Photoinduced electron transfer based ion sensing within an optical fiber.

We combine suspended-core microstructured optical fibers with the photoinduced electron transfer (PET) effect to demonstrate a new type of fluorescent optical fiber-dip sensing platform for small volume ion detection. A sensor design based on a simple model PET-fluoroionophore system and small core microstructured optical fiber capable of detecting sodium ions is demonstrated. The performance of the dip sensor operating in a high sodium concentration regime (925 ppm Na(+)) and for lower sodium concentration environments (18.4 ppm Na(+)) is explored and future approaches to improving the sensor's signal stability, sensitivity and selectivity are discussed.

Index matching between passive and active tellurite glasses for use in microstructured fiber lasers: erbium doped lanthanum-tellurite glass.

Active and passive variants of La-containing tellurite glasses have been developed with matched refractive indices. The consequences of adding lanthanum to the glass was studied through measurements of the crystallization stability, glass viscosity and the loss of unstructured fibers. Doping the glass with erbium allowed for any spectroscopic changes to be observed through measurements of the absorption and energy level lifetimes. The fluorescence emission spectra were measured at 1.5 microm and, to the best of our knowledge, for the first time in tellurite glass at 2.7 microm.

Exposed-core microstructured optical fibers for real-time fluorescence sensing.

New methods for fabricating glass exposed-core microstructured optical fiber are demonstrated. The fiber designs consist of an optical fiber with a suspended micron-scale core that is partially exposed to the external environment, which is particularly useful for sensing. These fibers allow for strong evanescent field interactions with the surrounding media due to the small core size, while also providing the potential for real-time and distributed measurements. The experimental performance of an exposed-core fiber is compared to an equivalent microstructured fiber with an enclosed (protected) core in terms of their performance as evanescent field sensors. We demonstrate that the exposed-core fiber can provide a significantly improved measurement response time.

Fluoride glass microstructured optical fiber with large mode area and mid-infrared transmission.

We demonstrate the first fluorozirconate microstructured fiber for use in the mid-infrared. The fiber preform was manufactured via extrusion of a 200 g billet through a complex graphite die. The fiber exhibits large mode area of 6,600 microm(2), loss of 3 dB/m at 4 microm and only marginal excess loss relative to a corresponding unstructured fiber.

Antibody immobilization within glass microstructured fibers: a route to sensitive and selective biosensors.

Glass microstructured optical fibers have been rendered biologically active for the first time via the immobilization of antibodies within the holes in the fiber cross-section. This has been done by introducing coating layers to the internal surfaces of soft glass fibers. The detection of proteins that bind to these antibodies has been demonstrated experimentally within this system via the use of fluorescence labeling. The approach combines the sensitivity resulting from the long interaction lengths of filled fibers with the selectivity provided by the use of antibodies.