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URN etd-0526114-161004
Author Yueh-Chen Li
Author's Email Address i1681603@gmail.com
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Department Physics
Year 2013
Semester 2
Degree Master
Type of Document
Language English
Title Analogy between the Polarization Switching of Vertical-Cavity Surface-Emitting Lasers and Ising Model
Date of Defense 2014-06-03
Page Count 50
Keyword
  • polarization switchingn
  • VCSELs
  • phase transitio
  • Ising model
  • Abstract An Ising simulation is used to investigate the phase transition in the polarization switching (PS) of vertical-cavity surface-emitting lasers (VCESLs). This study focuses on two features of VCSELs’ light. One is the spatial coherence of beam, and the other is the order-to-order transition of VCSELs’ PS (VPS). The main laser represented in this thesis is a single-transverse-mode VCSEL with a Gaussian beam profile. From a point of view of an excellent spatial coherence due to stimulated emission, we added a Gaussian-function distribution in the interaction energy of a 2-D Ising model. The simulation result shows a weak first-order phase transition for disorder-to-order transition because of the inhomogeneous interaction in space, and suggests that it is an improper way to imitate the spatial coherence of laser. For the order-to-order transition in the VPS, the Ising simulation with an external field could give a phenomenological description to understand the interaction in VPS and suggest VPS is a first order phase transition (FOPT). Although the cavity of VCSEL has a great circular symmetry, the results also indicate an existence of a symmetry-breaking mechanism induced by injection current in VPS system and imply the interaction for an abrupt VPS with hysteresis should be strong enough to make the whole system be in a spontaneous order state. The reference value of the interaction strength is 1/2.3 for the Ising model. This study proposes a possible answer to VPS’s interaction. We hope more experiments for the abrupt and the gradual VPS could support it.
    Advisory Committee
  • Der-Jun Jang - chair
  • Wei-Feng Tsai - co-chair
  • Yi-Jen Chiu - co-chair
  • Wang-Chuang Kuo - co-chair
  • Tsu-Chiang Yen - advisor
  • Files
  • etd-0526114-161004.pdf
  • indicate access worldwide
    Date of Submission 2014-07-04

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