Spectral, Temporal and Spatial Characteristics of Few Cycle Optical Pulsed Beam

Abstract

In this paper, the spectral, temporal and spatial properties of few cycle optical pulsed beam on propagation in free space has been studied. We analyze the spectral shifts of the ultrashort pulse in the far zone, and then discuss the scaling law of the pulsed sources. It is found that by the truncation of the pulsed beam, the scaling law may be destroyed. In this case the spectral shifts on propagation of the few cycle pulses may be observed in experiment. On the other hand, we reveal an analytical form of the pulsed Gaussian beam in free space and analyze the space-time coupling on propagation.

The techniques of ultrashort pulse laser have been developed rapidly. Up to date, pulses that are less than 5fs in duration and contain below two cycles can be generated [1]. The physics of the propogation of this extreme short pulse is important for the increasing number of application. In the many previous treatment, the electric fields of the pulse are always considered separable in space and time. But for few cycle optical pulses, its spatial and temporal characteristics interact with each other during propagation. On the other hand, since E.Wolf in 1986 [2] had revealed that light emitted a source which have a certain degree of spectral coherence and violate the called scaling law undergoes spectral shift during its propagation, this properties have been extensively studied for the partially coherent light. For few cycle optical pulse, its spectra is very broad. But how is the change of its spectra on propagation. What is the scaling law of this deterministic sources. In this paper, we will study these problems and discuss the spectral, temporal and spatical properties of few cycle optical pulsed beam on propagation.