Detecting gravitational waves with light

The strong evidence for low-frequency gravitational waves from pulsar timing arrays (PTAs), published in 2023, has widened the scope for teaching about gravitational wave astronomy. This article provides a simple, unified overview of the detection of gravitational waves using light waves that encompasses the recent PTA detections, the by-now classic interferometric detections using LIGO and similar detectors, and the yet-to-be-accomplished detections using long-arm detectors like the spaceborne LISA. The presentation is at a level accessible for undergraduate students. The influence of gravitational waves on light is derived in a way that makes use only of basic gravitational wave properties and Einstein's equivalence principle.