OptSim Circuit for PIC Design

OptSim Circuit provides an ideal, technology-agnostic platform for modeling optical systems and photonic integrated circuits (PICs) that operate with coupling and feedback of different optical and electrical signal paths. The graphical user interface (GUI) shared with our award-winning OptSim tool offers a more natural user experience to test and optimize performance of PICs at the system level.

Foundry PDK-based schematic in OptSim Circuit to generation of mask for fabrication

Foundry PDK-based schematic in OptSim Circuit to generation of mask for fabrication: 
400G coherent transceiver PIC design

In addition to supporting custom and foundry PDKs in circuit simulations, OptSim Circuit comes with a rich library of PIC elements including, but not limited to, bidirectional waveguides, bidirectional couplers and connectors, modulators, optical sources (lasers and VCSEL), and photodiodes (PIN and APD). Measurement and plotting tools are supplied, such as optical and electrical scopes, signal, spectrum and eye diagram analyzers, Q-factor and BER estimators, power meters, etc. OptSim Circuit's intuitive representation of repeating and hierarchical elements provides brevity and efficiency to the layouts. For example, you can create custom components and organize and reuse them in the PIC layout.

Estimating performance bounds in OptSim Circuit due to wafer-to-wafer (WTW) and run-to-run (RTR) foundry process variations

Estimating performance bounds in OptSim Circuit due to wafer-to-wafer (WTW) and run-to-run (RTR) foundry process variations

OptSim Circuit takes into account bidirectional propagation of both optical and electrical signals. This makes it possible to model complex signal interactions such as reflections and resonance in PICs that otherwise are impossible to model in conventional systems modeling tools.

OptSim Circuit's extensive documentation includes an installation guide, user guide, models reference guide and application notes. The product also includes a number of pre-supplied PIC design case studies including high-speed coherent and non-coherent transceivers, all-optical data center switch fabrics, sensors, segmented- and travelling wave Mach-Zehner modulator designs, PICs using foundry- and custom PDKs, and more.

Schematic-Driven PIC Design Flow

The designer’s ideas are naturally expressed at the circuit level, where the signal behavior is modeled and prototypes can be simulated. Once the desired functionality is achieved, it can be translated into a layout representation by leveraging process design kit (PDK) libraries that have both circuit and layout representations. 

Schematic-driven PIC design: from idea to mask

Bidirectional Interface with OptoDesigner

The bidirectional interface between OptSim Circuit and OptoDesigner provides users with a seamless path from idea to realization, from function to mask as well as from masks to circuits for verification of post-layout circuit performance due to routing parasitics and crosstalk. 

Bidirectional interface with OptoDesigner allows post-layout circuit performance verification taking into account routing induced optical parasitics and crosstalk

Design and manufacture a photonic integrated circuit

  • Schematic-driven functional design done in OptSim Circuit
  • Mask generation done in OptoDesigner
  • Process design kit (PDK) from foundry contains characterization at both circuit and layout abstraction levels
  • RSoft Component Design Suite is used to enhance existing PDK, or build a new one

An example of the schematic driven PIC design flow using a commercial foundry process design kit (PDK) is illustrated below. 

Example of the Schematic Driven PIC Flow: AIM PDK-based QPSK Transmitter

Example of the Schematic Driven PIC Flow: AIM PDK-based QPSK Transmitter

The I-Q modulator (top left) based quadrature phase-shift keying (QPSK) transmitter is implemented in OptSim Circuit using micro-ring modulators for in-phase and quadrature phase components (lower left). Once the simulation results (lower right) match designer’s objectives, an OptSim Circuit netlist is used to generate the corresponding layout in OptoDesigner (top right).

Although photonic foundries continue to enhance support for wider arrays of active and passive photonic PDKs based on different technologies, there are times when the ability to generate custom, proprietary PDKs and use them in circuit simulations and mask generation are important. Whether the motive is to generate intellectual property (IP), or to supplement an existing PDK, OptSim Circuit and the RSoft device modeling tools offer virtually limitless means for creating custom components and PDKs and deploying them in PICs.  The interface with OptoDesigner then uses the OptSim Circuit netlist to generate the layout.

Example  of the schematic-driven PIC Flow: AIM and custom PDK-based WDM receiver

Example of the schematic-driven PIC Flow: AIM and custom PDK-based WDM receiver


  • Offers a comprehensive, technology-agnostic pathway to PIC ecosystems, starting from the development of concepts to foundry PDK-based schematics, and leading to the creation of masks ready for fabrication
  • Enables evaluating the impact of post-layout routing parasitics and crosstalk on functional behavior of the circuit
  • Provides a unified platform to evaluate and optimize the impact of PIC performance on the overall system when used with the OptSim tool
  • Delivers powerful options for design setup, data visualization, plotting and management of project resources


  • Single- and multi-stage Photonic Integrated Circuits (PICs)
  • Transceivers for coherent and non-coherent fiber optic communication systems
  • Segmented-electrode (SE) and traveling-wave Mach-Zehnder modulators (TW-MZM), optical filters, ring resonators, ring modulators
  • All-optical data center switching
  • Photonic sensor PICs
  • PICs for photonic computing, optical neural networks and life sciences
  • Photonic systems with multipath interference (MPI), reflections and resonances


  • Extends OptSim’s system modeling capabilities to include PICs
  • Models bidirectional propagation for both optical and electrical signals, forward and backward propagating reflections and resonance
  • Supports electronics-photonics cosimulation via supplied models and cosimulation with HSPICE and SPICE
  • Supports PDKs from leading photonic foundries
  • Includes library of PIC elements such as bidirectional waveguides, bidirectional couplers and connectors, light sources, modulators and photo diodes
  • Models multipath Interference (MPI) from network and PIC elements
  • Supports reusable user-defined components and hierarchies
  • Offers flexibility to create custom models using cosimulation with MATLAB
  • Provides an intuitive graphical user interface, comes with a number of options for data visualization, management of project resources, as well as exporting data and for co-simulation with external tools

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