Active Device Utilities and Multi-Level Simulation An Overview If you have technical questions, please contact evanh@synopsys.com 2016 Synopsys, Inc. 1
Outline Introduction Multi-Physics Utility Carrier Effects Solar Cell Utility Lasermod Option Tapered Laser Utility Multi-Level Simulation 2016 Synopsys, Inc. 2
Introduction Some active applications may require multiple tools. These tools may be used together manually, or automated via a utility: Utility Interaction involves 1 or 2 directional data flow: Active Device Passive Device Multi -Physics Utility (Carrier effects) Solar Cell Utility ( Lasermod option) Tapered Laser Utility Multi-Level Interaction involves 1 directional data flow: Active (or Passive) Device System OptSIM-LaserMOD (Parameter Extraction) ModeSYS-LaserMOD (Near/Far-Fields) 2016 Synopsys, Inc. 3
Introduction A utility is an automated process for addressing a particular application (solar cell, modulator, etc ). It is not a simulator, but uses one or more simulators to generate specific data. It also provides some post -processing of the data to generate application specific performance results. 2016 Synopsys, Inc. 4
Introduction Operational Scheme of a 2D Utility: Active Device Simulator Takes the mode(s) or field from a passive tool & produces a complex index that includes the various perturbations from carriers & material gain/loss. (each 2D slice ) Passive Device Simulator Takes the complex index, merges it with the unperturbed structure, and solves for the mode(s) or field. 2016 Synopsys, Inc. 5
Introduction Operational Scheme of a 3D Utility: A collection of 2D slices are simulated iteratively until convergence is reached. 2016 Synopsys, Inc. 6
Introduction There are 2 types of Multi-Level Simulation, extraction and data file exchange: Laser modeling may be achieved jointly with the device and system tools via the BestFIT Laser Toolkit, which can extract system level model parameters from active device level simulation results. Field and mode profiles generated by device tools may be passed to ModeSYS to study spatial effects at system level. Parameter Extraction (BestFit Toolkit) Modes & Transfer Functions 2016 Synopsys, Inc. 7
Outline Introduction Multi-Physics Utility Carrier Effects Solar Cell Utility Tapered Laser Utility Multi-Level Simulation 2016 Synopsys, Inc. 8
Multi-Physics Utility The Multi-Physics Utility includes the following physical effects: Electro-optic Thermo-optic Stress-optic Carrier effects Carrier effects require the use of LaserMOD. They are necessary for simulation Electro -absorptive and Electrorefractive Modulators. Of current interest are those implemented in silicon -on-insulator (SOI). 2016 Synopsys, Inc. 9
Multi-Physics Utility Multi-Physics Utility (carrier effects) Extends 2D active device simulation of free carrier effects to 3D for the case of waveguide circuits. Uses BeamPROP + LaserMOD. Addresses design improvements such as: Modulation speed and ON/OFF contrast, Compactness of geometry. Arbitrary waveguide circuit layouts can be accommodated. All simulations handled transparently by the RSoft CAD. 2016 Synopsys, Inc. 10
Multi-Physics Utility In some cases, modulator performance can be determined by an analytic expression: (1-cos(K0*(Neff-Neff0)*L))/2 In others, a 3D optical solution is required. The 3D structure can be constructed from a set of 2D complex index cross-sections obtained from active simulation, at a given applied bias. 3D propagation can then be performed with BPM. 2016 Synopsys, Inc. 11
Multi-Physics Utility Setting up the carrier effect is nearly identical to setting up an electrooptic problem. The desired structure is drawn and electrodes are place appropriately. The voltage is then set in the control parameter of the bias electrode(s). Project materials are set as in the Material Editor, as before, but when carriereffects are used, an active semiconductors structure, with doping and alloy composition, must be defined. This is done on the Semiconductor Tab. 2016 Synopsys, Inc. 12
Multi-Physics Utility The following example is a ridge waveguide implemented in SOI. A voltage bias is applied to the electrode on top of the ridge. This voltage may be controlled from the utility dialog. electrode 2016 Synopsys, Inc. 13
Multi-Physics Utility The Multi-Physics Utility will simulate the steady-state behavior at the specified voltage. But the time/frequency response is also available, and is enabled from the Carrier Options Dialog, within the utility. 2016 Synopsys, Inc. 14
Multi-Physics Utility When the Multi -Physics Utility is run directly from the dialog, the real & imaginary index perturbations that result from the applied voltage, are generated. Additionally, the intermediate solutions (electron & hole densities, and electrostatic potential) are also produce. 2016 Synopsys, Inc. 15
Multi-Physics Utility Furthermore, I-V, C-V, and R-V plots are generated, If enabled, the frequency response will be output as well. All results will be displayed by the DataBROWSER, which is invoked automatically at the end of the simulation. 2016 Synopsys, Inc. 16
Multi-Physics Utility Standard propagation and mode solving will also reflect the presence of carrier effects, provided these effects have been enabled in the Utility Dialog. For example, the mode calculations shown below, are at different voltages, and therefore have different Neff s. V=0 (volt) V=1 (volt) 2016 Synopsys, Inc. 17
Multi-Physics Utility A simple validation example is now presented: an SOI -based Mach-Zehnder Modulator. Reference: Modeling and Characterization of Mach-Zehnder Silicon Electrooptical Modulators, G.-R. Zhou et.al., CLEO/QELS 2008. The simulation is conducted as follows: The Neff of the waveguide vs applied voltage is determined from a rigorous simulation using the Multi-Physics Utility. The final modulator transmission characteristics are then tabulated from an analytic function of the waveguide Neff. A full BPM approach could also have been used to determine the modulator transmission, but with a simulation time cost. 2016 Synopsys, Inc. 18
