Delaying light is sometimes used for a buffer in optical networks and signal processing, it is also used in the internal workings of certain opto-electronic dev

Delaying light is sometimes used for a buffer in optical networks and signal processing, it is also used in the internal workings of certain opto-electronic devices such as optical oscillators; sometimes also used for testing and calibration of optical systems, making sure things are coming out as clean and at the same time as they do through the 'test' delay coil.