LIGHT AMPLIFICATION AND LOCALIZATION IN RANDOMLY LAYERED MEDIA WITH GAIN

Light amplification and localization behaviors in randomly layered media with gain are studied using the transfer-matrix method. It is found that localization is enhanced due to the amplification of coherent backscattering effect. It is also found that xi(O) and l(g) are the only two relevant parameters in such systems, where xi(O) is the localization length in the absence of gain and l(g) is the gain length. The interplay of xi(O) and l(g) gives rise to two new lengths L(sr) and xi. L(sr), which behaves like (l(g) xi(O))(0.5), is a manifestation of the threshold length for the super radiation, which is strongly suppressed in one dimension. xi is the localization length in the presence of gain, which can be described by 1/xi = 1/xi(O) + 1/l(g). Results for dissipative media are also presented.