| CFD Research Corporation provides integrated
software tools and modeling expertise for multiscale, multiphysics design
of variety of optolectronic devices, including Quantum-Well (QW) based light
sources (VCSELs, Edge-Emitting Lasers), photodetectors
(MSM, p-i-n), and others.
Coupled Multiphysics Simulations of QW Lasers
O'SEMI (Optical-Semiconductor) software offers coupled multiphysics solutions
for simulations of QW lasers. The salient features include the following:
- O'SEMI input tools allow convenient and fast building models of complex
architectures of vertical-cavity surface-emitting lasers (VCSELs) and
Edge-Emitting Lasers (EELs).
- Parametric design and optimization tools, based on Python scripting.
- Automatic, script-based runs to obtain I-V and L-I characteristics.
- CFD-VIEW for detailed data and results visualization.
- Customized output of selected quantities to a text file.
- Multiple quantum wells, Multiple transverse modes.
- Transient simulation. Laser dynamics. Very fast solution.
CFDRC's Comprehensive model of VCSEL couples:
- Advanced optical models, including Weighted Index Method (scalar,
Body of Revolution) and Method of Lines (scalar and vectorial).
- The Semiconductor Device electric model, based on drift-diffusion
(DD) equations for carrier densities and energy balance (EB) equations
for carrier temperatures, resulting in spatially dependent current flow;
- Optical gain models: linear, logarithmic, advanced quantum physics,
curve fit to advanced model.
- Refractive index model: dependent on wavelength, temperature, quantum
well width, waveguide width, electric carrier concentration, and mole
fraction for compound semiconductors.
- Spatially and time dependent temperature solution included into gain
and refractive index models.
Such an advanced VCSEL model is required to predict realistic behavior
of various laser devices for the spatially nonuniform gain, due to current
crowding. Nonuniform gain has a visible effect on laser dynamics and parameters,
such as threshold gain. These modeling capabilities are not available
in most of the VCSEL simulators present on the market.
Steady-State Radial Distribution of Intensity in
Different Transverse Modes for VCSEL with 6-Micrometer Oxide Aperture
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Selected Snapshots of Transient Behavior of Total Optical Intensity
during the Multi-Transverse-Mode VCSEL Switching
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How the Optical Solution is
Obtained
The solution for VCSEL transverse and axial field
distribution in the modes as well as their lasing frequencies
consist of the solution of an eigenvalue problem for the Helmholtz
equation in cylindrical coordinates, and the boundary value problem
set by the boundary conditions at VCSEL layer and radial region
interfaces. For each mode, the photon rate equation is solved,
including optical losses, and spontaneous and stimulated emission
terms take into account spatially and time-dependent material
gain. Corresponding stimulated and spontaneous emission terms
are responsible for carrier relaxation in the electrical model.
At each time step, updated carrier concentration and temperature
are used in gain and refractive index models. A new solution for
optical modes is obtained using the updated gain and refractive
index.
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Example Results of VCSEL Simulations
Calculated Light-Current (L-I) and Current-Voltage (I-V)
steady-state characteristics for the intracavity VCSEL
Current Flow and Electron Density Distribution inside an
Intra-Cavity VCSEL Device
Transient Behavior of Multi-Transverse-Mode VCSEL. Photon Numbers in
Single Modes and Total Number of Photons in
the Cavity
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Coupled Full-Wave Optical and Semiconductor Photodetector Analysis
CFDRC offers an integrated, optical and electrical analysis tool for
high-fidelity modeling of photodetectors. It includes a full-wave optical
Electromagnetic Solver (EMAG) coupled with CFDRC's TCAD software. A user-friendly
interface allows for easy parametric analysis and optimization in the
design process. The interface also enables simulator use via the Internet.
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