# 2D ring resonator

A ring resonator is a type of optical resonator that is used to filter and manipulate light waves in a variety of applications, such as in telecommunications, sensing, and quantum computing. It consists of a circular waveguide in which light is confined and guided along the circumference of the ring, with the help of a waveguide coupler or a directional coupler that allows light to enter and exit the ring. The light circulating inside the ring resonator undergoes constructive or destructive interference, depending on the wavelength of the light, resulting in a resonant condition at certain frequencies. This allows the ring resonator to act as a narrowband filter or a wavelength-selective element, which can be used to transmit, reflect, or drop specific wavelengths of light. Ring resonators are widely used in photonic integrated circuits (PICs) due to their compact size, high efficiency, and low power consumption.

This is a simple example of using Tidy3D to perform a 2D simulation of a ring resonator side coupled to a dielectric waveguide. With a center wavelength of 500 nm and 10 nm resolution, this is a challenging FDTD problem because of the large simulation size and the large number of time steps needed to capture the resonance of the ring. However, it can be easily handled with Tidy3D.

To view the full example in Python, please click here (opens new window).