HAROLD is an advanced heterostructure simulator for modeling Fabry-Perot quantum well lasers with near-arbitrary vertical structure and layer compositions. HAROLD also includes a full 3D VCSEL model, taking into account optical, electrical, and thermal effects.

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  • Advanced laser simulations
  • Fabry-Perot cavity modeling in 1D (Y) and 2D (YZ);
    Pulsed (isothermal) or CW (self-heating) conditions;
    Harold XY: laser cross-section modelingGain curves export for laser / SOA modeling;
  • Self-consistent solution of Poisson Equation
  • With drift-diffusion, capture/escape models for electrons and holes;
  • Full XY or YZ solution of the heat flow equation
  • Power dissipation: Joule, non-radiative recombination, free carrier absorption, excess power distribution, mirror scattering and mirror absorption;
    Heat-sink overhang in 2D (YZ) calculations;
  • 2D+Z waveguide mode solver
  • Used to compute confinement factor and mode gain for TE and TM modes;
  • Capture/Escape balance equations
  • Used to describe thermal equilibrium between confined and unconfined carriers in QW regions;

  • Gain model for QW lasers
  • Function of wavelength, carrier concentration and temperature;
    Parabolic band approximation;
    Can compute both TE and TM mode gain;
  • Support of multiple QW structures (MQW)
  • Supports non-identical wells Schrödinger Equation solved over the whole MQW region to account for coupling between wells Wavefunction overlaps included in recombination and gain model;
  • Built in full-vector 3D cavity mode solver for multiple modes;
  • Built-in far-field calculator
  • Full 3D thermal heat-flow model;
    Self Consistent Poisson/drift-diffusion electrical model;
  • Miscellaneous
  • Models effect of strain (in QW and barrier layers) on the QW levels;
    Includes Shockley-Read-Hall, Auger, stimulated & spontaneous recombination;
    Non-injecting and absorbing mirrors;
    Material database of quaternary alloys; materials such as AlGaAs, InGaAsP, InGaAlAs, gold, copper, etc.;


  • FP Quantum Well lasers
  • Ridge waveguide lasers
  • SOI hybrid lasers
  • VCSELs


VCSEL Module

The VCSEL Module allows the calculation of multiple optical cavity modes, electrical drift diffusion, heat flow, and electron-photon interactions in a full 3D model.

Building on Photon Design’s decades of experience the VCSEL module provides a fully integrated design environment for the variety of the VCSEL types being used today, including QW materials, current blocking apertures, and more.