The pioneering quantum dot gain model arrives to Harold with this latest update along with grand improvements across the board including multi-threading for faster simulations and multi-junctions for advanced designs in VCSELs.

We’re excited to continue our contributions to the advancements being made with these high temperature operating lasers and seeing as well as integration into silicon/ TFLN epitaxy.

The launch of Harold’s Quantum Dot Module:

• Quantum dot ensembles can now be added to quantum well layers with either lens or pyramid shapes and a distribution of sizes.
• An 8 band k.p Schrodinger solver provides energy levels including a 3D stress strain model.
  Quantum dot simulations are integrated into Harold’s existing simulation capability.
• Development begins immediately on a Harold to PICWave export for quantum dot epitaxies making Photon Design the first commercial simulation offering for full 3D quantum dot lasers.

Efficiency Improvements
Harold now fully supports the use of multiple CPU cores increasing possible simulation speeds. The addition of State Files now allow simulations to be paused and resumed where they left off. Quantum dot ensemble simulations can be re-used between different simulations if there are no changes to the ensemble

Multi-Junctions and Tunnel Junctions
 Added support for simulating multi-junction devices. These devices have multiple (M)QW active regions separated by bulk and tunnel-junction layers. Further, a non-local band-to-band tunnelling model is introduced providing a more realistic description of the tunnelling processes within tunnel-junction layers.

Further:

Gain, VCSEL, and Harold XY:

• The bandgap and lattice constant can now be obtained from the Epitaxial Layers Structure via the command line.
• Improved handling of active regions containing non-uniform QWs, asymmetric barriers, and/or multiple adjacent QW layers.

VCSEL and Harold XY:

• The electric field is now computed in insulator layers. This means that the capacitive effects of buried insulators are now included in the simulation.
• Spectral results can now be plotted against either wavelength or energy.
• Added QW Profile results. These are 1D profiles of the QW band structure and wavefunctions (equivalent to Quantum Well Wavefunction results in HaroldGain).
• Added QW k.p results. These show the dispersion of the electrons and holes in the QWs as a function of in-plane wavenumber.
• Improved convergence of simulations containing pn-blocking buried heterostructures

Harold XY:

• Added operationalWavelength simulation option. This allows the user to choose whether to use a fixed lasing wavelength or to allow the lasing wavelength to follow the peak of the gain spectrum.
• Added support for running 1D simulations in HaroldXY using a single lateral mesh cell.