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Limitations on High Data Rate Optical Fiber Transmission Systems Due to Transmission Impairment

Description: This project supplemented our regular DOE grant from the Basic Energy Sciences organization with the goal of fostering industrial partnerships and student internships. During the project period, we have interacted with between 15 and 20 companies in the optical fiber telecommunications equipment industry, and our students have participated in a number of highly visible projects with companies such as Ciena, Science Applications International Corporation, KDD, ATT, Virtual Photonics, Inc., Phaethon Telecommunications, PhotonEx, and others. The project led to many successful interactions and numerous job offers for our students.
Date: March 15, 2002
Creator: Menyuk, Curtis R.
Partner: UNT Libraries Government Documents Department

SBIR Final Report. Liquid Core Optical Scintillating Fibers

Description: This Phase I SBIR project focused on developing flexible scintillating liquid core optical fibers, with potential uses in high-energy calorimetry, tracking, preradiators, active targets or other fast detectors. Progress on the six tasks of the project is summarized. The technical developments involve three technology components: (1) highly flexible capillaries or tubes of relatively low n (index of refraction) to serve as cladding and liquid core containment; (2) scintillator (and clear) fluids of relatively high n to serve as a core-- these fluids must have a high light transmission and, for some applications, radiation hardness; (3) optical end plugs, plug insertion, and plug-cladding tube sealing technology to contain the core fluids in the tubes, and to transmit the light.
Date: May 16, 2000
Creator: Beetz, C.P.; Steinbeck, J. & Buerstler, R.
Partner: UNT Libraries Government Documents Department

Fabricating Optical Fiber Imaging Sensors Using Inkjet Printing Technology: a pH Sensor Proof-of-Concept

Description: We demonstrate the feasibility of using Drop-on-Demand microjet printing technology for fabricating imaging sensors by reproducibly printing an array of photopolymerizable sensing elements, containing a pH sensitive indicator, on the surface of an optical fiber image guide. The reproducibility of the microjet printing process is excellent for microdot (i.e. micron-sized polymer) sensor diameter (92.2 {+-} 2.2 microns), height (35.0 {+-} 1.0 microns), and roundness (0.00072 {+-} 0.00023). pH sensors were evaluated in terms of pH sensing ability ({le}2% sensor variation), response time, and hysteresis using a custom fluorescence imaging system. In addition, the microjet technique has distinct advantages over other fabrication methods, which are discussed in detail.
Date: March 1, 2005
Creator: Carter, J C; Alvis, R M; Brown, S B; Langry, K C; Wilson, T S; McBride, M T et al.
Partner: UNT Libraries Government Documents Department

Adaptive control of femtosecond pulse propagation in optical fibers

Description: We present an adaptive control loop that synthesizes fs-pulses that are self-correcting for higher order nonlinear effects when launched in a conventional single-mode fiber, nearly preserving the initial (t{approx}200 fs) pulse duration.
Date: January 1, 2001
Creator: Omenetto, F. G. (Fiorenzo G.); Taylor, Antoinette J.,; Moores, M. D. (Mark D.) & Reitze, David H.
Partner: UNT Libraries Government Documents Department

Measurements at 351 nm of temporal dispersion in fibers

Description: 1. Temporal dispersion at 351-nm was measured in the following: a 35-m bundle of 19 each 50-µm-core fibers, a companion 35-m single fiber, a 100-µm-core single fiber (at 4 lengths), and a 50-µm-core single fiber (two samples, 7 lengths). The 50-µm-core fiber was from preform #24; the 100-µm-core fiber was a prototype version having a thick cladding. All of the fibers were developed and manufactured at the Vavilov State Optical Institute, St. Petersburg, Russia. 2. Dispersion measurements were made by propagating a 20-ps 351-nm pulse through the fiber under test and recording the output on an S20 streak camera. The width of the pulse transmitted by the fiber was compared to that of a fraction of the pulse that had propagated over an air path. Values of dispersion were calculated as, D = {radical}(F² - A²) , where F and A are the full widths at half maximum (FWHM) for, respectively, the fiber-path and the air-path streaks. 3. In each of the experiments, the measured dispersion increased with counts in the streak record, which in principle, are proportional to intensity in the fiber. Measured values of dispersion ranged from about 0.6 to 1.0 ps/m for the single fibers. 4. The measured FWHMs of both the fiber-path pulse and the air-path pulse increased with increase in counts in the streak record. The rate of broadening was greatest for the fiber-path pulse, and the broadening of that pulse was the primary cause for the dependence of dispersion on counts in the streak record. Pulse broadening with increase in counts is symptomatic of camera saturation, but it is difficult to understand why saturation should have effected the fiber-path pulses more strongly. 5. There were spatial anomalies in the streak records of the output pulses from some of the fibers. Emission by the bundle ...
Date: November 4, 1998
Creator: Griffith, R; Milam, D; Sell, W & Thompson, C
Partner: UNT Libraries Government Documents Department

