TY - JOUR T1 - Observation of Negative Refraction and Focusing in Two-Dimensional Photonic Crystals A1 - Ozbay, E. A1 - Bulu, I. A1 - Guven, K. A1 - Caglayan, H. A1 - Aydin, K. JA - Japanese J of Applied Physics Y1 - 2006 VL - 45 SP - 6064 EP - 6070 ER -