Finite size effects in surface emitting Terahertz quantum cascade lasers

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Terahertz Technology

Background:

• Terahertz quantum cascade lasers (TQCLs) are crucial for various applications.
• Surface-emitting distributed feedback (SE-DFB) resonators are key components in TQCLs.
• Understanding resonator properties is vital for optimizing TQCL performance.

Purpose of the Study:

• To analyze surface-emitting DFB resonators in double-metal waveguide TQCLs.
• To investigate the impact of finite grating dimensions on resonator properties.
• To explore methods for optimizing TQCL lateral design and emission characteristics.

Main Methods:

• Numerical simulations incorporating absorbing boundary conditions.
• Analysis of finite grating length and width effects on resonances.
• Modeling of lateral resonator design to prevent higher-order transverse modes.

Main Results:

• Finite grating dimensions lead to finite surface losses for modes near the photonic band-gap.
• Lateral resonator design is critical for suppressing unwanted transverse modes and anti-guiding.
• Simulations show excellent agreement with experimental findings.

Conclusions:

• Finite-size effects in SE-DFB resonators significantly influence TQCL performance.
• Optimized lateral design is essential for efficient and high-quality Terahertz emission.
• The developed modeling and fabrication approach is versatile for various grating designs.