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Harold

A hetero-structure laser diode model

Introduction

What is Harold?

HAROLD is an advanced hetero-structure simulator for modelling Fabry-Perot quantum well lasers with near-arbitrary vertical structure and layer compositions. It is based on well-established physical models which account for a large number of physical processes, thus enabling one to obtain a very comprehensive set of simulation results by which one can test and improve one’s laser designs. Devices can be simulated in both 1D (vertical) and 2D (vertical-longitudinal), operating under pulsed (isothermal) or CW (self-heating) conditions.

An additional XY Laser Module allows one to perform 2D lateral-vertical (XY) simulations starting from a full physical description of the laser’s cross-section. The cross-section can include graded etching and insulating layers, and have n and p-contacts on the same side. This ideal for studying the effects of lateral structure in both ridge waveguide lasers and SOI hybrid lasers

The Harold EAM Module includes a Quantum-Confined Stark Effect (QCSE) model allowing you to model electro-absorption modulators and electro-refractive modulators.

As well as being a laser simulator in its own right, Harold can export material models to Photon Design’s circuit simulator, PICWave, thereby allowing results from its detailed physical model to be incorporated into larger, more complex devices for fast simulation in the time domain.


Epitaxial structure

An epitaxial layer structure defined in Harold. Shown here are the core layers of a 4QW InGaAsP structure.

Material gain spectra

Material gain spectra for a set of carrier densities from a simulation of an AlGaAs SQW epilayer structure -
note the second gain peak which occurs at higher carrier densities.
Such material gain spectra can be exported to Photon Design’s circuit simulator: PICWave.

Current spreading

XY current density vector plot for ridge waveguide laser – illustrating the current spreading that occurs
as the current flows out of the ridge and down to the active region