This paper describes a newly designed all-glass miniature (O 125 um) fiber-optic pressure sensor design that is appropriate for high-volume manufacturing. The fabrication process is based on the chemical etching of specially-designed silica optical fiber, and involves a low number of critical production operations. The presented sensor design can be used with either single-mode or multi-mode lead-in fiber and is compatible with various types of available signal processing techniques. A practical sensor sensitivity exceeding 1000 nm/bar was achieved experimentally, which makes this sensor suitable for low-pressure measurements. The sensor showed high mechanical stability, good quality of optical surfaces, and very high tolerance to pressure overload. This paper is summary of work that lead to world's smallest commercially available optical fiber pressure sensor.
COBISS.SI-ID: 13269526
This paper presents a high-sensitivity, all-silica, all-fiber Fabry- Perot strain-sensor. The proposed sensor provides a long active length, arbitrary length of Fabry-Perot cavity, and low intrinsic temperature sensitivity. The sensor was micro-machined from purposely-developed sensor-forming fiber that is etched and directly spliced to the lead-in fiber. This manufacturing process has good potential for cost-effective, high volume production. Its measurement range of over 3000 µ?, and strain resolution better than 1 µ? were demonstrated by the application of a commercial, multimode fiber-based signal processor. This paper presents strain a new way of deigning and producing highly effect FP strain sensors. Presented approach offers variety of possibilities for further development, as for example ways to achieve very high strain sensitivity (in nano-strain region) or building effect pressure sensors
COBISS.SI-ID: 15204118
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 temperature’s effect on the fluid’s refractive index change and consequently provides opportunities for the detection of very small changes in the surrounding fluid’s composition. A measurement resolution of 2x10^-7 RIU was demonstrated experimentally for a component of the refractive index that is related purely to the fluid’s 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 sensor’s optical spectrum. Paper presents two-parameter optical sensor for high resolution refractive index and temperature measurements, which can be used for detection of very small changes in fluid's composition through RI sensing. Paper demonstrated record-high, temperature-independent RI measurement resolution of 2x10-7 RIU .
COBISS.SI-ID: 17928982
This paper presents a maskless micromachining process that can reform or reshape a section of an optical fiber into a complex 3-D photonic microstructure. This proposed micromachining process is based on the etching rate control achieved by the introduction of phosphorus pentoxide into silica glass through standard fiber manufacturing technology. Regions within a fiber cross section doped with phosphorus pentoxide can etch up to 100 times faster than pure silica when exposed to hydrofluoric acid. Various new photonic devices can be effectively and economically created by design and production of purposely doped fibers that are spliced at the tip or in-between standard lead-in fibers, followed by etching into a final structure. Paper presents cost-efficient micromachining technology based on selective etching of phosphorus doped optical fiber. Almost all original fiber structures presented in the research program are based on this technology. This technology allows for completely new approach in reshaping and reforming of optical fibers in complex microstrctures.
COBISS.SI-ID: 15204374
This paper presents a method for the efficient production of all-fiber semi reflective mirrors suitable for fiber sensors and other all-fiber device applications. The mirrors are obtained by the short duration etching of a standard single mode fiber in hydrofluoric acid, followed by an on-line feedback-assisted fusion splicing process. Fiber mirror reflectance up to 9.5%with excess losses below 0.25 dB were produced in practice, which is in good agreement with provided theoretical and modeling analyses. Control over the etching time and fusion splicing process allows for balancing between reflectance and transmittance, while maintaining low excess loss of experimentally produced mirrors. Paper presents a method for production of in-fiber mirrors, which are fundamentals for in-fiber Fabry-Perot sensors, multi-parameter Fabry-Perot sensors, filters and other optical fiber devices.
