Aspects of cavity engineering in THz quantum cascade laser frequency combs

Area of Science:

• Physics
• Quantum Optics
• Semiconductor Lasers

Background:

• Terahertz (THz) quantum cascade laser (QCL) frequency combs are crucial for spectroscopy, imaging, and quantum technologies.
• Custom modifications to QCL cavities, like dispersion engineering and tapered waveguides, significantly impact laser performance.
• Detailed device modeling is essential for advancing THz QCL frequency comb technology.

Purpose of the Study:

• To present a numerical model based on the Maxwell-density matrix formalism that accurately captures cavity effects in THz QCLs.
• To provide a deeper understanding of QCL dynamics and enable the design of cavities for specific laser applications.
• To explore how waveguide engineering influences frequency comb generation and properties.

Main Methods:

• Implementation of a numerical model using the Maxwell-density matrix formalism.
• Inclusion of detailed cavity effects, such as dispersion engineering and waveguide geometry.
• Simulation of THz QCL dynamics under various waveguide configurations.

Main Results:

• The model successfully captures the influence of custom cavity modifications on THz QCL behavior.
• Waveguide engineering, including dispersion compensation and field enhancement, can stabilize frequency comb operation from multimode states.
• The study demonstrates the ability to shape frequency comb properties like bandwidth and mode spacing through cavity design.

Conclusions:

• The developed numerical model offers a powerful tool for understanding and designing THz QCL frequency combs.
• Cavity engineering presents a viable strategy for tailoring frequency comb characteristics for advanced applications.
• This work paves the way for custom-designed THz QCLs for specialized spectroscopic and quantum technological needs.