GFOC Project results: High Temperature / High Pressure, Hydrogen Tolerant Optical Fiber

Description: Tests results are given for exposure of multimode optical fiber to high temperatures (300 deg. C) and high partial pressure (15 bar) hydrogen. These results demonstrate that fluorine down doped optical fibers are much more hydrogen tolerant than traditional germanium doped multimode optical fibers. Also demonstrated is the similar hydrogen tolerance of carbon coated and non-carbon coated fibers. Model for reversible H2 impact in fiber versus T{sup o}C and H2 pressure is given. These results have significant impact for the longevity of use for distributed temperature sensing applications in harsh environments such as geothermal wells.
Date: February 12, 2012
Creator: Burov, E.; Pastouret, A.; Aldea, E.; Overton, B.; Gooijer, F. & Bergonzo, A.
Partner: UNT Libraries Government Documents Department

Laser Injection Optics for High-Intensity Transmission in Multimode Fibers

Description: An increasing number of applications are requiring fiber transmission of high-intensity laser pulses. The authors particular interests have led them to examine carefully the fiber transmission of Q-switched pulses from multimode Nd:YAG lasers at their fundamental wavelength. The maximum pulse energy that can be transmitted through a particular fiber is limited by the onset of laser-induced breakdown and damage mechanisms. Laser breakdown at the fiber entrance face is often the first limiting process to be encountered, but other mechanisms can result in catastrophic damage at either fiber face, within the initial entry segment of the fiber, and at other internal sites along the fiber path. In the course of their studies they have examined a number of factors that govern the relative importance of different mechanisms, including laser characteristics, the design and alignment of injection optics, fiber end-face preparation, and fiber routing. The present study emphasizes the important criteria for injection optics in high-intensity fiber transmission, and illustrates the opportunities that now exist for innovative designs of optics to meet these criteria. The consideration of diffractive optics to achieve desired injection criteria began in 1993, and they have evaluated a progression of designs since that time. In the present study, two recent designs for injection optics are compared by testing a sufficient number of fibers with each design to establish statistics for the onset of laser-induced breakdown and damage. In this testing they attempted to hold constant other factors that can influence damage statistics. Both designs performed well, although one was less successful in meeting all injection criteria and consequently showed a susceptibility to a particular damage process.
Date: August 29, 2000
Creator: SETCHELL,ROBERT E.
Partner: UNT Libraries Government Documents Department

ORNL/IAT ARMATURE DIAGNOSTICS DEMONSTRATION TEST REPORT

Description: This test established feasibility for 'on the fly' temperature measurements of rail gun projectiles. In addition, an approach for projectile velocity measurement was also demonstrated. Insight was gained into other useful optical and fiberoptic diagnostic approaches. Instantaneous diagnostics could be critical for achieving further improvements in rail gun operation. They have the potential to enable design enhancements by providing information on the state of the armature and its relationship to the rail as it proceeds down the bore. To that end, the following was accomplished: (1) Optical fibers successfully delivered optical excitation and returned reflective and fluorescence signals as desired. (2) Luminescent coatings survived multiple firings--approximately 40 shots. (3) Optical triggering effectively synchronized an ultraviolet laser pulse to strike the moving armature. (4) Velocity measurements were successfully accomplished by either triggering on the armature front edge using two red diode lasers or by using a single laser and grooved marks a known distance apart on the armature surface. (5) Velocities ranged from 19 to 88 m/s. (6) Temperatures of 30 to 92 C were measured with a precision of about 2 C-: (a) This precision was achieved with a single laser shot and (b) Motion effect was observed but a methodology adequately corrected the result. The correction was only about 2 C. (7) Adequate signal-to-noise and measurement precision was achieved with a single laser shot.
Date: March 1, 2005
Creator: Allison, Stephen W; Cates, Michael R; Goedeke, Shawn; Crawford, M. T.; Ferraro, S. B. & Akerman, A.
Partner: UNT Libraries Government Documents Department

