Electromagnetic Theory of Distributed Feedback Lasers in Periodic Dielectric Waveguides

Author: Evans, Gary Alan

Year: 1975

Degree: Dissertation (Ph.D.)

Advisor: Papas, Charles Herach

Committee Member: Unknown, Unknown

Option: Electrical Engineering; Physics

DOI: 10.7907/QMW8-1287

Abstract

A theory for distributed feedback lasers in transversely bounded structures is developed. The space harmonics approach is used to discuss the general properties of periodic structures. The coupled mode approach is used to develop expressions for the threshold gain, longitudinal mode structure, and electromagnetic field distribution for distributed feedback lasers.

Three basic structures are considered for distributed feedback lasers--thin film waveguides, diffusion waveguides, and fiber wave-guides.

Equations for the amplification of a waveguide mode that extends transversely over both regions with and without gain are derived.

Analytical expressions are derived for coupling between modes in periodically perturbed dielectric waveguides. Sinusoidal perturbations of the electric permittivity and of the waveguide boundary are considered.

Theoretical results indicate that an optimum design of distributed feedback lasers can be achieved by an appropriate choice of geometrical parameters. Regions of optimum design are illustrated in numerous plots of normalized threshold gain versus normalized laser frequency.

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