opals

Near-field probing of photonic crystals
E. Flück, M. Hammer, W. L. Vos, N. F. Van Hulst, and L. Kuipers
Photon. Nanostruct. Fundam. Appl. 2, 127-135 (2004)

Near-field optical investigation of three-dimensional photonic crystals
E. Flück, N. F. Van Hulst, W. L. Vos, and L. Kuipers
Phys. Rev. E 68, 015601(R):1-4 (2003)