The Central laser facility at the Pierre Auger Observatory

Description: The Central Laser Facility is located near the middle of the Pierre Auger Observatory in Argentina. It features a UV laser and optics that direct a beam of calibrated pulsed light into the sky. Light scattered from this beam produces tracks in the Auger optical detectors which normally record nitrogen fluorescence tracks from cosmic ray air showers. The Central Laser Facility provides a ''test beam'' to investigate properties of the atmosphere and the fluorescence detectors. The laser can send light via optical fiber simultaneously to the nearest surface detector tank for hybrid timing analyses. We describe the facility and show some examples of its many uses.
Date: July 1, 2005
Creator: Arqueros, F.; Bellido, J.; Covault, C.; D'Urso, D.; Di Giulio, C.; Facal, P. et al.
Partner: UNT Libraries Government Documents Department

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: Spectroscopy of Mo{sub 6}Cl{sub 12} immobilized in a sol-gel matrix and heated to 200 C has been performed. Oxygen quenching of the luminescence was observed. Aging Mo{sub 6}Cl{sub 12} to temperatures above 250 C converts the canary yellow Mo{sub 6}Cl{sub 12} to a non-luminescent gray solid. Preliminary experiments point to oxidation of the clusters as the likely cause of thermally induced changes in the physical and optical properties of the clusters.
Date: September 30, 2003
Creator: Baker, Gregory L.; Ghosh, Ruby N. & Osborn, D. J.
Partner: UNT Libraries Government Documents Department

On the Theory of the Modulation Instability in Optical Fiber and Laser Amplifiers

Description: The modulation instability (MI) in optical fiber amplifiers and lasers with anomalous dispersion leads to CW beam breakup and the growth of multiple pulses. This can be both a detrimental effect, limiting the performance of amplifiers, and also an underlying physical mechanism in the operation of MI-based devices. Here we revisit the analytical theory of MI in fiber optical amplifiers. The results of the exact theory are compared with the previously used adiabatic approximation model, and the range of applicability of the latter is determined. The same technique is applicable to the study of spatial MI in solid state laser amplifiers and MI in non-uniform media.
Date: November 3, 2010
Creator: Rubenchik, A M; Turitsyn, S K & Fedoruk, M P
Partner: UNT Libraries Government Documents Department

Sapphire Fiber Optics Sensors for Engine Test Instrumentation

Description: This document is the final report for the Cooperative Research and Development Agreement (CRADA) between UT-Battelle and Prime Photonics, Inc. The purpose of this CRADA was to improve the properties of single crystal sapphire optical fibers for sensor applications. A reactive coating process was developed to form a magnesium aluminate spinel cladding on sapphire optical fibers. The resulting clad fiber had a numerical aperture, NA, of 0.09 as compared with 0.83 for the unclad fiber, dramatically enhancing its usefulness for sensor applications. Because the process allows one to control the diameter of the sapphire core within the fiber, it may be possible using this technology to develop waveguides that approach single-mode transmission character.
Date: September 19, 2003
Creator: Janney, MA
Partner: UNT Libraries Government Documents Department

An approach to multiplicity counting for a versatile new sensor for plutonium assay with a very short die-away time, and independent measurements of neutrons and gamma rays

Description: A unique detector design incorporating a {sup 6}Li-based capture medium, ZnS scintillator, and wavelength shifting optical fibers is the basis of a new neutron coincidence counter for measurements of plutonium in highly-impure residues. The sensor elements have a high efficiency for detecting neutrons and exhibit excellent gamma-ray discrimination based on pulse-shape analysis. The short die-away time of the counter that is based on these detector elements allows coincidence-gate settings shorter than 10 microseconds. This qualifies the technology for measurements of materials with high yields of uncorrelated neutrons from {sup 241}Am(alpha,n) reactions. The characteristics of the new neutron counter will be illustrated with test data from measurements of plutonium, {sup 252}Cf, and gamma-ray sources. The integrated electronics design of the new detector also permits the simultaneous but independent measurement of both neutrons and gamma rays. Recent test results that illustrate some unique applications of the sensor's versatility will also be presented.
Date: January 1, 2002
Creator: Belian, A. B. (Anthony B.); Browne, M. C. (Michael C.); Clay, W. A. (William A.); Geist, W. H. (William H.); Nguyen, H.; Ianakiev, K. D. et al.
Partner: UNT Libraries Government Documents Department

Modeling femtosecond pulse propagation in optical fibers.

