We present a direct evidence of Bloch surface waves (BSWs) waveguiding on ultrathin polymeric ridges, supported by near-field measurements. It is demonstrated that near-infrared BSWs sustained by a silicon-based multilayer can be locally coupled and guided through dielectric ridges of nanometric thickness with low propagation losses. Using a conventional prism-based configuration, we demonstrate a wavelength-selective BSW coupling inside and outside the ridge. Such a result can open interesting opportunities in surface wave-mediated sensing applications, where light could be selectively coupled in specific regions defined by nanometric reliefs.KEYWORDS Surface electromagnetic waves, near-field optical microscopy B loch surface waves (BSW) are either TE-or TMpolarized surface modes that can be sustained by truncated stacks of periodically arranged dielectric layers. 1,2 Although BSWs have been known for more than thirty years, they have been recently reconsidered as an alternative to surface plasmon polaritons (SPP), 3 in particular in sensing applications. [4][5][6] Until now, a number of far-field and near-field investigations have been conducted on the coupling of BSW on flat 7-9 and corrugated planar structures. [10][11][12] Here we demonstrate that near-infrared BSWs can be selectively prism-coupled and efficiently guided through an ultrathin polymeric ridge waveguide having thickness < λ/10 realized onto a silicon nitride multilayer. Besides being wavelength scalable and fully compatible with the actual fabrication technologies of integrated photonic and plasmonic structures, the proposed hybrid organic/inorganic structure can provide disruptive opportunities in waveguide-based biosensing schemes, (see, e.g., ref 13) in which the chemical specificity of the sensor might be implemented by functional molecule layers patterned as waveguides with nanometric thickness.In the past decade, a large number of issues connected to the guiding of electromagnetic surface waves (mostly SPP) on a subwavelength scale have been addressed by one branch of plasmonics. 14 Plasmonic waveguides according to different geometries have been proposed mainly for gaining strong (lateral) field confinement while maintaining low propagation losses in view of a high-density packing of integrated photonic circuitry. 15 In addition to guiding mechanisms based on ultrathin metallic membranes, 16 nanoparticles chains, 17,18 nanowires on dielectric substrates, 19 dielectric nanocylinders on metallic films, 20 or V-grooves in metal surfaces, 21 the most popular plasmonic waveguide configurations are constituted by metal-insulator-metal (MIM) 22,23 or insulator-metal-insulator (IMI) 24 structures. Among the latter, we recall the so-called dielectric-loaded surface plasmon polariton waveguides (DLSPPW), 25 in which a dielectric stripe is deposited onto a flat metallic film. The dielectric cladding is thick enough to confine SPP within the ridge, therefore lowering the propagation losses as well as the sensitivity upon external perturbat...

The effects on 4H-silicon carbide epilayers of irradiation with protons and electrons having particle energies, respectively, of 6.5 and 8.2MeV were carefully studied and critically compared. In detail, the electronic levels associated with the irradiation-induced defects were analyzed by current-voltage characteristics and deep-level transient spectroscopy (DLTS) measurements up to 550K. In the same temperature range the apparent free-carrier concentration was measured by capacitance-voltage characteristics in order to monitor compensation effects due to the deep levels associated with the induced defects. Introduction rate, enthalpy, and capture cross section of such deep levels were compared. We found that a set of deep levels (at ET=0.39eV, ET=0.65eV, and ET=0.75eV) is the same in both cases of proton and electron irradiations, whereas two other pairs of levels (S1, ET=0.20eV and S1*, ET=0.23eV; S5, ET=1.09eV and S5*, ET=0.89eV) appearing in the same temperature range within the DLTS spectra should be associated with different defect complexes according to the irradiation type. Some conclusions regarding the microscopic nature of the defects related to the deep levels have been drawn.

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An alternative route to plasmon-controlled fluorescence for improving the detection of fluorescence is proposed. In place of a metallic layer, a suitable silicon-based one-dimensional photonic crystal is used to generate a Bloch surface waves-coupled emission from a thin polymeric layer decorated with a fluorescent dye. Fluorescent radiation coupled to Bloch surface waves is strongly polarized and directional, with an angular divergence of 0.3° corresponding to a spectral bandwidth of 3 nm. Within this range, an overall signal enhancement of a factor larger than 500 is obtained as compared to a conventional glass substrate thanks to an additional enhancement mechanism based on dyes excitation via Bloch surface waves.

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.