The reflection and transmission characteristics of a high-birefringence fiber loop mirror (HiBi-FLM), which is composed of a standard fiber coupler and one-section or multisection high-birefringence fibers (HBFs), are analyzed and discussed in detail. Theoretical reflectivity and transmissivity expressions for HiBi-FLMs with one-, two-, and three-section HBFs were obtained. The procedure for calculating reflectivity and transmissivity for HiBi-FLMs with n-section HBFs is given. Experimental results have verified the theoretical model. The basic characteristics of the one-section HiBi-FLM when strain and high temperature are applied to HBFs were analyzed and investigated theoretically and experimentally. The experimental results are in good agreement with the theoretical analysis. Furthermore, a strain– temperature sensor that makes use of those characteristics, which is new for applications of HiBi-FLMs, has been proposed and demonstrated.

High-birefringence fiber loop mirrors and their applications as sensors.

A compact temperature sensor based on a fiber loop mirror (FLM) combined with an alcohol-filled high-birefringence photonic crystal fiber (PCF) is proposed and experimentally demonstrated. The output of the FLM is an interference spectrum with many resonant dips, of which the wavelengths are quite sensitive to the change of the refractive index of the filled alcohol for the interference of the FLM. Simulation analysis predicts a high temperature sensitivity, and experimental results show it reaches up to 6.6 nm/°C for the 6.1-cm-long PCF used in the FLM.

High-sensitivity temperature sensor based on an alcohol-filled photonic crystal fiber loop mirror

Inertial Navigation Systems have found universal application both militarily and commercially. They are self-contained, nonradiating, nonjammable, and sufficiently accurate to meet the requirements of users in a most satisfactory manner. An overview of inertial navigation is provided, followed by several sections detailing a specific, but different mechanization approach. A Ring Laser Gyro (RLG) based navigation system design is reviewed with special emphasis directed at requirements for navigation accuracy and alignment time. Along with discussions of the RLG unit, an introduction to a novel accelerometer approach, the Vibration Beam Accelerometer (VBA), is provided. A gimballed, self-contained High Accuracy Inertial Navigation System, denoted HAINS, represents one approach toward achieving navigation capability of 0.2 nmi / h and an rms velocity of 1.5 ft / s per axis while retaining the form and fit and affordability of standard inertial tactical flight navigators. The Stellar-Inertial Navigation section illustrates the bounding of position and verticality errors thus achieving exceptional accuracies. Two gyroscopic approaches, presently in development are finally discussed. The Fiber Optic Gyroscope (FOG) and Magnetic Resonance Gyroscopes (MRG's) are of interest for navigation because of their potential for low cost and excellent reliability.

Inertial navigation

The use of broad-band sources, polarized and unpolarized, in fiber gyroscopes with linearly birefringent fibers, is studied theoretically. Polarization-mode coupling in the fiber is modeled using one-mode coupling center. Gyroscope output equations are obtained which are useful in interpreting an origin of fiber noise in the limiting cases of low and high fiber birefringence. Interference effects in the output are shown to be related to mode coupling at particular locations in the fiber. The extent of these locations is governed by a depolarization length for which numerical estimates are given.

Fiber-optic gyroscopes with broad-band sources

The invention relates to a set of combinatorially labeled oligonucleotide probes each member thereof: (i) having a predetermined label distinguishable from the label of any other member of said set, and (ii) being capable of specifically hybridizing with a predetermined chromosome or nucleic acid molecule, and to the use of such molecules, alone or in concert with nucleic acid amplification methods.

Multiparametric fluorescence in situ hybridization

A formalism is presented for treating birefringence and polarization in fiber optic sensors. This formalism is applied to study theoretical characteristics of fiber gyroscopes which are operated with various states of polarization of the input light including nonpolarized and partially polarized light, which have potentially useful characteristics. Measurements supporting the theoretical predictions are described.

Birefringence and polarization effects in fiber gyroscopes

Un detecteur rotatif a fibre optique, utilisant la detection du dephasage de Sagnac, comprend une fibre a simple mode (11) formant une boucle (16). A fiber optic rotary detector, using detection of the Sagnac phase shift, comprises a single mode fiber (11) forming a loop (16). Le detecteur rotatif utilise la lumiere non polarisee pour produire un fonctionnement alternatif. The rotary detector uses unpolarized light to produce an alternative operation. La lumiere non polarisee produit des composantes d'onde de lumiere incoherentes dont la moyenne sur zero est effectuee dans le detecteur (20). Unpolarized light produces incoherent light wave components whose zero on average is calculated in the detector (20). Des dephasages induits de maniere non rotative entre des composantes d'onde de lumiere coherentes se traduisent en vecteurs (54(a), 54(b)) egaux en intensite et d'angles de phases opposes de sorte que les composantes non alternatives de ces vecteurs s'annulent. Induced phase shifts nonrotatably between coherent light wave components translate into vectors (54 (a), 54 (b)) equal in intensity and opposite phase angles so that non AC components of these vectors cancel. Le detecteur rotatif est independant des facteurs de l'environnement lorsque la difference de phase entre les ondes se propageant a contre-courant au travers de la boucle (16) est un multiple impair de pi/2. The rotary detector is independent of environmental factors when the phase difference between the waves propagating against the current through the loop (16) is an odd multiple of pi / 2. Par consequent, le detecteur comprend un dephaseur (17) pour polariser une telle difference de phase sur pi/2 de maniere a obtenir un point de fonctionnement stable lorsque la boucle est au repos. Therefore, the detector comprises a phase shifter (17) for biasing such a phase difference of pi / 2 so as to obtain a stable point of operation when the loop is at rest. De plus, des moyens de compensation (70, 78, 82) sont prevus pour assurer une stabilite pendant la rotation. In addition, compensation means (70, 78, 82) are provided to ensure stability during rotation.

Fiber optic rotation sensor utilizing unpolarized light

A fiber optic rotation sensor utilizes multimode optical fiber to improve power coupling and reduce coherent back scattering. A multimode light source such as a light emitting diode can be used. The system is economical and environmentally stable.

Pavlath George A

Papers

Birefringence and polarization effects in fiber gyroscopes

Fiber optic rotation sensor utilizing unpolarized light

Multimode fiber optic rotation sensor.