spontaneously move provided that a proper ratio of the carrier lifetimes in the amplifier and
in the absorber is considered. Use is made of this fact to propose a scheme based on which
a tunable all-optical delay line can be demonstrated. This easy-to-realize delay device
exhibits high delay range, a very good delay resolution, and a wide extent of available data
bandwidth. Also it is shown that the ratio of delay time to pulse duration (fractional delay) can …