Propagation and interaction of ultrashort electromagnetic pulses in nonlinear media with a quadratic-cubic nonlinearity

摘要

Propagation of extremely short unipolar pulses of electromagnetic field("videopulses") is considered in the framework of a model in which the materialmedium is represented by anharmonic oscillators (approximating bound electrons)with quadratic and cubic nonlinearities. Two families of exact analyticalsolutions (with positive or negative polarity) are found for the movingsolitary pulses. Direct simulations demonstrate that the pulses are very robustagainst perturbations. Two unipolar pulses collide nearly elastically, whilecollisions between pulses with opposite polarities and a small relativevelocity are inelastic, leading to emission of radiation and generation of asmall-amplitude additional pulse.