Semiconductor quantum-well nanowire lasers : analysis, modeling, and dynamics

Reyhanian, Parya

Semiconductor quantum-well nanowire lasers : analysis, modeling, and dynamics

Reyhanian, Parya

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Publication Type:: Thesis
Issue Date:: 2024

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Field	Value	Language
dc.contributor.author	Reyhanian, Parya
dc.date.accessioned	2024-12-05T21:53:09Z
dc.date.available	2024-12-05T21:53:09Z
dc.date.issued	2024
dc.identifier.uri	http://hdl.handle.net/10453/182377
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	Semiconductor nanowire lasers represent a promising frontier in optoelectronics, with greater potential when coupled with embedded quantum wells. Their small dimensions enable efficient light confinement and amplification, resulting in reduced threshold currents and the possibility of on-chip integration. Integrating quantum wells within nanowires enables precise control over emission wavelength and spectral characteristics due to the step-like density of states. However, existing theoretical models struggle to incorporate both quantum confinement effects and the nanowire cavity effects, hindering predictions of the nanowire laser behavior. Also, the spontaneous emission coupling factor is often treated as a fitting parameter, limiting nanowire laser optimization. This thesis addresses the challenges in the theoretical analysis of quantum well nanowire lasers. We present a comprehensive laser model with three main components: cavity simulations, dynamics of the optical processes, and laser rate equation analysis. The primary contribution of this thesis revolves around the development of a formalism to describe absorption and emission processes within quantum well nanowires. We start from equations originally intended for bulk semiconductors and we further adapt them for quantum wells. Our modifications not only consider the quantum confinement effect within quantum wells but also encompass the integration of the effect of the nanowire cavity on absorption, gain, and spontaneous emission rates. Furthermore, this thesis derives the equations to calculate the spontaneous emission factor and the Purcell effect for quantum well nanowire lasers. One of the advantages of our model is the absence of curve-fitting to experimental data to determine the spontaneous emission factor. Instead, we employ β and the gain derived from our formulations to solve the laser rate equations. We implement our laser model to simulate a ten In0.2Ga0.8As/GaAs multiple quantum well nanowire laser. Simulation results reveal that spontaneous emission is not a constant parameter and it depends on carrier densities. As more carriers are excited into the conduction band, the spontaneous emission factor increases. After reaching a maximum, it starts to decrease when stimulated emissions take over. We also discuss the effect of the quantum well thickness and the temperature on the spontaneous emission emission factor. In summary, our simulations and theoretical framework comprehensively capture the dynamics of nanowire lasers, shedding light on the complex interplay between absorption, gain, and spontaneous emission rates. This thesis significantly advances our fundamental understanding of MQW-nanowire lasers, offering a novel contribution to the theoretical groundwork necessary to harness their unique properties across a wide array of applications.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/182377/1/thesis.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/cph
dc.rights	© 2024 Parya Reyhanian
dc.title	Semiconductor quantum-well nanowire lasers : analysis, modeling, and dynamics	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Semiconductor nanowire lasers represent a promising frontier in optoelectronics, with greater potential when coupled with embedded quantum wells. Their small dimensions enable efficient light confinement and amplification, resulting in reduced threshold currents and the possibility of on-chip integration. Integrating quantum wells within nanowires enables precise control over emission wavelength and spectral characteristics due to the step-like density of states. However, existing theoretical models struggle to incorporate both quantum confinement effects and the nanowire cavity effects, hindering predictions of the nanowire laser behavior. Also, the spontaneous emission coupling factor is often treated as a fitting parameter, limiting nanowire laser optimization. This thesis addresses the challenges in the theoretical analysis of quantum well nanowire lasers. We present a comprehensive laser model with three main components: cavity simulations, dynamics of the optical processes, and laser rate equation analysis. The primary contribution of this thesis revolves around the development of a formalism to describe absorption and emission processes within quantum well nanowires. We start from equations originally intended for bulk semiconductors and we further adapt them for quantum wells. Our modifications not only consider the quantum confinement effect within quantum wells but also encompass the integration of the effect of the nanowire cavity on absorption, gain, and spontaneous emission rates. Furthermore, this thesis derives the equations to calculate the spontaneous emission factor and the Purcell effect for quantum well nanowire lasers. One of the advantages of our model is the absence of curve-fitting to experimental data to determine the spontaneous emission factor. Instead, we employ β and the gain derived from our formulations to solve the laser rate equations. We implement our laser model to simulate a ten In0.2Ga0.8As/GaAs multiple quantum well nanowire laser. Simulation results reveal that spontaneous emission is not a constant parameter and it depends on carrier densities. As more carriers are excited into the conduction band, the spontaneous emission factor increases. After reaching a maximum, it starts to decrease when stimulated emissions take over. We also discuss the effect of the quantum well thickness and the temperature on the spontaneous emission emission factor. In summary, our simulations and theoretical framework comprehensively capture the dynamics of nanowire lasers, shedding light on the complex interplay between absorption, gain, and spontaneous emission rates. This thesis significantly advances our fundamental understanding of MQW-nanowire lasers, offering a novel contribution to the theoretical groundwork necessary to harness their unique properties across a wide array of applications.

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