Search results for "Fiber Optic"
showing 10 items of 193 documents
<title>Control and measuring buses with amplitude fiber optical sensors</title>
2004
This paper presents controlling-measuring buses (linear and quasi-linear) using amplitude properties of fiber-optics and fiber-optical sensors of typical and/or special construction. It refers to linear sensors and commonly used measuring OTDR method, as wel as to realizations with linear binary sensors in transmission networks. Presented advantages and parameters of such measuring structures. Presented main area of application buses and practical realizations, regarding typical needs in industrial measurements, points out technical and economical advantages, in opposition to difficult and expensive (but more accurate) technology of measuring networks based on polarization and interfering m…
<title>Fiber optic monitoring buses with binary on-off sensors</title>
1999
This paper presents general theoretical considerations of complex-structure optical fiber networks (buses) with binary `on-off' fiber optic sensors and fiber optic transmission lines for monitoring, diagnostic or measurement systems. The principles of fiber optic serial and parallel buses and various types of intensity fiber optic binary sensors are described as well as the advantages and disadvantages of the individual types of networks. The choice of the use of fiber optic technology rather than other techniques is discussed. Special emphasis was put on the role and function of optoelectronic and optical fiber devices in harsh environments. Theoretical considerations are illustrated by th…
A Non-Invasive Thermal Drift Compensation Technique Applied to a Spin-Valve Magnetoresistive Current Sensor
2011
A compensation method for the sensitivity drift of a magnetoresistive (MR) Wheatstone bridge current sensor is proposed. The technique was carried out by placing a ruthenium temperature sensor and the MR sensor to be compensated inside a generalized impedance converter circuit (GIC). No internal modification of the sensor bridge arms is required so that the circuit is capable of compensating practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a microfabricated spin-valve MR current sensor. The temperature compensati…
Label-free wavelength and phase detection based SMS fiber immunosensors optimized with cladding etching
2018
The performance of E-SMS (Etched Singlemode-Multimode-Singlemode) optical fiber structures as immunosensors has been assessed by the implementation of antibody/antigen immunoassays. Through this procedure it has been proven that E-SMS structures are effective and suitable optical platforms for label-free biosensing. Using the phase shift and tracking the wavelength response it was found that the fabricated E-SMS devices exhibited limits of detection (LOD) down up to concentrations of 0.2mg/L of antigens in solution. This was achieved by coating the E-SMS with an antibody-based biolayer (goat IgG) that is able to determine the presence of anti-goat IgG antigen. Both a wavelength detection an…
Transvalvular enteroscopy using a mother-baby endoscope system: a new approach to the distal ileum.
1997
In the past decade various endoscopes have been developed to examine the small bowel, with two principal procedures established: sonde-type enteroscopy and push-type enteroscopy. The main indication is gastrointestinal bleeding of obscure origin. Push-type enteroscopy has proved itselfto be useful for the investigation ofdiseases of the small intestine. 1 The mean instrumental insertion length published by different working groups varied between 50 and 90 cm past the ligament of Trei tzfl 2 The small bowel examination area is limited to the jejunum. The alternative method is sonde-type enteroscopy that allows an insertion length of 140 (30 to 200) cm. 3, 4 Disadvantages of this type of ente…
In-line fiber-optic sensors based on the excitation of surface plasma modes in metal-coated tapered fibers
2001
Abstract Metal-coated tapered fibers are reported as refractive index sensors based on the resonant excitation of surface plasma modes supported by the metal coating. The devices are easy to fabricate and constitute an alternative to metal-coated side-polished fibers and to other sensors made up of bulk components. We report the fabrication and power transmission properties of quasi-circular devices and asymmetric devices. Both sets of devices can be operated as wavelength output sensors, as well as amplitude output sensors. The transmittance of quasi-circular devices is polarization independent and it changes more than 30 dB as a function of external refractive index.
Integrated optic Surface Plasmon Resonance Measurements in Glass substrates
2007
The surface plasmon resonance (SPR) technique is an optical method that can be used to measure the refractive index of organic nano-layers adsorbed on a thin metal film. Although there are many techniques for measuring biomolecular interactions, SPR-based techniques play a central role in many current biosensing experiments, since they are most suited to sensitive and quantitative kinetic measurements. Here we give some results from the analysis and numerical elaboration of SPR data regarding the flow of different solutions with refractive indexes in the range of interest (1-1.4). After a brief discussion of the principles of SPR and of waveguide fabrication technique, we give a description…
Formation of ultrashort triangular pulses in optical fibers
2014
Specialty shape ultrashort optical pulses, and triangular pulses in particular, are of great interest in optical signal processing. Compact fiber-based techniques for producing the special pulse waveforms from Gaussian or secant pulses delivered by modern ultrafast lasers are in demand in telecommunications. Using the nonlinear Schr¨odinger equation in an extended form the transformation of ultrashort pulses in a fiber towards triangular shape is characterized by the misfit parameter under variety of incident pulse shapes, energies, and chirps. It is shown that short (1-2 m) conventional single mode fiber can be used for triangular pulse formation in the steady-state regime without any pre-…
Impact of initial pulse shape on the nonlinear spectral compression in optical fibre
2018
International audience; We theoretically study the effects of the temporal intensity profile of the initial pulse on the nonlinear spectral compression process arising from nonlinear propagation in an optical fibre. Various linearly chirped input pulse profiles are considered, and their dynamics is explained with the aid of time-frequency representations. While initially parabolic-shaped pulses show enhanced spectral compression compared to Gaussian pulses, no significant spectral narrowing occurs when initially super-Gaussian pulses are used. Triangular pulses lead to a spectral interference phenomenon similar to the Fresnel bi-prism experiment.
Femtosecond parabolic pulse shaping in normally dispersive optical fibers
2013
Formation of parabolic pulses at femtosecond time scale by means of passive nonlinear reshaping in normally dispersive optical fibers is analyzed. Two approaches are examined and compared: the parabolic waveform formation in transient propagation regime and parabolic waveform formation in the steady-state propagation regime. It is found that both approaches could produce parabolic pulses as short as few hundred femtoseconds applying commercially available fibers, specially designed all-normal dispersion photonic crystal fiber and modern femtosecond lasers for pumping. The ranges of parameters providing parabolic pulse formation at the femtosecond time scale are found depending on the initia…