  We study theoretically light focusing at subwavelength scale inside a
disordered strongly scattering open medium. We show that broadband time
reversal at a single point antenna, in conjunction with near-field interactions
and multiple scattering, produces spatial focusing with a quality comparable to
that obtained in an ideal closed cavity. This gives new perspectives for
super-resolved optical imaging and coherent control of single nanosources or
absorbers in complex media.
