Rapid Simulation of Photonic Integrated Circuits Using Verilog-A Compact Models

Abstract

Silicon-based electronic-photonic integration offers several opportunities for integrated circuits (IC) designers to innovate systems architectures that leverage the advantages of optical-domain signal processing and low-loss transmission in optical fibers. However, photonic integrated circuit (PIC) design tools have evolved from the numerical Maxwell field solvers and are completely disjointed from the electronic circuit simulation tools such as SPICE and Cadence Spectre. Thus there is a gap that needs to be filled by the IC community where they can instantiate photonic building blocks to form PICs and perform co-simulation with interfacing (Bi)CMOS electronic circuits. In recent work, Verilog-A compact models have been developed for photonic device building blocks that enable transient simulations of hybrid electronic-photonic components such as lasers, modulators and detectors. However, frequency sweeps of radio-frequency (RF) photonic filters remain unwieldy due to the long simulation times of stepped frequency transient simulations. In this work, we present complex frequency chirp based methods for rapid frequency-domain simulation of PICs. The trade-offs involved in selecting the simulation parameters for a given frequency response accuracy and simulation time are studied along with the impact of windowing and frequency chirp profile. The presented method can result in over $1000\times $ improvement in simulation time of frequency sweeps of higher-order RF photonic filter topologies.