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A hetero-structure laser diode model

Hybrid Silicon Laser Model

Simulation with Harold XY software

Harold’s XY Laser Module can be used to simulate Silicon-On-Insulator (SOI) hybrid lasers. In this example we simulate an hybrid silicon laser based on a design by UCSB.

The structure has a III-V mesa region with an MQW AlGaInAs active region bonded to an SOI waveguide. The structure is ~70um wide in total with a 4um-wide central current channel, below which is an Si rib width surrounded by air channels on either side. The device was simulated in Isothermal mode (pulsed operation) from 0 to 500mA bias. 

XY Cross-section
2D XY Simulation – basic characteristics
2D XY Simulation – optical mode
2D XY Simulation – profiles/current spreading

XY Cross-section

The figure below shows the SOI hybrid structure that was set up in Harold.  

SOI cross section

SOI hybrid laser cross-section in Harold XY

2D XY Simulation – basic characteristics

Like a Harold simulation, an XY simulation yields the basic characteristics of the device, such as the power-current relation for different temperatures. It is shown in the figure below for the simulated SOI hybrid laser structure.

LI curves

LI curves for CW operation, for ambient temperatures 15, 25, 35 and 45 deg C

2D XY Simulation – optical mode

The XY Laser Module has a 2D FDM mode solver. The figure below shows the optical mode confined in this silicon rib waveguide; part of it overlaps with QWs, which provide optical gain for the lasing mode. 

SOI mode

Close-up of the ridge and computed optical mode in Si rib, which has a small overlap with QWs Γ=0.015

2D XY Simulation – profiles/current spreading

In addition to basic device characteristics, an XY simulation yields numerous 2D profile results. A selection of those obtained from the SOI hybrid laser simulation are shown below. 

Temperature profile

XY temperature profile for I=0.2A with ambient temperature of 45 deg C

Current density
Current spreading in SOI hybrid – current flows from p-contact, down the ridge,
through the QWs then laterally along n-InP layers to side n-contacts

Modelling a tapered hybrid laser with PICWave

You can model more complex geometries of hybrid lasers including tapered hybrid lasers (circuit shown below) using a combination of Harold and PICWave.

Tapered silicon laser diode circuit