Chalcogenide glass layers in silica photonic crystal fibers.

We report a novel approach for deposition of amorphous chalcogenide glass films inside the cylindrical air channels of photonic crystal fiber (PCF). In particular, we demonstrate the formation of nanocolloidal solution-based As(2)S(3) films inside the air channels of PCFs of different glass-solvent concentrations for two fibers with cladding-hole diameter 3.5 and 1.3 µm. Scanning electron microscopy is used to observe the formed chalcogenide layers and Raman scattering is employed to verify the existence and the structural features of the amorphous As(2)S(3) layers. Optical transmission measurements reveal strong photonic bandgaps over a range covering visible and near-infrared wavelengths. The transmittance spectra and the corresponding losses were recorded in the wavelength range 500-1750 nm. The main advantage of the proposed technique is the simplicity of the deposition of amorphous chalcogenide layers inside the holes of PCF and constitutes an efficient route to the development of fiber-based devices combined with sophisticated glasses for supercontinuum generation as well as other non-linear applications.

Label-free biosensing with high sensitivity in dual-core microstructured polymer optical fibers.

We present experimentally feasible designs of a dual-core microstructured polymer optical fiber (mPOF), which can act as a highly sensitive, label-free, and selective biosensor. An immobilized antigen sensing layer on the walls of the holes in the mPOF provides the ability to selectively capture antibody biomolecules. The change of the layer thickness of biomolecules can then be detected as a change in the coupling length between the two cores. We compare mPOF structures with 1, 2, and 3 air-holes between the solid cores and show that the sensitivity increases with increasing distance between the cores. Numerical calculations indicate a record sensitivity up to 20 nm/nm (defined as the shift in the resonance wavelength per nm biolayer) at visible wavelengths, where the mPOF has low loss.

Bending loss and thermo-optic effect of a hybrid PDMS/silica photonic crystal fiber.

In this paper, we demonstrate and report a photonic crystal fiber (PCF) infiltrated with PDMS elastomer which is sensitive to external bending and temperature perturbations. Numerical simulations and experimental measurements were carried out to investigate the fundamental TIR-based guiding mechanism of the hybrid PDMS/silica PCF in terms of effective index, effective modal area and loss. Wavelength dependence of bending losses was also measured for different bend diameters as well as the temperature dependence of the fundamental guiding mode for a range of temperatures from 20°C to 75°C. Experimental measurements have shown a ~6% power recovery of the bend-induced loss for a 6-cm long PDMS-filled PCF at 4 cm bend diameter.