Description: Femtosecond pulse propagation in optical fibers requires consideration of higher-order nonlinear effects when implementing the non-linear Schroedinger equation. We show excellent agreement of our model with experimental results both for the temporal and phase features of the pulses. Ultrafast pulse propagation in optical fibers presents a number of challenges given the effect of nonlinearities which become important on such a short time scale. The modeling of femtosecond pulse propagation becomes, consequently, a harder task which has to account for all these effects. In this work, we have included higher order corrections in the non-linear Schroedinger equation and compared the numerical simulation results with experimental data. Our work, besides taking into account the temporal evolution of the pulse, keeps into account also the phase behavior of the electric field, which we compare with experimental results obtained with Frequency Resolved Optical Gating [l]. We also account for self-frequency shift of the pulse and obtain excellent agreement with the experimental results on the Raman shift.
Date: January 1, 2001
Creator: Chung, Y. J. (Yeo-Jin); Schaefer, T. B. (Tobias B.); Gabitov, I. R. (Ildar R.); Omenetto, F. G. (Fiorenzo G.) & Taylor, Antoinette J.,
Partner: UNT Libraries Government Documents Department

High Average Power, High Energy Short Pulse Fiber Laser System

Description: Recently continuous wave fiber laser systems with output powers in excess of 500W with good beam quality have been demonstrated [1]. High energy, ultrafast, chirped pulsed fiber laser systems have achieved record output energies of 1mJ [2]. However, these high-energy systems have not been scaled beyond a few watts of average output power. Fiber laser systems are attractive for many applications because they offer the promise of high efficiency, compact, robust systems that are turn key. Applications such as cutting, drilling and materials processing, front end systems for high energy pulsed lasers (such as petawatts) and laser based sources of high spatial coherence, high flux x-rays all require high energy short pulses and two of the three of these applications also require high average power. The challenge in creating a high energy chirped pulse fiber laser system is to find a way to scale the output energy while avoiding nonlinear effects and maintaining good beam quality in the amplifier fiber. To this end, our 3-year LDRD program sought to demonstrate a high energy, high average power fiber laser system. This work included exploring designs of large mode area optical fiber amplifiers for high energy systems as well as understanding the issues associated chirped pulse amplification in optical fiber amplifier systems.
Date: November 13, 2007
Creator: Messerly, M J
Partner: UNT Libraries Government Documents Department

A high-speed four-channel infrared pyrometer

Description: A high-speed, four-wavelength pyrometer has been developed for dynamic temperature measurements on samples that are heated by shock compression. The pyrometer uses a pair of off-axis parabolic mirrors to collect radiance emitted from a target of 1 mm in diameter. A single optical fiber delivers the collected radiant flux to the detector housing. Three dichroic beam splitters are used to spectrally split the light into four beams that are then focused onto an equal number of LN2-cooled InSb photodetectors. Broad bandwidth interference filters that are nominally centered at 1.8, 2.4, 3.4, and 5.0 {micro}m define the wavelength ranges of the four channels. The blackbody-temperature threshold of the pyrometer is at about 400 K. The signals are recorded at intervals as short as 20 ns using a four-channel digital oscilloscope. Procedures for calibration and temperature measurements are described.
Date: January 1, 2002
Creator: Boboridis, K. & Obst, A. W. (Andrew W.)
Partner: UNT Libraries Government Documents Department

Adaptive control in optical fibers

Description: Adpative control in combination with ultrafast pulse shaping provides a compelling approach to defeat dispersion, distortion and harness nonlinear phenomena on the femtosecond timescale. Ultrafast pulses propagating in optical fibers generate a number of linear and nonlinear effects which affect the pulse during its travel. The main causes stem from the dependence of the index of refraction on frequency (given that short pulses have a large bandwidth) and from the so-called self-action effects which involve the dependence of the index of refraction on the pulse intensity (which is high given that the pulse energy is confined to a very short amount of time).
Date: January 1, 2002
Creator: Omenetto, F. G. (Fiorenzo G.)
Partner: UNT Libraries Government Documents Department

