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High resolution, all-fiber, micro-machined sensor for simultaneous measurement of refractive index and temperature

This paper presents a highly-sensitive, miniature, all-silica, dual parameter fiber-optic Fabry-Perot sensor, which is suitable for independent measurement of the refractive index and the temperature of the fluid surrounding the sensor. The experimental sensor was produced by a micromachining process based on the selective etching of doped silica glass and a simple assembly procedure that included fiber cleaving, splicing and etching of optical fibers. The presented sensor also allows for direct compensation of the temperatures effect on the fluids refractive index change and consequently provides opportunities for the detection of very small changes in the surrounding fluids composition. A measurement resolution of 2x10-7 RIU was demonstrated experimentally for a component of the refractive index that is related purely to the fluids composition. This resolution was achieved under non-stabilized temperature conditions. The temperature resolution of the sensor proved to be about 10-3 C. These high resolution measurements were obtained by phase-tracking of characteristic components in a Fourier transform of sensors optical spectrum.

Miniature all-fiber FabryPerot sensor for simultaneous measurement of pressure and temperature

This article presents a miniature, high-sensitivity, all-silica FabryPerot fiber-optic sensor suitable for simultaneous measurements of pressure and temperature. The proposed sensor diameter does not exceed 125 ?m and consists of two low-finesse FabryPerot resonators created at the tip of an optical fiber. The first resonator is embodied in the form of a short air cavity positioned at the tip of the fiber. This resonator utilizes a thin silica diaphragm to achieve the sensors pressure response. The second resonator exploits the refractive index dependence of silica fiber in order to provide the proposed sensors temperature measurement function. Both resonators have substantially different lengths that permit straightforward spectrally resolved signal processing and unambiguous determination of the applied pressure and temperature.

Micromachining of all-fiber photonic micro- structures for microfluidic applications

Maskless micromachining of all-fiber photonics structures, based on the selective etching of structure forming optical fibers (SFF) is presented. A maskless micromachining process can reform or reshape a section of an optical fiber into a complex 3D photonic microstructure. This proposed micromachining process is based on the introduction of phosphorus pentoxide (P2O5) into silica glass through standard fiber manufacturing technology. Micro-machining is presented as a highly effective tool for the realization of new solutions in the design of optical sensors and microfluidic devices.

Multiparameter fiber-optic sensor for simultaneous measurement of thermal conductivity, pressure, refractive index, and temperature

This paper presents a miniature, all-silica four/multiparameter sensor for simultaneous measurements of thermal conductivity, pressure, refractive index, and temperature of gases. The sensor is composed of multiple Fabry-Perot interferometers (FPIs) that were created at the tip of a standard optical fiber by a micromachining process based on selective etching and standard fiber manipulation steps. The experimental sensor length was below 3.4 mm, while the diameter did not exceed 125 ?m. Interrogation of the sensor utilized acquisition and appropriate signal processing of the back-reflected optical spectrum, which allowed for crosstalk free extraction of individual resonators' lengths. High repeatability and resolutions were demonstrated for all four sensed parameters. The sensor might be applied to a variety of problems related to gas monitoring or composition analyze as, for example, binary, or even trinary gas mixtures.