Near-field optics with photonic crystals

Finite-difference time-domain (FDTD) analysis of light propagation in a defect made of a two-dimensional photonic band-gap (PBG) structure demonstrates that the light field is localized in such a structure within areas with subwavelength (lambda/10) sizes. FDTD simulations reveal efficient formation of an evanescent wave at the output of such a PEG structure, permitting the subwavelength resolution to be achieved in the near field. A probe object with a size less than the wavelength of incident light is shown to perturb the near-field distribution behind the PEG structure and to change the signal detected in the far-field zone. The field intensity distribution inside a PEG structure is also sensitive to the presence of a probe object, offering a way to control the light field localized in defect modes of PEG structures.