Efficient method for the calculation of dissipative quantum transport in quantum cascade lasers

Area of Science:

• Quantum physics
• Semiconductor device physics
• Optoelectronics

Background:

• Quantum cascade lasers (QCLs) are crucial optoelectronic devices.
• Accurate simulation of quantum transport is essential for QCL design.
• Existing methods, like nonequilibrium Green's function (NEGF), can be computationally intensive.

Purpose of the Study:

• To present a novel and highly efficient method for calculating quantum transport in QCLs.
• To improve computational efficiency compared to traditional NEGF approaches.
• To enable the design and analysis of advanced QCLs.

Main Methods:

• The study employs the nonequilibrium Green's function (NEGF) framework.
• A key innovation is replacing lesser self-energy calculations with a quasi-equilibrium approximation.
• The method generalizes the Büttiker probe model to include specific scattering mechanisms.

Main Results:

• The novel method achieves orders of magnitude greater efficiency than fully self-consistent NEGF calculations.
• It provides accurate simulations for realistic QCL devices.
• Calculations for a new THz QCL design indicate functionality up to 250 K.

Conclusions:

• The developed method offers a significant computational advantage for quantum transport in QCLs.
• This efficiency facilitates the exploration of new QCL designs and operating conditions.
• The approach is validated by its application to a high-performance THz QCL.