Spoof plasmon waveguide enabled ultrathin room temperature THz GaN quantum cascade laser: a feasibility study

Area of Science:

• Semiconductor Physics
• Optoelectronics
• Quantum Electronics

Background:

• Quantum cascade lasers (QCLs) are crucial for generating coherent terahertz (THz) radiation.
• Achieving room-temperature operation in THz QCLs remains a significant challenge due to various loss mechanisms.

Purpose of the Study:

• To investigate the feasibility of a compact THz GaN/AlGaN quantum cascade laser (QCL).
• To explore the use of spoof surface plasmon (SSP) waveguides for room-temperature operation.
• To leverage the unique properties of GaN for enhanced laser performance.

Main Methods:

• Theoretical analysis and simulation of a five-period GaN/AlGaN heterostructure.
• Design of a spoof surface plasmon (SSP) waveguide for optical confinement.
• Modeling of laser state lifetimes considering phonon scattering mechanisms in GaN.

Main Results:

• A novel THz GaN/AlGaN QCL design with only five periods was proposed.
• The spoof surface plasmon (SSP) waveguide demonstrated sufficiently low optical loss.
• The QCL is predicted to reach threshold at an injection current density of approximately 6 kA/cm2 at room temperature.

Conclusions:

• The proposed THz GaN/AlGaN QCL design utilizing SSP waveguides is feasible for room-temperature operation.
• The inherent properties of GaN, such as large optical phonon energy, are beneficial for QCL performance.
• This work paves the way for compact and efficient room-temperature THz sources based on III-nitride materials.