic energy of the helix enables us to achieve high optical quality and shock stability for the ESHFLCs. The ESHFLC is a binary electro-optical mode, as a result, only pulse width modulation can create grayscale that poses big challenges for the high-resolution displays and photonic components. [1-5] Another FLC electro-optical mode called Deformed helix FLC (DHFLC) that can show an analog grayscale can solve the purpose. The DHFLCs with helix pitch smaller than the optical wavelength provides good optical quality and perfect V-Shape switching (see figure. 1). Fringing field and hysteresis-free, fast switching at low driving voltage make the DHFLCs a potential candidate for high-resolution displays applications. Later, we applied these materials to the display and various photonic elements (see fig. 1). In this talk, I will discuss the electro-optics of the FLCs and their selected applications. [6-9]<br> <br>Figure 1: (a) the Transmittance versus voltage curve for the DHFLC and (b) represents the response time dependence on the voltage, the inset shows the polarization optical microscope image for the DHFLC cell. (c) The photograph showing Dammann grating, (d) high resolution display without any fringe field effect. (e) the switchable FLC lenses. <br>References <br>1. Z. Sun, Z. Yuan, R. Shi, H. S. Kwok, A. K. Srivastava, Liquid Crystals, 1-11, 2020.<br>2. Abhishek Kumar Srivastava, Valerii Vashchenko, Ferroelectric Liquid Crystals and Their Application in Modern Displays and Photonic Devices, Chapter 3 in book: Unconventional Liquid Crystals and Their Applications, 2021.<br>3. Chengbin Kang, Maksym F. Prodanov, Yiyang Gao, Valerii V. Vashchenko Abhishek K. Srivastava, Quantum-rod on-chip LEDs for Display backlights with efficacy of 149 lm/w: a step towards 200 lm/w, Adv. Mat., 2104685, 2021. <br>4. Zhi-Bo Sun, Zheng-Nan Yuan, An Nikita, Hoi-Sing Kwok, Abhishek K. Srivastava, Fast-switchable, high diffraction-efficiency ferroelectric liquid crystal Fibonacci grating, , Optics Express, 29 (9), 13978, 2021.<br>5. A. K Srivastava, V. G Chigrinov, H. S Kwok, J. of Soc. Info. Disp., 23 (6), 253, 2015. <br>6. Q Guo, A. K Srivastava, E. P Pozhidaev, V. G Chigrinov, H. S Kwok, Appl. Phys. Exp., 7 (2), 021701, 2014. <br>7. Y. Zheng-nan, Z. Sun, H. Kwok, and A. K. Srivastava, “Fast LiDAR Systems Based on Ferroelectric Liquid Crystal Dammann Grating,” Liquid Crystals, 1-15, 2021. <br>8. Souptik Mukherjee, Zheng-Nan Yuan, Zhi-Bo Sun, An-Ran Li, Chen-Bing Kang, Hoi-Sing Kwok, Abhishek K. Srivastava, Fast Refocusing Lens Based on Ferroelectric Liquid Crystals, Optics Express, 29 (6), 82582021.<br>9. A. K. Srivastava, E. P. Pozhidaev, V. G. Chigrinov and H-S Kwok, J. of Molecular Liquids, 111054, 2019. <br>