# Edge coupler

Fiber-to-chip couplers are essential components in photonic integrated circuits (PICs) that need to couple in/out light using optical fibers. However, the huge mismatch between the mode sizes of a single mode fiber (≈10 in diameter) and a silicon wire waveguide (220 x 500 nm) can cause significant coupling loss if they are coupled directly. For this reason, the design of the fiber-to-chip coupling devices is critical for the whole system’s performance and needs to be carefully accomplished. There are two main categories of fiber-to-chip optical coupling devices: grating couplers, where the optical fiber is positioned perpendicularly to the chip plane; and edge couplers, which allow in-plane light coupling by the direct alignment between the fiber and the integrated waveguide facets.

In this example, we will show an example of using Tidy3D to evaluate the performance of edge couplers built using inverted taper mode transformers of linear, quadratic, and exponential profiles. We will also see how to set up a Gaussian beam (opens new window) to simulate the field launched by a lensed fiber and the use of Batch (opens new window) simulations to perform parameter sweeps.

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

To view the example in our web GUI, please click here (opens new window).