Multi-Physics Utility The device is an MZ modulator with.25mm long branches. The waveguide is silicon with a 500nm x 200nm cross-section, set between lateral n- & p-contacts. The voltage on one contact varies between 0 and 1.2 Volts, but remains 0 Volts on the other. V=0 volts V=0-1.2 volts contacts 2016 Synopsys, Inc. 19
Multi-Physics Utility Simulation results for the I-V curves and modulator transmission characteristics are shown below. Measured and S-Device simulation Multi-Physics Utility simulation 2016 Synopsys, Inc. 20
Multi-Physics Utility Simulation results for the frequency response ( S 21 2 ) are shown below. All show the 3dB point to be around 0.4GHz. Measured and S-Device simulation Multi-Physics Utility simulation 2016 Synopsys, Inc. 21
Outline Introduction Multi-Physics Utility Solar Cell Utility Lasermod Option Tapered Laser Utility Multi-Level Simulation 2016 Synopsys, Inc. 22
Solar Cell Utility This utility computes the cell efficiency of a solar cell device. It will also compute the collection efficiency if LaserMOD used, otherwise this must be input by the user. The optical confienement is computed via DiffractMOD or FullWAVE. The incident spectrum may be selected as the Solar Spectrum at sea level or input via User Defined file. Electrical characteristics are determined via the ideal diode equation or by LaserMOD simulation. Simulation results are automatically combined to produce cell efficiency and other outputs of interest. 2016 Synopsys, Inc. 23
Solar Cell Utility For example, optical confinement and thus cell efficiency may be enhanced by randomly textured interfaces. Simulation of this requires FDTD. Sunlight 2016 Synopsys, Inc. 24
Solar Cell Utility Absorption is tabulated in a particular region via the Absorption Monitor (FullWAVE) or in the entire structure. This is done for a sampled set of wavelengths within the incident spectrum (two wavelengths are shown below. 2016 Synopsys, Inc. 25
Solar Cell Utility From this absorption, Jsc (short circuit current) is calculated. From Jsc and several input parameters such as collection efficiency and Voc (open circuit voltage) the Ideal diode equation may be used to generate an I-V curve. or Using absorption at each wavelength, the photo-generated carrier distribution is obtained and the electronic transport, is solved leading directly to a nonidealized I-V curve. Collection efficiency is output. From the I-V curve, the optimum bias point can be found, giving filling-factor and cell efficiency. 2016 Synopsys, Inc. 26
Outline Introduction Multi-Physics Utility Solar Cell Utility Tapered Laser Utility Multi-Level Simulation 2016 Synopsys, Inc. 27
Tapered Laser Utility Most active device characteristics can be extracted from 2D simulations, but some cases require 3D, for example: When the lasers geometry varies along the device. Tapered Ridge Tapered electrode When 3D spatial effects are of interest (even in straight ridge). Filamentation Transverse + Longitudinal spatial hole burning 2016 Synopsys, Inc. 28
Tapered Laser Utility The Tapered Laser Utility extends the 2D active device simulation to 3D. It can analyze the optical and electronic properties of waveguide lasers with straight and tapered (or slowly varying) sections. It provides a Self-consistent simulation using BeamPROP for the Optical propagation, and LaserMOD for the electronic transport. Outputs include the field at every slice, L -I-V curves, and the far field from each facet. 2016 Synopsys, Inc. 29
Tapered Laser Utility The active simulation produces complex index. The passive simulation propagates the field. The utility ensures self -consistency for all the slices. 2016 Synopsys, Inc. 30
Tapered Laser Utility The full structure is comprised of all the slices, which are coupled to each other via the propagating field. The electrical simulations of each slice are independent from each other. 2016 Synopsys, Inc. 31
Tapered Laser Utility In the gain guiding example distributed with the software, the tapered region is defined purely by the top (tapered) electrode. The straight section is defined by a ridge (and electrode) 2016 Synopsys, Inc. 32
Tapered Laser Utility Since the tapered region is defined purely by the top electrode, confinement is due to gain guiding there. 2016 Synopsys, Inc. 33 Shown to the right are slices of the steady-state optical field near the facets of the straight and tapered sections. The field near the facet of the tapered section (top) shows the formation of filaments.
Tapered Laser Utility As a validation example, a straight waveguide section was simulated using the Utility. These results are essentially 2D and may be compared to the those coming directly from LaserMOD. The I-V and L-I curves are shown below. 2016 Synopsys, Inc. 34
Outline Introduction Multi-Physics Utility Solar Cell Utility Tapered Laser Utility Multi-Level Simulation 2016 Synopsys, Inc. 35
Multi-Level Simulation Active Device Simulator rigorous solution of electronic transport, material gain, & optics System Level Simulator many components, but simpler models System level laser model Laser Parameter Extraction (BestFit Toolkit) 2016 Synopsys, Inc. 36
Multi-Level Simulation Device Performance Best-Fit Laser TM Laser Parameter Extraction OptSim TM System Level Simulator LaserMOD TM Active Device Simulator Device to SPICE Laser SPICE-like Electrical Circuit System Performance 2016 Synopsys, Inc. 37
Multi-Level Simulation The second type of multi-level interaction involves the passing of spatial data from device to system level. For example, the effects of imperfect coupling between a VCSEL and a multi-mode optical fiber link may be simulated. LaserMOD TM Active Device Simulator ModeSYS TM System Level Simulator 2016 Synopsys, Inc. 38
Multi-Level Simulation The near fields or far fields may be simulated in the device tool (LaserMOD). These can be passed to multi-mode system tool (ModeSYS). Then various offsets and angles may be applied to the Spatial Coupler model in ModeSYS to enable the analysis of the impact due to misalignment. The system performance in the presence of varying misalignments can be determined without rerunning the device level simulation. 2016 Synopsys, Inc. 39
Q & A Thank You