Abstract
In this work we present a new low cost SPR (Surface Plasmon Resonance) sensor configuration based on efficient higher-order mode filtering in plastic multimode fibers, using a tapered POF (Plastic Optical Fiber) after the sensor system, without decreasing the sensitivity of the sensor. In particular, we present the experimental results obtained with this new configuration. The experimental results have shown as the tapered POF after the sensor system influences the performances in terms of refractive index range and Signal-to-Noise Ratio (SNR).

Abstract
This paper investigates numerically the performance of a design for an optical sensor of the refractive index of gases and liquids based on smart or functional metamaterial films (smart optical metamembranes).

Abstract
The measurement of refractive index (RI) is an important tool for label free biosensing in biomedical applications [1,2]. In this work, a LPG based fiber optic interferometric probe is used for thrombin detection. The aptamer raised against the thrombin was immobilized through an electrostatic immobilization method, using poly-L-lysine as cationic polymer. The functionalized probe was characterized and tested against thrombin. The system was validated with the detection of thrombin using an aptamer based probe (5'-[ amine]GGTTGGTGTGGTTGG-3') as a model system for protein detection. The shift corresponding to the affinity-assay between TBA and the thrombin was of about 56 pm. A differential readout interferometer based on a white light Mach-Zehnder configuration, with pseudo-heterodyne phase modulation is described. The system can be used to interrogate two similar LPGs based interferometers in a differential scheme. Considering the configuration where both devices are functionalized being one active (sensor) and the other one passive ( reference) it is possible to accurately measure the behavior of the analyte of interest independent of non-specific binding events, bulk refractive index changes and temperature. Signal processing with low cost digital instrumentation developed in Labview environment allows a detectable change in refractive index of Delta n approximate to 2x10(6) [3]. Coupling the sensing probe together with a passively functionalized reference probe in a differential system will enable pseudo-heterodyne interrogation and extremely sensitive phase detection of biological species.

Abstract
Nafion has been evaluated as a sensing phase of an optical fibre humidity sensor based on a low-finesse Fabry-Perot interferometer. The sensor was constructed by manual deposition of a drop of a Nafion solution on the tip of a single mode optical fibre, forming a Fabry-Perot resonant cavity. The absorption of water by the Nafion film makes it swells, changing its refractive index and the length of the cavity, which produces a phase shift in the interference signal. The sensitivity, stability and response time of the sensor were evaluated in the RH range from 22 to 80% by analysing the correspondent reflection spectra of the interference fringes. As a result, it was obtained that Nafion can be used as sensing phase of an optical fibre humidity sensor based on optical fibre Fabry-Perot interferometry, presenting a response time of 242 ms (3% RH variation) and a sensitivity of 3.5 nm/%RH.

Abstract
We present a new method for coupling light to high-Q silica whispering gallery mode resonators (WGMs) that is based on long period fiber gratings (LPGs) written in silica fibers. An LPG allows selective excitation of high-order azimuthally symmetric cladding modes in a fiber. Coupling of these cladding modes to WGMs in silica resonators is possible when partial tapering of the fiber is also implemented in order to reduce the optical field size and increase its external evanescent portion. Importantly, the taper size is about one order of magnitude larger than that of a standard fiber taper coupler. The suggested approach is therefore much more robust and useful especially for practical applications. We demonstrate coupling to high-Q silica microspheres and microbubbles detecting the transmission dip at the fiber output when crossing a resonance. An additional feature of this approach is that by cascading LPGs with different periods, a wavelength selective addressing of different resonators along the same fiber is also possible. (C) 2014 Optical Society of America

Abstract
Traditionally, uorescence-based analytical methods were associated with high-cost bulky laboratory equipment. However, a diversity of technological advances taking place over the last 20 years concurred to change this picture. In the eld of optoelectronics, the advent of low-cost blue and UV lasers and LEDs, together with new miniature CCD spectrometers and high-sensitivity avalanche photodiodes (APDs), is enabling a new generation of spectroscopy tools to be developed and deployed in eld applications. On the other hand, chemistry and material sciences are delivering new types of uorescent materials with enhanced sensing properties, such as long-lived metallo-organic complexes or highly photostable quantum dots (QDs). Such developments are expanding the uses of uorescence and enabling new applications such as long-term multiwavelength imaging, ow cytometry analysis in microuidic chips, high-throughput DNA sequencing, and ber-optic-based diagnostic probes. © 2015 by Taylor and Francis Group, LLC.