COBISS.SI-ID: 14128662
This Letter presents a method for the fast and broad wavelength sweeping of a standard setup of a diode's active region and its immediate vicinity, which contain the diode's optical feedback system. The selective and rapid heating of the active region is possible due to the confinement of the voltage drop to the active diode's region that has submicrometer thickness. Using the presented method and an off-the-shelf telecommunication distributed feedback laser diode, we demonstrate wavelength sweeps in excess of 10 nm that were completed in about 200 ns, while generating average optical power in excess of 50 mW. In spite of high-amplitude current-drive pulses, 6000 h continuous operation of the diode within such an operational regime did not show any significant degradation of the diode's performance. Papers presents method for driving standard telecommunication laser diode in a way to induce very large wavelength sweep and allows the use of a standard DFB diode as an tunable laser source. This method is base for further developement of interrogation systems.
COBISS.SI-ID: 16918806
An efficient fiber Bragg grating (FBG) sensor integration system, which utilizes a small number of standard Telecom opto-electronics components, is presented in this paper. Wavelength-swept optical pulses were generated by driving a standard telecom DFB laser diode by high amplitude ()3 A) and short duration (300 ns) current pulses. A total laser diode's wavelength sweep in excess of 10 nm was achieved, which allows for simultaneous interrogation of several FBGs within similar wavelengths. The application of short duration wavelength-swept optical pulses also allows for time division multiplexing of small FBG arrays containing FBGs with overlapping characteristic wavelengths. When a short, wavelength-swept optical pulse is launched into the fiber containing single or multiple FBGs along its length, fractions of the launched pulse are back-reflected towards the detector. Since the launched pulse wavelength changes over the time, the reflections from the FBGs occur in the time moments that depend on the FBGs' characteristic wavelengths. Measurement of the time delay among back-reflected optical pulses is then used to determine the FBGs characteristic wavelengths. The experimental system demonstrated FBG wavelength readout resolution, which exceeded 3 pm at 1 KHz sampling rate, maximum sampling rate of over 40 KHz, and capability to readout/demultiplex over 30 FBGs located down a single optical fiber. Paper presents original concept of a cost-efficient fiber Bragg grating interrogation system. The system consist of small number of simple and cost efficient components and can serve as base suitable for deign of a broad range of industrial systems.
COBISS.SI-ID: 20016918
This paper presents a miniature, all-optical, thermal conductivity fiber-optic sensor, which can be applied to various fluid composition identification situations. The sensor is composed of a short section of highly absorbing fiber, which is configured as a Fabry-Perot interferometer. A higher power laser diode is used to heat the absorbing fiber periodically, while proper signal integration system issued in order to observe temperature variations of the heated fiber. These variations are further correlated to the surrounding fluid’s thermal conductivity. The sensor was applied experimentally to various fluid identification situations, including gas/liquid and liquid–liquid phase detection, identification of different fluids (including liquids and gases), liquids’ binary mixtures mass ratio determination, and some common fluid identification applications. Paper presents a new possible approach in all-optical chemical sensing. New generation of robust all-optical sensor system for fluid’s composition characterization are possible by using proposed approach.
COBISS.SI-ID: 20017174
This letter presents an optical fiber twist/torsion sensor that utilizes dissimilar polarization-preserving characteristics of standard single-mode and high-birefringence fibers. When only one polarization mode of the high-birefringence fiber is excited, spatial orientation of the E-field vector follows the fiber’s principal axis orientation, even when the fiber is twisted around its longitudinal axis. This is contrary to a standard single-mode fiber (SMF), where the E-field vector maintains its spatial orientation regardless of the fiber torsional twist. The proposed sensor consists of a short section of standard SMF inserted in between two lead-in polarization-mainlining fibers. Only one mode of the lead-in fiber is excited at the input, while the ratio of both polarization modes is measured at the output side of the fiber assembly in order to determine the torsional twist of a standard SMF. This sensor can be used for measuring unambiguously twist/torsion angles of between ±95°. The sensor demonstrated very low temperature dependence. Letter presents a twist/torsion sensor based on measurements of E-field displacement, which opens new directions in rotation sensing.
COBISS.SI-ID: 16877590
Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation. This paper presents first review in literature on fiber-optic sensors for torsion, twist and rotation measurements.
COBISS.SI-ID: 20282902