Senzorji lomnega količnika
Nanowire-based refractive index sensor on the tip of an optical fiber

This letter presents a refractive index sensor created at the tip of an optical fiber that utilizes silica nanowire within a radius of between 225?nm and 600?nm, as a sensing element. Sensitivity in excess of 800?nm/RIU was demonstrated within an aquatic medium, while the entire sensor structure was shorter than 1?mm with a diameter equal to or less than the standard fiber diameter. The presented sensor structure is made entirely from silica and provides the mechanical protection of sensitive nanowire. The proposed sensor is thus a robust and self-sustained structure, which does not require any complex packing.

In-Line FabryProt Refractive Index Sensor

An in-line intrinsic FabryProt refractive index (RI) sensor is demonstrated. The sensor consists of a short single-mode fiber (SMF) section with removed cladding that is fusion spliced between two lead fibers containing in-fiber mirrors. The measured medium surrounding the decladed fiber section affects the fundamental modes effective index and, consequently, the optical path length of the FabryProt interferometer (FPI). Sensors with different diameters of decladed regions were produced and experimentally evaluated within an RI range of between 1.33 and 1.444. The proposed sensor can be interrogated by standard spectrally resolved interrogators.

All-fiber micromachined microcell

This Letter presents an open-path, all-fiber microcell and a micromachining method for its production. The proposed micromachining method utilizes the selective etching of a purposely designed phosphorus-doped fiber that is spliced in between two standard lead-in fibers. Microcells with various open optical-path lengths were successfully demonstrated. The proposed microcell can be used as a transmission cell or as a miniature FabryPerot resonator. The transmission losses and fringe contrast were experimentally investigated over a range of prototype microcells with different lengths. For example, the insertion losses below 1 dB were demonstrated for 50 ?m or shorter open path prototype microcells, when immersed in dematerialized water.

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.