Nano-Photonic Crystal D-Shaped Fiber Devices for Label-Free Biosensing at the Attomolar Limit of Detection.

Maintaining both high sensitivity and large figure of merit (FoM) is crucial in regard to the performance of optical devices, particularly when they are intended for use as biosensors with extremely low limit of detection (LoD). Here, a stack of nano-assembled layers in the form of 1D photonic crystal, deposited on D-shaped single-mode fibers, is created to meet these criteria, resulting in the generation of Bloch surface wave resonances. The increase in the contrast between high and low refractive index (RI) nano-layers, along with the reduction of losses, enables not only to achieve high sensitivity, but also a narrowed resonance bandwidth, leading to a significant enhancement in the FoM.

Bloch waves at the surface of a single-layer coating D-shaped photonic crystal fiber.

Bloch surface wave (BSW) platforms are particularly interesting for light confinement and surface sensitivity, as an alternative to the metal-based surface plasmon polaritons (SPP). However, most of the reported BSW platforms require depositing a large number of alternating dielectric layers to realize the excitation of the surface waves. In this Letter, we demonstrate an experimentally feasible D-shaped photonic crystal fiber (PCF) platform consisting of only a single dielectric layer on its flat surface, which can sustain Bloch waves at the boundary between the dielectric layer and the PCF cladding.

Bloch surface wave resonance in photonic crystal fibers: towards ultra-wide range refractive index sensors.

In this work, a new approach based on the use of a one-dimensional photonic crystal (1DPC) made of dielectric layers with alternating refractive indexes deposited inside a photonic crystal fiber (PCF) is proposed as a suitable platform for the excitation of Bloch surface waves (BSWs). The presence of an additional dielectric layer on the 1DPC modifies the local effective refractive index, enabling a direct manipulation of the BSWs. In particular, we investigate BSW resonance conditions in a 1DPC of alternating layers of TiO and SiO deposited inside a three-hole suspended-core PCF to design an ultra-wide range refractive index sensor in the near infrared.

Overview of remediation technologies for persistent toxic substances.

This paper gives a review of established and emerging technologies for the treatment of wastes and soils contaminated by Persistent Toxic Substances which include the Persistent Organic Pollutants. The technologies are classified as biological, physico-chemical, and thermal treatments, describing main unit operations and comparing technical, social and environmental limitations, including some potential risks and environmental impacts. Estimated overall costs, cleanup times, reliability, and maintenance levels are also presented in order to assess advantages and limitations of each technology.