A multi-band, multi-level, multi-electron model for efficient FDTD simulations of electromagnetic interactions with semiconductor quantum wells

TL;DR

This paper introduces a novel multi-band, multi-level, multi-electron FDTD model for simulating electromagnetic interactions with semiconductor quantum wells, enabling efficient and accurate 2D and 3D nanophotonic device simulations.

Contribution

The paper presents a new computational model that combines multi-band and multi-electron approaches with explicit update schemes for efficient FDTD simulations of SQW devices.

Findings

Model accurately predicts optical gain spectra.

Simulation results match analytic band filling calculations.

Enhanced computational efficiency demonstrated in 2D and 3D simulations.

Abstract

We report a new computational model for simulations of electromagnetic interactions with semiconductor quantum well(s) (SQW) in complex electromagnetic geometries using the finite difference time domain (FDTD) method. The presented model is based on an approach of spanning a large number of electron transverse momentum states in each SQW sub-band (multi-band) with a small number of discrete multi-electron states (multi-level, multi-electron). This enables accurate and efficient two dimensional (2-D) and 3-D simulations of nanophotonic devices with SQW active media. The model includes the following features: (1) Optically induced interband transitions between various SQW conduction and heavy-hole or light-hole sub-bands are considered. (2) Novel intra sub-band and inter sub-band transition terms are derived to thermalize the electron and hole occupational distributions to the correct Fermi-Dirac distributions. (3) The terms in (2) result in an explicit update scheme which circumvents numerically cumbersome iterative procedures. This significantly augments computational efficiency. (4) Explicit update terms to account for carrier leakage to unconfined states are derived which thermalize the bulk and SQW populations to a common quasi-equilibrium Fermi-Dirac distribution. (5) Auger recombination and intervalence band absorption are included. The model is validated by comparisons to analytic band filling calculations, simulations of SQW optical gain spectra and photonic crystal lasers.