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Simulation of Quantum Cascade Lasers

Mohamed, Zakaria LU (2023) FYSK03 20231
Department of Physics
Mathematical Physics
Abstract
This thesis aimed to contribute to the improvement of Quantum Cascade Lasers (QCLs) by focusing on the effective determination of quantum levels in these devices. The current method relies on an outdated Fortran code, which poses challenges when integrating into optimization schemes. To address this issue, the thesis proposed the development of an improved version of the code using Python, thus enhancing readability and flexibility.
Popular Abstract
Lasers, short for "Light Amplification by Stimulated Emission of Radiation," are devices that generate and emit an intense beam of coherent light. The concept of lasers was first proposed in the mid-20th century, and since then have revolutionized numerous industries within scientific research, manufacturing, telecommunications, etc. thus becoming an integral part of our modern lives.

Quantum Cascade Lasers (QCLs) represent a paradigm shift in laser technology, capitalizing on the principles of quantum mechanics. These lasers operate in the mid-infrared to terahertz frequency range, spanning wavelengths from approximately 3 to 300 micrometers. This spectral range, often referred to as the "molecular fingerprint region," is crucial for... (More)
Lasers, short for "Light Amplification by Stimulated Emission of Radiation," are devices that generate and emit an intense beam of coherent light. The concept of lasers was first proposed in the mid-20th century, and since then have revolutionized numerous industries within scientific research, manufacturing, telecommunications, etc. thus becoming an integral part of our modern lives.

Quantum Cascade Lasers (QCLs) represent a paradigm shift in laser technology, capitalizing on the principles of quantum mechanics. These lasers operate in the mid-infrared to terahertz frequency range, spanning wavelengths from approximately 3 to 300 micrometers. This spectral range, often referred to as the "molecular fingerprint region," is crucial for numerous applications in scientific research, industry, and defense. QCLs enable high-resolution spectroscopic analysis, sensitive gas detection, long-range communication, non-destructive imaging, and scientific investigations, revolutionizing fields such as environmental monitoring, industrial process control, medical diagnostics, free-space communication, security screening, and fundamental scientific research.

Unlike traditional lasers, which rely on energy level transitions within a single material, QCLs exploit an innovative design, known as the quantum well, to generate laser action. A Quantum well is formed by layering different semiconductor materials to create what is called a heterostructure. This heterostructure consists of alternating layers, with each layer acting as a barrier or a well for electrons. The barriers prevent the electrons from freely moving across the structure, confining them within the quantum wells.

The confinement of electrons within the quantum wells is crucial for the operation of QCLs. It creates discrete energy levels or states for the electrons, similar to the energy levels in an atom. When an electric current is applied to a QCL, electrons are injected into the quantum wells. As they move through the structure, electrons at higher energy states dexcite in order to occupy lower energy states, subsequently releasing energy in the form of light. This light directly corresponds to the energy difference between the states. After dexcitation, the electrons at lower states undergo what is known as resonant tunneling. This quantum mechanical effect allows the electrons to transition from one quantum to the other, and QCLs are designed such that the lower energy states of one well coincide with higher energy state in its adjacent well, and so the whole process repeats.

This thesis aims to model this process which holds significant importance in understanding, optimizing, and advancing QCL performance. Simulations and modeling play a pivotal role in the development and understanding of new technologies by allowing researchers to gain insights that are otherwise costly to obtain experimentally. (Less)
Please use this url to cite or link to this publication:
author
Mohamed, Zakaria LU
supervisor
organization
course
FYSK03 20231
year
type
M2 - Bachelor Degree
subject
keywords
Quantum Cascade Lasers, Simulations, Numerical Methods, Computational Models, Heterostructures
language
English
id
9127283
date added to LUP
2023-06-19 15:52:16
date last changed
2023-06-19 15:52:16
@misc{9127283,
  abstract     = {{This thesis aimed to contribute to the improvement of Quantum Cascade Lasers (QCLs) by focusing on the effective determination of quantum levels in these devices. The current method relies on an outdated Fortran code, which poses challenges when integrating into optimization schemes. To address this issue, the thesis proposed the development of an improved version of the code using Python, thus enhancing readability and flexibility.}},
  author       = {{Mohamed, Zakaria}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Simulation of Quantum Cascade Lasers}},
  year         = {{2023}},
}