Pulse propagation in nonlocal and nonlinear media

The linear reflection of a finite optical pulse from a semi-infinite non-local medium for various models of spatial dispersion (Additional Boundary Conditions: ABCs) is investigated theoretically. The effects of spatial dispersion for the reflected transients are important when the laser frequency is in the vicinity of an exciton-polariton resonance. For various ABC models, quantitative differences are found in the transient regime after the pulse dies out, and this can be used to analyze different ABCs experimentally.;The propagation of steady-state (solitary) pulses in local dielectric media is examined theoretically. Previous studies in the slowly varying envelope approximation (SVEA) in gases indicated that short pulses could propagate as solitons, giving rise to Self-Induced Transparency (SIT). By going beyond the SVEA to solve the Maxwell-Bloch equations, it is shown that polariton-soliton and SIT solutions do not exist except for solitary waves of special pulse widths, especially inside the polariton gap.