Light transport in random media with PT symmetry

The scattering properties of randomly layered optical media with PT-symmetric index of refraction are studied using the transfer-matrix method. We find that the transmittance decays exponentially as a function of the system size, with an enhanced rate xi(gamma)(W)(-1) = xi(0)(W)(-1) + xi(gamma)(0)(-1), where xi(gamma)(W) is the localization length of the equivalent passive random medium and xi(gamma)(0) is the attenuation and amplification length of the corresponding perfect system with a PT-symmetric refraction index profile. While transmittance processes are reciprocal to left-and right-incident waves, the reflectance is enhanced from one side and is inversely suppressed from the other, thus allowing such PT-symmetric random media to act as unidirectional coherent absorbers.