The commonly used optical sensor based on surface plasmon-polariton wave phenomenon can sense just one chemical, because only one SPP wave can be guided by the interface of a metal and a dielectric material contained in the sensor. Multiple analytes could be detected and/or the sensing reliability for a single analyte could be enhanced, if multiple SPP-wave modes could be excited on a single metal/dielectric interface. For that to happen, the partnering dielectric material must be periodically non-homogeneous. Using a chiral sculptured thin film (CSTF) as that material in a SPP-wave platform, we show that the angular locations of multiple SPP-wave modes shift when the void regions of the CSTF are infiltrated with a fluid. The sensitivities realized in the proof-of-concept experiments are comparable to state-of-research values.

A form of physical vapor deposition, called the conformal-evaporated-film-by-rotation (CEFR) method, was optimized for the conformal deposition of columnar thin films (CTFs) on sebaceous fingermarks. Relying on the surface topology of the fingermark, the CTF development technique is different from traditional development techniques. After the optimization of the development conditions, the CTF development technique was found to be superior to traditional development methods on several nonporous substrates: the smooth side of Scotch(®) Multitask, Gorilla(®) , and Scotch(®) Duct tapes; clear and black soft plastics; stained and sealed walnut and cherry woods; partial bloody fingermarks on stainless steel; and discharged cartridge casings. It was equally as good as other development techniques on other substrates, but worse on a few. The optimization study is expected to assist in designing a mobile CEFR apparatus capable of on-scene development of fingermarks.

Blue iridescence is produced in the adaxial epidermal cell wall, which contains helicoid lamellae. The blue iridescence from cell surfaces is left-circularly polarized. The position of the silica granules is entrained by the helicoid microfibrillar layers, and granules accumulate at a uniform position within the helicoids, contributing to the structure that produces the blue iridescence, as part of the unit cell responsible for 2 ° Bragg scatter. Removal of silica from the walls eliminated the blue colour. Addition of silica nanoparticles on existing cellulosic lamellae is a novel mechanism for adding structural colour in organisms.

Abstract.A surface electromagnetic wave called the Dyakonov-Tamm wave has been theoretically predicted to exist at the interface of two dielectric materials at least one of which is both anisotropic and periodically nonhomogeneous. For experimental confirmation, a prism-coupled configuration was used to excite the Dyakonov-Tamm wave guided by the interface of a dense thin film of magnesium fluoride and a chiral sculptured thin film of zinc selenide. The excitation was indicated by a reflection dip (with respect to the angle of incidence in the prism-coupled configuration) that is independent of the polarization state of the incident light as well as the thicknesses of both partnering materials beyond some thresholds. Applications to optical sensing and long-range on-chip communication are expected.An electromagnetic surface wave propagates along the interface of two dissimilar materials. The fields of the surface wave must not only satisfy the Maxwell equations in both partnering materials, but must also decay far away from the interface [1,3,2]. The localization of the fields to the interface makes surface-wave propagation sensitive to changes in the electromagnetic properties of the partnering materials in the region near the interface [3,4]. Such changes alter the field distribution, the phase speed, and the attenuation rate of the surface wave and may even cause the surface wave to disappear entirely. This sensitivity is most often exploited for optical sensing applications [4,7,5,6], but surface waves also show potential for applications in microscopy, photovoltaics, and communication [8,9,10].Most of these applications have been realized for surface-plasmon-polariton (SPP) waves, which requires one of the two partnering materials to be a metal whereas the other one is a dielectric material. The concept of these surface waves excited at optical frequencies arose in 1957, when Ritchie [11] presented a plasma-oscillation explanation for energy losses of fast electrons traversing thin metal films. Simple optical methods to launch these surface waves emerged shortly thereafter [12,14,13].Metals dissipate optical energy; hence, most SPP waves do not propagate long distances along the interface plane [15]. The replacement of the partnering metal by a dielectric material different from the other partner should reduce attenuation rates and enhance propagation distances. Indeed, a second type of electromagnetic surface wave was predicted in 1977 to be guided by the interface of two isotropic dielectric materials, at least one of which was periodically non-homogeneous in the direction perpendicular to the interface [16]. This surface wave is often called a Tamm wave as it is analogous to the electronic states predicted to exist at the interface of two crystals by Tamm in 1932 [17]. The experimental observation of Tamm waves followed in 1978 [18] and, more recently, their application to sensing has been demonstrated as well [5,6,19]. A third type of electromagnetic surface wave was predicted by Dyakonov in 1988 to be...