On the Theory of the Modulation Instability in Optical Fibre Amplifiers

Description: The modulation instability (MI) in optical fiber amplifiers and lasers with anomalous dispersion leads to CW radiation break-up and growth of multiple pulses. This can be both a detrimental effect limiting the performance of amplifiers, and also an underlying physical mechanism in the operation of MI-based devices. Here we revisit the analytical theory of MI in fiber optical amplifiers. The results of the exact theory are compared with the previously used adiabatic approximation model and the range of applicability of the later is determined.
Date: May 10, 2010
Creator: Turitsyn, S K; Rubenchik, A M & Fedoruk, M P
Partner: UNT Libraries Government Documents Department

High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry

Description: We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.
Date: March 4, 2009
Creator: Duden, Thomas & Radmilovic, Velimir
Partner: UNT Libraries Government Documents Department

Detection of Unauthorized Construction Equipment in Pipeline Right-of-Ways

Description: The leading cause of incidents on transmission pipelines is damage by third-party construction equipment. A single incident can be devastating, causing death and millions of dollars of property loss. This damage would be prevented if potentially hazardous construction equipment could be detected, identified, and an alert given before the pipeline is hit. Currently there is no method for continuously monitoring a pipeline right-of-way. Instead, companies periodically walk or fly over the pipeline to find unauthorized construction activities. Gas Technology Institute (GTI) is developing a system to solve this problem by using an optical fiber buried above the pipeline as a distributed sensor. A custom optical time domain reflectometer (OTDR) is used to interrogate the fiber. Key issues in the development of this technology are the ability to detect encroachment and the ability to discriminate among potentially hazardous and benign encroachments. Advantages of the reflectometry technique are the ability to accurately pinpoint the location of the construction activity and the ability to separately monitor simultaneously occurring events. The basic concept of using OTDR with an optical fiber buried above the pipeline to detect encroachment of construction equipment into the right of way works. Sufficiently rapid time response is possible; permitting discrimination between encroachment types. Additional work is required to improve the system into a practical device.
Date: September 30, 2004
Creator: Givens, Maurice & Huebler, James E.
Partner: UNT Libraries Government Documents Department

CLASP (Capture and Locking alignment Spring Positioner): A micromachined fiber auto-positioning device

Description: This work provides a method of mechanical alignment of an array of single mode fibers to an array of optical devices. The technique uses a micromachined metal spring, which captures a vertical, pre- positioned fiber, moves it into accurate alignment, and holds it for attachment. The spring is fabricated from electroplated mickel, using photodefined polyimide as a plating mask. The nickel is plated about 80 {mu}m thick, so that a large fiber depth is captured. In one application, the nickel springs can be aligned to optics on the back side of the substrate. This entire concept is referred to as CLASP (Capture and Locking Alignment Spring Positioner). These springs can be used for general alignment and capture of any fiber to any optical input or output device. Passive alignment of fiber arrays to {plus}/{minus} 2{mu}m accuracy has been demonstrated, with a clear path to improved accuracy.
Date: March 1, 1996
Creator: Kravitz, S. H.; Word, J. C.; Bauer, T. M.; Seigal, P. K. & Armendariz, M. G.
Partner: UNT Libraries Government Documents Department

DETECTION OF UNAUTHORIZED CONSTRUCTION EQUIPMENT IN PIPELINE RIGHT-OF-WAYS

Description: Natural gas transmission companies mark the right-of-way areas where pipelines are buried with warning signs to prevent accidental third-party damage. Nevertheless, pipelines are sometimes damaged by third-party construction equipment. A single incident can be devastating, causing death and millions of dollars of property loss. This damage would be prevented if potentially hazardous construction equipment could be detected, identified, and an alert given before the pipeline was damaged. The Gas Technology Institute (GTI) is developing a system to solve this problem by using an optical fiber as a distributed sensor and interrogating the fiber with an optical time domain reflectometer. Key issues are the ability to detect encroachment and the ability to discriminate among potentially hazardous and benign encroachments. The work performed in the second quarter of the project includes design of the instrument, selection of the key components, and beginning programming of the custom optical time domain reflectometer. Work included an assessment of two other approaches to measuring strain and vibrations in an extended optical fiber sensor.
Date: April 26, 2002
Creator: Huebler, James E.
Partner: UNT Libraries Government Documents Department