  We demonstrate experimentally an efficient control of light intensity
distribution inside a random scattering system. The adaptive wavefront shaping
technique is applied to a silicon waveguide containing scattering
nanostructures, and the on-chip coupling scheme enables access to all input
spatial modes. By selectively coupling the incident light to open or closed
channels of the disordered system, we not only vary the total energy stored
inside the system by 7.4 times, but also change the energy density distribution
from an exponential decay to a linear decay and to a profile peaked near the
center. This work provides an on-chip platform for controlling light-matter
interactions in turbid media.
