Show simple item record

dc.contributor.authorIsenor, Glenn David.en_US
dc.date.accessioned2014-10-21T12:35:19Z
dc.date.available2001
dc.date.issued2001en_US
dc.identifier.otherAAINQ63477en_US
dc.identifier.urihttp://hdl.handle.net/10222/55745
dc.descriptionThe objective of this thesis was to develop a novel methodology capable of modeling, optimizing, and analyzing the steady-state characteristics of a distributed feedback laser operating in a region above its threshold injection current. Considerations that include the existence of non-linear behaviors such as gain margin reduction at higher injection currents, wavelength stability with changes in injection current, and maximizing the flatness of light energy along the laser's cavity provided the general motivation for this work.en_US
dc.descriptionThis new approach involved integration of the transfer matrix with global optimization strategies to address the numerical challenges associated with modeling the behavioral characteristics of a distributed feedback laser operating in the non-linear above-threshold region. The standard practice has been to first design for a desired steady-state characteristic at the threshold injection current, then to conduct an above-threshold validation to ensure that the characteristic remains. The principle advantage of this new methodology is that it offers the potential of allowing one to directly design for, and model a desired characteristic at the injection current of interest. This capability and the general nature of the methodology offer the potential to form the basis of a flexible and robust laser design tool.en_US
dc.descriptionA success validation of the methodology's basic principles was carried out using a quarter-wave shifted, distributed coupling coefficient, index-coupled, distributed feedback laser. The problem was formulated in terms of an objective function whose value considered both the boundary condition error of the laser's internal light field solution, and the "flatness" of the internal light field. Global optimization was then used to iteratively select optimized values of sectional coupling coefficient and/or inter-sectional phase shift structural parameters so that the laser's internal light field approached a state of maximum flatness within the given problem's parameter constraints. Throughout the range of injection currents considered, optimized light field flatness values were more than 90% reduced over the light field flatness value of an un-optimized reference quarter-wave shifted distributed feedback laser. This was a successful result, verifying the effectiveness of the methodology and opening the way for other types of above-threshold design optimizations. Further analysis of the data revealed evidence that multiple near-optimal light field flatness solutions existed over the range of injection currents evaluated. This was a new and unexpected result.en_US
dc.descriptionIn summary, the original contribution of this work consisted of the development and validation of a new methodology to solve and optimize the steady-state characteristics of a distributed feedback laser structure at the injection current of interest. The fundamental difference in this new methodology over the classical approach is that it is not limited to threshold design considerations. Finally, the evidence of multiple near-optimal solutions observed during the validation process is a new result and is also considered an original contribution.en_US
dc.descriptionThesis (Ph.D.)--Dalhousie University (Canada), 2001.en_US
dc.languageengen_US
dc.publisherDalhousie Universityen_US
dc.publisheren_US
dc.subjectEngineering, Electronics and Electrical.en_US
dc.titleA novel approach to the reduction of a distributed feedback laser's intensity profile non-uniformity using global optimization.en_US
dc.typetexten_US
dc.contributor.degreePh.D.en_US
 Find Full text

Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record