Photonic Integrated Circuits Design

Photonic Integrated Circuit (PIC) design is the process of creating optical circuits on a semiconductor chip. These circuits integrate components such as waveguides, modulators, detectors, and lasers to manipulate light on-chip. PIC design involves system architecture, optical simulations, layout creation, and preparation of fabrication-ready design files for photonic foundries.

A photonic design house provides engineering services for the design and development of PICs. This includes translating system requirements into optical circuit architectures, selecting foundries and packaging partners, designing photonic components, performing simulations, and preparing layouts compatible with foundry fabrication and packaging processes. Epiphany supports companies in developing PIC designs from first ideas (such as early architecture definition) all the way to fabrication-ready layouts.

PICs can be designed on several material platforms depending on the application and requirements. Common platforms include Silicon on Insulator (SOI), Silicon Nitride (SiN), Indium Phosphide (InP), Lithium Niobate (LNOI), Aluminum Oxide (AlOx), etc. Each platform offers different advantages in terms of loss, integration capability, modulation speed, wavelength range and costs. Learn more about PIC platforms on our Guide to PIC Technologies. As a fabless design house, Epiphany works across multiple PIC platforms, enabling cross-platform design and technology evaluation.

A photonic Process Design Kit (PDK) translates the capabilities and processes of a foundry onto design software (so-called electronic design automation, EDA). PDK can provide different capabilities from basic layout instruction and design rules to libraries that contain already validated photonic components and even simulation models. Often it allows designers to build circuits using components that are known to be compatible with the manufacturing process. Epiphany is also supporting foundries with PDK development and maintenance. Learn more about our Foundry Enablement service here.

Hybrid or heterogeneous integration combines different materials or photonic technologies within a single system to achieve functionalities that cannot be realized in a single platform alone. For example, low-loss waveguides in Silicon Nitride may be combined with active components such as lasers or modulators implemented in Indium Phosphide or Lithium Niobate. System-level photonic design must consider optical coupling, packaging constraints, and fabrication compatibility when combining different technologies.

Companies typically outsource PIC design when they lack in-house photonics design expertise or capacity and want to accelerate their development. External design houses can support early architecture development, component design, layout implementation, and foundry preparation, allowing teams to focus on system development and product integration. At Epiphany Design, the team performs many tape-outs every month across different PIC platforms and applications, which provides broader practical experience across foundries, technologies, and design approaches.

A PIC design project typically includes the following stages:

• System architecture and specification definition
• Optical circuit design and simulation
• Subsystem design using foundry building blocks and custom components
• Layout implementation using the foundry PDK
• Design rule checking and verification
• Preparation for fabrication (tape-out)  

Depending on the project, Epiphany may also support system modeling, integration strategy, and preparation for multi-project wafer (MPW) runs or dedicated runs.

Design timelines depend on the circuit complexity and maturity of the concept. Simple PICs may take a few weeks to design, while complex multi-functional chips may require several months. Additional time may be required for simulation, verification, and preparation for foundry tape-out.

While not strictly necessary, most modern PIC designs are developed using a Process Design Kit (PDK) provided by the photonic foundry. The PDK contains validated building blocks, process rules, and simulation models that ensure designs are compatible with the fabrication processes.

Epiphany works with multiple foundry PDKs and supports design flows adapted to each platform.

In some cases, a design can be adapted to another foundry or platform, but this typically requires redesign of components and layout elements. Different foundries use different waveguide geometries, component libraries, and fabrication rules. As a result, migration usually involves revalidation of optical performance and design rule compliance. Foundry building blocks must generally be replaced, or re-designed if necessary. Cross-platform design expertise is often required to perform this process efficiently. To make the transfer of designs easier between different foundries and technologies Epiphany works with Design Modules to give their/our customers the flexibility they need.

PIC design typically uses photonic design environments similar to Electronic Design Automation (EDA) tools. These tools allow schematic design, layout generation, and design rule checking. They are often combined with simulation tools for optical performance and system verification.

Epiphany uses industry-standard photonic design tools and simulation environments to develop fabrication-ready designs from layout, physical layer simulation, circuit simulation to design verification.

Yes, certain photonic platforms such as Indium Phosphide support monolithic integration of lasers, modulators, and detectors. Other platforms may combine active and passive devices through hybrid or heterogeneous integration approaches.

A typical project starts with a technical discussion about the application, performance targets, and preferred technology platform.

Based on this information, the design scope can be defined, including system architecture, simulation needs, and the target fabrication route. The outcome is usually a design plan leading to a fabrication-ready PIC layout.

The cost of PIC fabrication depends on the platform, foundry, chip size, and whether the design is part of a multi-project wafer run or a dedicated wafer.

Multi-Project Wafer (MPW) runs significantly reduce the cost of early prototypes. Later project stages are usually more expensive than earlier ones.

Fabrication costs more than design, packaging and testing often costs more than fabrication, dedicated runs cost more than MPW runs, and so on.

A multi-project wafer (MPW) run is a shared fabrication approach where different chip designs from multiple users are combined onto a single wafer and processed together in one manufacturing cycle. Instead of each project requiring its own dedicated (and more costly) fabrication run, participants share the costs of the manufacturing. Their individual designs are placed on different sections of the same mask set, allowing everyone to benefit from the same standardized process flow and proven building blocks. This makes MPW runs especially attractive for prototyping photonic integrated circuits, testing new concepts, or validating designs before scaling up.

Companies often collaborate with photonic design houses when developing a new photonic technology, evaluating fabrication platforms, or when internal teams lack specialized PIC design expertise or capacity.

External design support can accelerate development and reduce risk when preparing designs for fabrication. A thorough planning and design phase reduces the number of expensive iterations needed to make a product.