Surface emitting laser based on random photonic crystals

Anderson localization (AL), the localization phenomenon of waves in random media, was theoretically predicted for electrons in a random potential in 1958 and still has been a recondite puzzle today. Stemming from interferences of multiply scattered waves, the principle is applicable to whole quantum as well as classical waves. Although experimental attempts toward AL of light had been performed in fully random structures such as aggregates of fine grains, it had been difficult to achieve because it demands materials with both extremely high scattering strength and low absorption losses. It was predicted in 1987 that localization may be more achievable in a randomized photonic crystal which supports a wide photonic band gap. However, AL of light is not yet experimentally exhibited except by far-field indirect observations in one- and two-dimensional structures. Here we show the first direct near-field observation of two-dimensional AL in random photonic crystal lasers by use of SNOM (Scanning Near-field Optical Microscope). We fabricated two-dimensional random photonic crystal lasers to which structural randomness is introduced by dislocating the positions of air holes to random directions. We show that only slight amount of randomness induces the extended Slow Bloch Modes to be Anderson localized, but too much randomness releases the light confinement. In addition, by performing FDTD computational method we confirm the experimental results to be consistent with theoretical prospects. Our results directly expose the detailed appearance of two-dimensional Anderson localized light first time ever.