Optical Delay Lines Based on Optical Filters

Optical delay lines have some important applications, notably in optical communication systems and in phase arrays. These devices fare based on the concept of optical group delay, which, in turn, can be understood as the property of an optical filter. Optical filters are well-understood devices and in particular their dispersive properties determine the group delay response. We review these dispersive properties and point out some of the inherent tradeoffs involved in generating large group delay. Fiber Bragg gratings and recent results on optical all-pass filters, are used as examples.