Modeling and Simulation of Free Space Optoelectronic Systems Timothy P. Kurzweg Jose A. Martinez Steven P. Levitan Donald M. Chiarulli University of Pittsburgh Philippe J. Marchand Susant Patra Lee Hendrick Xuezhe Zheng University of California San Diego Funding DARPA: F / NSF: ECS

What’s the Problem O/E information processing systems are difficult to design: –Heterogeneous systems –Expensive to prototype –Hard to simulate SLM 4f Imaging 4f Imaging Detectors Driver Electronics VCSEL Array Digital Logic Amplifiers

Chatoyant A system level O/E CAD tool to predict performance and analyze technology vs. architecture trade-offs without costly prototyping Develop 1st order analytical, empirical, and lumped-parameter models for optoelectronic components Develop a hierarchical & modular software environment using Ptolemy engine input spot pattern output spot pattern VCSEL source array optical path Spatial light modulator Gaussian beam cross sections Detector array Single channel end-to-end dynamic response

Models of Components Analytic models –Physics based Empirical models –Experimental data fitting Derived models –Parametric models extracted from (or verified by) lower level tools Response Surface Models (lumped parameter) O u t p u t P o w e r ( m W ) Input Power(mW) 2.5V 4V V Driver PP Pout Vdd Pin Stage1

Traditional small signal model analysis is invalid: –square waves –saturating drivers Use large signal models with dynamic time resolution: –achieves high accuracy at low computation cost Maintains a homogeneous simulation environment Piecewise Linear Model of Time with CMOS Electrical Drivers CMOS Large Signal Models High frequency response in Chatoyant for a cascade driver configuration (f = 600 MHz & C ld = 1fF). Input Stage 1 OutputStage 2 Output

Model Response in Chatoyant Chatoyant’s driver system High frequency response in Chatoyant shows a very close match to the Spice counterpart (f = 600 MHz & C ld = 1fF). Spice’s Response MHz (Load 1fF) InputOutput

Gaussian Beam propagation Static Simulation of Gaussian Beam Propagation Gaussian Beams On Detector Array

Simulating an NxN Optical Transpose Interconnect System (OTIS) (0,6) (6,0) 64 x 64

Dynamic Simulation: Detector Response Detector OutputEye Diagram

BER Modeling BER = ps BER=  A

Mechanical Tolerancing

VCSEL Alignment Tolerance mm 20 mm VCSELs = 10 o or 1.55  m waist Detectors = 80  m 1.85  m waist Shifted by  m Planar/Convex Lenslets Radius = 172  m n LENSLET = 1.51 Free Space - n = 1.0 Spacing for the VCSELs, Lenslets, and Detectors is all 500  m. Sapphire n=1.7589

Conclusions & Future Work Current Chatoyant features: –Dynamic and Static Simulations - BER, Insertion Loss, Crosstalk, Mechanical Tolerancing and Alignment –Architecture / Technology trade-offs What to do next? –Interfaces to/from low level electronic, optical, thermal & mechanical tools - Response Surfaces –Non-sequential surfaces, multiple time bases, & multiple energy domains - New simulation engine? Composite CAD Modeling: –Real data on emerging devices for models –Quick feedback to/from system designers Need to work closely with both device and system designers!