We report in this Letter that when radiation is incident on a metal surface perforated with an array of ring-shaped subwavelength apertures, the phase difference between the propagating surface Bloch wave and the localized surface wave can be tailored by the geometrical parameters of the array so as to affect the shape of the transmission spectrum. Above the resonant frequency of the aperture, interference between the two kinds of surface waves leads to a minimum in the transmission spectrum, whereas below it, the interference leads to a maximum. We suggest that this feature provides flexibility in engineering surface-wave-based all-optical devices.

A fractal-featured metallic thin film with Sierpinski Carpet pattern is fabricated on silicon wafer by microfabrication techniques. Transmission infrared spectroscopy indicates that there exists extraordinary high transmission at specific wavelengths, which can be ascribed to the effect of surface plasmon resonance, and are determined by hierarchy of apertures of different sizes in the fractal structure. This patterned film provides a unique system to achieve enhanced transmission simultaneously at different selected frequencies of electromagnetic wave.

We show that transformation of glassy carbon (GC) into a translucent superhard carbon phase by cold-compression is obtained in the presence of a uniaxial stress field. This transition accompanies with sp² to sp³ bonding change in GC, and it is found that the uniaxial stress strongly favors this bonding transition. The transformation of GC causes photoluminescence and significantly increases light transmissivity. Upon decompression, the high pressure phase can be maintained under large uniaxial stress at a chamber pressure even down to ∼10 GPa. We discuss possible mechanisms of these transitions by a distinct bonding process that occurs in noncrystalline carbon.

Colloidal gold nanoparticles, extensively reagent-purified free and well size-controlled monodisperse, are chosen to study Surface Plasmon Resonance (SPR) under pressure with both in situ experimental measurements and theoretical calculations. The refractive index of water is enhanced by pressure up to 1.2 GPa, while the size, shape, and permittivity of gold nanoparticles change insignificantly. A redshift is shown in the absorption spectrum of gold nanoparticles during the process of increasing pressure and the absorption peaks corresponding to SPR of gold nanoparticles is found to be a linear dependence on the refractive index of water under pressure. It is very important to evaluate the wavelength of the absorption spectrum while we explore the phase transition of materials under pressure with surface enhanced Raman spectroscopy based on gold nanoparticles. These results provide us another method of tailoring SPR with pressure and enhancing the efficiency of detecting the weak optical signal under high pressure.