We demonstrate the surface plasmon resonance (SPR)-enhanced angular Goos−Hanchen (GH) shift. Typical SPRenhanced GH shift measurements make use of loosely collimated beams, which enhances only the spatial GH shift (Δ GH ). Unlike this scheme, we focused the incident beam to a small beam waist to induce enhancement in the angular GH shift (Θ GH ). Although this makes Δ GH negligible, the enhancement of Θ GH is much larger than the decrease in Δ GH . In order to excite surface plasmons, we employ a Kretschmann configuration using a simple gold (Au) film on a substrate. We show that although the efficiency of surface plasmon excitation is decreased by the focused geometry, a significantly large Θ GH was induced. With the simultaneous measurement of reflectivity for SPR and the beam shift for the GH shift used in this work, we experimentally show the potential of measuring enhanced Θ GH toward sensing application when the Au film is exposed to local environmental changes even in the simplest thin film structure.

Pulsed laser deposition of BiSrCaCuO on MgO (100) using Q-switched Nd:YAG nanosecond laser operating at λ= 1064 nm (ns-PLD) and mode-locked Ti:Sa femtosecond laser at λ= 785 nm (fs-PLD) were performed. Rough surface with spheriodal morphology is the general microstructure of the deposited material from both nanosecond and femtosecond laser ablation. Femtosecond PLD resulted to granular morphology containing both BSCCO phase and rod-like Cu 2 O grains. Unlike ns-PLD, fs-PLD produced polycrystalline films even without heat treatment. These results indicate that two distinct ablation characteristic for ns-PLD and fs-PLD of BSCCO.

We demonstrate potential molecular monolayer detection using measurements of surface plasmon resonance (SPR) and angular Goos-Hänchen (GH) shift. Here, the molecular monolayer of interest is a benzenethiol self-assembled monolayer (BT-SAM) adsorbed on a gold (Au) substrate. Excitation of surface plasmons enhanced the GH shift which was dominated by angular GH shift because we focused the incident beam to a small beam waist making spatial GH shift negligible. For measurements in ambient, the presence of BT-SAM on a Au substrate induces hydrophobicity which decreases the likelihood of contamination on the surface allowing for molecular monolayer sensing. This is in contrast to the hydrophilic nature of a clean Au surface that is highly susceptible to contamination. Since our measurements were made in ambient, larger SPR angle than the expected value was measured due to the contamination in the Au substrate. In contrast, the SPR angle was smaller when BT-SAM coated the Au substrate due to the minimization of contaminants brought about by Au surface modification. Detection of the molecular monolayer acounts for the small change in the SPR angle from the expected value.