High-Speed Light-Activated Magneto-Optical Rotator And Applications

Open Access
Author:
Yang, Chia-En
Graduate Program:
Electrical Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
September 10, 2010
Committee Members:
  • Shizhuo Yin, Dissertation Advisor
  • Shizhuo Yin, Committee Chair
  • Mohsen Kavehrad, Committee Chair
  • James Kenneth Breakall, Committee Member
  • Qi Li, Committee Member
  • William Kenneth Jenkins, Committee Member
Keywords:
  • magneto-optical rotator
  • high-speed
  • iron(III) borate (FeBO3)
  • microwave assisted synthesis
  • photoconductive switch
  • high DC bias field
Abstract:
It is the purpose of this dissertation to investigate the design and implementation of a magneto-optical (MO) rotator, which is capable of a response/switching time of &#8804; 1 ns and has an aperture larger than 3 mm in diameter, for use in applications of free space optics. The recent advances of ultrafast (< 100 fs) pulse laser systems generated new applications in many research fields, including Physics, Chemistry, Biology, etc., where an intensity or polarization modulator is usually needed. Also, the recent interests in free-space optical communication also call for a polarization modulator to implement a link that can be encrypted with Quantum Key Distribution (QKD) in a stable way. Both acousto-optical (AO) and electro-optical (EO) modulators are not suitable, despite their mature developments. AO modulators are simply too slow and EO modulators have large dispersion for ultra-short pulses. The thick film MO modulator appears to be the best candidate. This dissertation has two main parts that constitutes the MO modulator. The first part addresses the advancement of high DC field biased Photoconductive Semiconductor Switch (PCSS) that is the key to the fast response and switching times. The second part investigates microwave synthesis of iron(III) borate (FeBO3) single crystal fine particles for use in an optical composite to solve the inherent detrimental birefringence problem. As a demonstration, the MO modulator is setup as a light gate in a model experiment to simulate through cloud ballistic imaging. Finally, conclusions and future works are discussed.