While the absorption of light is ubiquitous in nature and in applications,
the question remains how absorption modifies the transmission channels in
random media. We present a numerical study on the effects of optical absorption
on the maximal transmission and minimal reflection channels in a
two-dimensional disordered waveguide. In the weak absorption regime, where the
system length is less than the diffusive absorption length, the maximal
transmission channel is dominated by diffusive transport and it is equivalent
to the minimal reflection channel. Its frequency bandwidth is determined by the
underlying quasimode width. However, when the absorption is strong, light
transport in the maximal transmission channel undergoes a sharp transition and
becomes ballistic-like transport. Its frequency bandwidth increases with
absorption, and the exact scaling varies with the sample's realization. The
minimal reflection channel becomes different from the maximal transmission
channel and becomes dominated by absorption. Counterintuitively, we observe in
some samples that the minimum reflection eigenvalue increases with absorption.
Our results show that strong absorption turns open channels in random media
from diffusive to ballistic-like.Comment: 11 pages, 7 figure
