Light propagation in composite materials with gain layers

摘要: Light propagation through a single gain layer and multilayer system with layers is studied. Results obtained using the Fresnel formulas, Airy's series summation, numerical solution of nonlinear Maxwell-Bloch equations by finite difference time domain (FDTD) method are analyzed compared. Normal oblique wave slab photonic crystal examined. For latter problem, line may be situated in either pass or stop band crystal. It shown that monochromatic plane-wave approximation generally inapplicable for active media, because it leads to results violate causality. But problem becomes physically meaningful correct can all three approaches once structure wavefront aperture beam taken into account.