We perform a near-field mapping of Bloch Surface Waves excited at the truncation interface of a planar silicon nitride multilayer. We directly determine the field distribution of Bloch Surface Waves along the propagation direction and normally to the surface. Furthermore, we present a direct measurement of a near-field enhancement effect under particular coupling conditions. Experimental evidence demonstrates that a approximately 10(2) near-field intensity enhancement can be realistically attained, thus confirming predictions from rigorous calculations.

We present results of numerical simulations and preliminary experiments to investigate and characterize the effect of asymmetrical coupling of normally incident light to surface plasmon polaritons ͑SPPs͒ on metallic blazed gratings. Two types of blazed gratings are investigated, a two-dimensional ͑2D͒ area-coded binary grating and a one-dimensional ͑1D͒ slanted sinusoidal grating. The 2D blazed grating, which can be fabricated with standard e-beam lithography, is shown to have the same ability as the classical 1D blazed grating to enhance the strength of the −1st͑+1st͒ evanescent order over the +1st͑−1st͒ counterpart, which leads to the asymmetrical excitation of two counterpropagating SPP modes on the grating surface. The 1D blazed grating, as a reference, is also studied experimentally to verify the previous theoretical predictions. In our first experiments, the observed asymmetrical coupling effect is relatively weak compared with the optimal designs due to many practical limitations. However, good agreement between theory and experiment has been obtained, and physical insight concerning the observed SPP coupling phenomena has been gained. Further measures to realize stronger asymmetrical excitation of SPPs on blazed gratings at normal incidence are discussed.

We have developed an approach for relatively rapid and easy fabrication of large-area two-dimensional (2-D) photonic crystal structures with controlled defects in the lattice. The technique is based on the combination of two lithographic steps in UV-sensitive SU-8 photoresist. First, multiple exposures of interference fringes are used in combination with precise rotation of the sample to define a 2-D lattice of holes. Second, a strongly focused UV laser beam is used to define line-defect waveguides by localized exposure in the recorded but not yet developed lattice from the first step. After development, the mask is transferred into a GaAs substrate with dry etching in chemically assisted ion-beam etching.

In this work, we use a multi-heterodyne scanning near-field optical microscope to investigate the polarization and propagation of Bloch surface waves in an ultrathin ͑ϳ /10͒ ridge waveguide. First, we show that the structure sustains three surface modes, and demonstrate selective excitation of each. Then, by numerically processing the experimental data, we retrieve the transverse and longitudinal components of each of the modes, in good agreement with the calculated fields. Finally, we provide an experimental estimation of the effective indices and the dispersion relations of the modes.

We present an extension of the rigorous coupled-wave analysis technique to analyze second-harmonic generation (SHG) in periodic optical nanostructures in the undepleted-pump approximation. We apply this method to analyze SHG in two example nanostructures for which we predict enhanced nonlinearity due to transverse near-field localization of the fundamental optical field in the nonlinear material. First, we examine a periodic nanostructure that yields up to twice the transmitted SHG intensity output compared with the bulk nonlinear material but only for small nanostructure depths because of mismatch of the fundamental and secondharmonic mode phase velocities. Second, we develop and analyze a modified nanostructure and find that this nanostructure concurrently achieves transverse localization and phase matching for SHG. In principle, this permits an arbitrary coherent interaction length, and for several specific nanostructure depths we predict a transmitted SHG intensity output more than two orders of magnitude greater than that of the bulk material.