High-Bitrate Photodetection in Ultraviolet-to-Visible for Optical Wireless Communication

  • Chun Hong Kang

Student thesis: Doctoral Thesis

Abstract

Optical wireless communication, taking advantage of the unlicensed ultraviolet-to visible wavelength region of the electromagnetic spectrum, had been coined as the next-generation wireless communication technology and holds promises to deliver a high-speed, reliable, and secured broadband experience. The push towards the optical-based medium is manifested by the demand for additional channel bandwidth to accommodate the rapid growth of the Internet-of-Things (IoT) and Internet-of-Underwater-Things (IoUT). Therefore, high-bitrate optoelectronics devices and components forming the transceiver units used in an optical wireless communication system require substantial progression to accelerate the development of this paradigm-shifting technology. In this dissertation, we demonstrated a plethora of optical detection platforms to circumvent the existing long-standing issues related to modulation bandwidth, wavelength-selectiveness, and solar-blind ultraviolet-C detection found in conventional planar silicon-based optical detectors. Herein, we presented the semipolar group-III-nitride-based micro-photodiodes for enabling up to Gbit/s optical detection in the ultraviolet-to-violet domain. The wavelength-selectiveness nature of the micro-photodiodes enabled a bitrate of up to 1.5 Gbit/s based on a power-saving on-off-keying modulation scheme. While it offers a high bitrate for the optical communication link, it restricts its detection size and angle-of-view due to the conventional resistance-capacitance and ├ętendue limits. Therefore, we also explored using polymer-based scintillating fibers as a high-speed and near-omnidirectional optical detection platform to cater to various dynamic scenarios in optical wireless communication. The detection platform formed by the scintillating fibers enabled near-omnidirectional and large-area optical detection without sacrificing the modulation bandwidth. These investigations paved the way towards relieving the resistance-capacitance limit while addressing the pointing, acquisition, and tracking issue in underwater wireless optical communication. Subsequently, we also presented a novel wavelength-converting mechanism based on halide-perovskite nanocrystals and a conventional silicon-based platform. This demonstration addressed the lack of ultraviolet-C optical detectors in the existing market and enabled future solar-blind optical communication links. Finally, we also presented on halide-perovskite polymer-based scintillating fibers as the high-bitrate and near-omnidirectional optical detection platform. Our studies successfully addressed the existing inadequacy for high-bitrate photodetection. These works could play a significant role in progressing the technology forward, based on bottom-up material and devices innovation, to offer a reliable internet connection to the future highly interconnected society.
Date of AwardNov 2021
Original languageEnglish (US)
Awarding Institution
  • Computer, Electrical and Mathematical Science and Engineering
SupervisorBoon Ooi (Supervisor)

Keywords

  • Photodetectors
  • Optical wireless communication
  • Perovskite
  • Optoelectronics
  • Scintillating fibers

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