We present the first experimental evidence for the existence of strongly localized photonic modes due to random two dimensional fluctuations in the dielectric constant. In one direction, the modes are trapped by ordered Bragg reflecting mirrors of a
planar, one wavelength long, microcavity. In the cavity plane, they are localized by disorder, which is due to randomness in the position, composition and sizes of quantum dots located in the anti-node of the cavity. We extend the theory of disorder induced strong localization of electron states to optical modes and obtain quantitative agreement with the main experimental observations.
