Observation of the Formation of an Optical Intensity Shock and Wave Breaking in the Nonlinear Propagation of Pulses in Optical Fibers

Abstract

A prominent class of phenomena in nonlinear wave propagation is that of shocks and breaking,1 which are known to occur in many diverse physical systems. Optical propagation in single mode fibers provides an excellent physical system for examining these phenomena because the propagation can be considered one dimensional, and is thought to be well described by the Nonlinear Schroedinger equation (NLSE). The possibility of so called optical intensity "envelope" shocks was first theoretically suggested by several researchers2-4 some 20 years ago. In the description of Ref. 3 a higher order nonlinear term was considered which results in an intensity dependent group velocity, but because they ignored the effects of dispersion, the shock formation proposed there has never been observed. Although, for optical pulses propagating in strongly nonlinear, dispersive near-resonant vapors, nsec observations of self-steepening have been reported.5 In addition, Hasegawa and Tappert6 have pointed out that the dark pulse solitary wave is in fact an example in the class of envelope shocks proposed by Ostrovskii.4