Modeling of quantum cascade lasers

• Main Author: Shen, Xi Wei
• Other Authors: Wang Qijie
• Format: Thesis-Master by Coursework
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering
• Online Access: https://hdl.handle.net/10356/177014
• Institution: Nanyang Technological University

Quantum Cascade Lasers represent a novel category of semiconductor lasers, distinctively crafted from multiple quantum wells/barriers to facilitate emission in the mid-infrared to Terahertz spectrum, spanning wavelengths approximately between 3 to 300 µm. The unique aspect of QCLs lies in their emission wavelength not being confined by the material’s bandgap but rather being adjustable through the precise engineering of the quantum wells/barriers’ thicknesses. This attribute has catapulted QCLs to the forefront of technology, enabling them to produce emissions at virtually any desired wavelength within the mid-infrared and Terahertz ranges. As a result, QCLs have found extensive utility in a diverse array of fields including, but not limited to, sensing, spectroscopy, imaging, atmospheric monitoring, security, defense, astronomy, and notably, free-space communications. This thesis endeavors to contribute to the advancement of QCL technology by introducing a high-performance, long-wavelength QCL, which has potential to be tailored for enhancing free-space communication systems. This dissertation focuses on the design, development, and comprehensive evaluation of a long-wavelength Quantum Cascade Laser (QCL). At the heart of this project is the ambition to construct a 13.6µm QCL utilizing diagonal transitions in conjunction with a three-phonon resonance design. This initiative aims to refine the device’s band structure and waveguide configuration, advancing towards the production of a laser that exhibits low loss and high optical gain, thereby ensuring superior performance. Through meticulous optical and thermal modeling and simulation, the study seeks to not only underscore the high efficiency of the long wave infrared QCL but also to explore its application potential in other wavelength domains.