University of Illinois Urbana-Champaign

Non-Hermitian aspects of coherently coupled vertical cavity laser arrays

Gao, Zihe

Content Files
GAO-DISSERTATION-2018.pdf

Permalink

https://hdl.handle.net/2142/101491

Description

Title
Non-Hermitian aspects of coherently coupled vertical cavity laser arrays
Author(s)
Gao, Zihe
Issue Date
2018-06-14
Director of Research (if dissertation) or Advisor (if thesis)
Choquette, Kent D.
Doctoral Committee Chair(s)
Choquette, Kent D.
Committee Member(s)
  • Chew, Weng Cho
  • Goddard, Lynford L.
  • Fang, Kejie
Department of Study
Electrical & Computer Eng
Discipline
Electrical & Computer Engr
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2018-09-27T16:17:25Z
Keyword(s)
  • semiconductor laser
  • laser array
Abstract
Two by one (2 × 1) optically coupled electrically isolated vertical cavity surface emitting laser (VCSEL) arrays have been studied both theoretically and experimentally. Because of the tunable gain/loss profile in the array, the coupled laser system is non-Hermitian in analogy with non-Hermitian quantum mechanics. The experimentally observed optical mode tuning and beam steering are inherently connected to the non-Hermiticity of the system. Theoretical investigation of the mode tuning mechanism is conducted first by coupled mode analysis, and then in a more comprehensive coupled rate equation analysis. The theoretical analysis reveals the unique mode tuning mechanism in coupled VCSEL arrays and is shown to be in excellent agreement with experimental characterization. Experimentally, 2 × 1 optically coupled electrically isolated VCSEL arrays have been designed, fabricated, and characterized. We perform two-dimensional characterizations by varying the two independently controlled injection currents into each array and recording the laser output power, spectra, near-field intensity profile, and far-field intensity profile. Two-dimensional maps of the output optical power, interference visibility, and beam steering angles versus the two injection currents are plotted as concise representations of the mode tuning behavior controlled by the current tuning. Arrays with built-in asymmetry between the two lasers demonstrate that the mode tuning behavior can also be engineered by the degree of asymmetry. The coupling coefficient is extracted from the characterizations. The theoretical and experimental investigations presented in this work reveal the unique mode tuning mechanism in weakly coupled diode laser arrays and will guide the future pursuit of improved functionalities in coupled VCSEL arrays.
Graduation Semester
2018-08
Type of Resource
text
Permalink
http://hdl.handle.net/2142/101491
Copyright and License Information
Copyright 2018 Zihe Gao

Owning Collections

Graduate Dissertations and Theses at Illinois PRIMARY
Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Electrical and Computer Engineering
Dissertations and Theses in Electrical and Computer Engineering