Investigation of PT Symmetry Breaking and Exceptional Points in Delay-Coupled Semiconductor Lasers
Abstract
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. ∆ω behavior are examined, specifically how the PT-transition and the period and amplitude of sideband intensity oscillations change with κ and τ . 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
Ph.D.
Advisors
Joglekar, Purdue University.
Subject Area
Mathematics|Optics
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