Advanced Photonics Seminar Series

The finite-difference time-domain (FDTD) method is a powerful full-wave simulation tool for solving Maxwell’s equations. It is widely used in modeling the behavior of light in nanophotonic devices. In this section, we introduce the fundamental concepts behind FDTD and how to use it to simulate a wide range of phenomena in photonics. As an example, we show how to compute the scattering cross-section of a dielectric sphere and benchmark it against Mie Theory.

Designing multimode devices can be a complex task. In this session, we present the tools available in Tidy3D that facilitate this process and enable precise control over mode excitation, decomposition, and tracking in dielectric waveguides. In a real device, we show the importance of modal decomposition analysis when designing multimode photonics.

Bragg gratings are periodic structures used in various optical systems. The periodicity allows Bragg gratings to reflect specific wavelengths of light while transmitting others. The key principle behind their operation is the Bragg’s condition. This section will introduce the Bragg condition and use Tidy3D to model a distributed Bragg reflector and cavity. Then, we will apply the same principle to integrated photonics and demonstrate the design of silicon waveguide Bragg gratings.

In this session, we review the theory behind photonic crystal (PhC) slabs and some of their possible applications. As a practical Tidy3D example, we show how to compute the photonic band structure of a PhC slab and how to simulate an ultra-high-Q, small-volume PhC defect cavity that is also optimized for efficient vertical light extraction.

“Inverse design” is a technique for automated photonic device design. The process involves mathematically defining a “figure of merit” for one’s device and then using gradient-based optimization to efficiently maximize this function with respect to a large number of design parameters. In this section, we introduce the basics of inverse design, discuss its connections to other techniques in deep learning, and give practical examples of how it is used to design photonic devices in Tidy3D.

In this presentation, we introduce TidyGrad, an innovative inverse design tool integrated with Tidy3D's GPU-accelerated FDTD solver. TidyGrad leverages automatic differentiation to streamline the design of photonic devices, enabling users to define objective functions in Python and compute gradients efficiently using the adjoint method. This approach simplifies the optimization process, allowing for the creation of high-performance, non-intuitive photonic structures. The presentation covers the fundamentals of inverse design, the implementation of TidyGrad, and practical examples demonstrating its application in photonics engineering.

PhotonForge is a unified platform for fabrication-aware photonic design. It accelerates your photonic device design process by seamlessly integrating with simulation tools, including Tidy3D FDTD, mode, heat, and RF solvers. With built-in access to foundry PDKs, PhotonForge simplifies the transition from design to fabrication. In this seminar, we will cover the basics of PhotonForge with an overview of its main concepts and how to get started quickly in photonic integrated circuit design.

This seminar provides an in-depth look at how foundry-provided Process Design Kits (PDKs) are integrated within PhotonForge to create accurate simulation models. Showcase how to leverage the technology stack to design new photonic components, incorporate them into their design library, and utilize technology updates to study the impact of fabrication variations on PIC performance.

This seminar explores the cutting-edge research and simulation techniques for designing and understanding nanophotonic structures intended for coupling to quantum emitters and topologically protected modes. We will discuss robust and emitter chirality-dependent light transport in a topological photonic crystal and topology optimization of a quantum emitter light extractor into an integrated waveguide, showcasing how these phenomena can be harnessed for next-generation photonic devices using Tidy3D.

This seminar explores how to perform fabrication-aware inverse design that accounts for worst-case scenarios and variability across process corners. We’ll cover practical patterns for structuring objectives, conducting sensitivity and tolerance analyses, and aligning simulation with hardware through process models and measurement-driven calibration.