Light amplification from Cantor and asymmetric multilayer resonators.

The light amplification properties of fractal and asymmetric multilayer resonator structures which contain a light amplifying medium in the middle layer are studied theoretically. The amplitude gain of transmitted light is analyzed by use of two-dimensional plots which we denote gain maps. The gain map, which is plotted against two different structural parameters, illustrates some regularities in the location of gain peaks and bandgaps. Cantor structures exhibit gain peaks at the edges of multiple bandgaps, and those peaks are higher and sharper than those of periodic structures. Asymmetric resonator structures are found to provide more gain than symmetric ones when the gain length is short. A comparison between the gain and the group velocity of light is also presented, together with the electromagnetic energy distributions in the multilayers.