Purdue University Graduate School
Wilkey PhD Thesis v3.pdf (3.37 MB)
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Investigation of PT symmetry breaking and exceptional points in delay-coupled semiconductor lasers

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posted on 2021-08-06, 12:14 authored by Andrew Ryan WilkeyAndrew Ryan Wilkey
This research investigates characteristics of PT (parity-time) symmetry breaking in a system of two optically-coupled, time-delayed semiconductor lasers. A theoretical rate equation model for the lasers’ electric fields is presented and then reduced to a 2x2 Hamiltonian model, which, in the absence of time-delay, is PT-symmetric. The important parameters we control are the temporal separation of the lasers (τ), the frequency detuning (∆ω), and the coupling strength (κ). The detuning is experimentally controlled by varying the lasers’ temperatures, and intensity vs. ∆ωbehavior are examined, specifically how the PT-transition and the period and amplitude of sideband intensity oscillations change withκandτ. Experiments are compared to analytic predictions and numerical results, and all are found to be in good agreement. Eigenvalues, eigenvectors, and exceptional points of the reduced Hamiltonian model are numerically and analytically investigated, specifically how nonzero delay affects existing exceptional points.


Degree Type

  • Doctor of Philosophy


  • Physics and Astronomy

Campus location

  • Indianapolis

Advisor/Supervisor/Committee Chair

Gautam Vemuri

Advisor/Supervisor/Committee co-chair

Yogesh Joglekar

Additional Committee Member 2

Jing Liu

Additional Committee Member 3

Jeff Ou

Additional Committee Member 4

Horia Petrache