Observation of "Frozen‐Phase" Propagation of THz Pulses in a Dispersive Optical System.

Dispersion occurs naturally in many wave systems. So far, a variety of techniques have been proposed and demonstrated to compensate the second‐order (group‐velocity) dispersion, such as dispersion management and nonlinear soliton formation, yet it is commonly believed that the first‐order dispersion (FOD) is less amenable and cannot be eliminated. In this work, it is shown that a phase‐invariant propagation of THz pulses, namely the "frozen‐phase" propagation, can be realized by a complete cancellation of the FOD, achieved by implementing a synchronized THz moving source with a locked initial phase. The dynamic generation and propagation process of the THz pulses is examined directly by a time‐resolved imaging system. To the best of authors' knowledge, this represents the first demonstration of the "frozen‐phase" propagation of a light pulse in dispersive optical systems. [ABSTRACT FROM AUTHOR]