Fiber Optic Sensors: Fundamentals And Applications

Fiber Optic Sensors:Fundamentals and ApplicationsSeptember, 2015David Krohn, Ph.D.Light Wave Venture LLCdkrohn@lightwaveventure.com203-248-1475

Presentation Focus The major focus of this presentation will be ondistributive fiber optic sensors which has seenthe greatest usage However, key applications for point sensorswill be discussed The market dynamics will be covered briefly

Fiber Optic Sensor Commercialization EvolutionSensorsTelecom1975R&D- Military and IndustrialR&D- Telecommunications1980Laboratory DevicesMultimode Systems; Mb/s transmission19851st Industrial Applications and MilitarySystemsAdvent of Single Mode Systems; MajorInfrastructure Build19901st Commercial Gyroscope; MedicalApplicationsEDFA; Undersea Systems; Gb/stransmission19951st Oil & Gas Field Trials and SmartStructures. First FBG interrogators.Optical Component Advancements andDWDM20001st Commercial Oil & Gas SystemsOptical Networks; Market Peak at 18B; Tb/s transmission2010Broad commercialization of sensors &instrumentationTrials for 100Gb systems. R&D onmulti-core fibers2014Key enabling technology for NorthAmerican energy independence

Advantages of Fiber Optic Sensors Nonelectrical Explosion proof Often do not require contact Remotable Small size and light weight Allow access into normally inaccessible areas Potentially easy to install (EMI) Immune to radio frequency interference (RFI) and electromagnetic interference (EMI) Solid state reliability High accuracy Can be interfaced with data communication systems Secure data transmission Resistant to ionizing radiation Can facilitate distributed sensing.Can function in harsh environments

Light Modulation Effects Used by Fiber Sensors to Detect a Physical Parameter

Classification of Optical Fiber Sensors by Transducing ApproachFiber itself is YBRIDTransduceracts on the fiberFiber carrieslight in and outof the device

Classification of Optical Fiber Sensors According to their Topology

Fiber Optic Distributed SensorsFiber Optic Distributed SensorsInterferometricBragg Grating§Multi Point§ContinuousMulti PointContinuousBrillouin (DTSS)Continuous Temp Strain Vibration TempRayleigh (DAS)ContinuousFrequencyIntensityPhase Temp Strain VibrationRaman (DTS) Temp Strain Vibration Acoustic Pulse

Phase Modulated Sensors

InterferometersMach–Zehnder interferometer configurationMichelson Interferometer configuration

InterferometersFabry–Perot interferometer configurationSagnac interferometer configuration

Phase Detection Change in length due to mechanical or thermal strain will cause a phasechange (Mach-Zehnder interferometer)2πφ φ [n1 L n1 L ]λ0Phase change of a light wave through an optical fiber oforiginal length L that has been stretched by a length ? LIntensity versus relative phase shifts due to constructiveand destructive interference Provides extremely high resolution Noise issues such as phase noise and multimode noise are addressed inthe detection schemes

Fabry-Perot Interferometric SensorConceptsAir GapReflectionsBraggGratingLLFiberLL

Distributed Interferometric SensorConfigurations

Interferometric Sensing Performance Long term accuracy - 1% Resolution - 0.01 microstrain Position Resolution – 1 meter in 10 Kmlength Can monitor dynamic strain over a broadrange of frequencies – vibration signature There is a trade-off between distancerange and frequency bandwidth (due totime-of-flight limitations).

How Does a Fiber Optic Hydrophone Work?Hollow Mandrel –sensitive toPressureVariationsSolid Mandrel –Insensitive toPressureVariationsSource: NorthropGrumman

FOS Milestones:Hydrophone DevelopmentInstalled on 62 USS Virginia class nuclearsubmarinesFO Planar hydrophone Arrays (three flat panels mounted lowalong either side of the hull), as well as two high frequencyactive sonars mounted in the sail and keel (under the bow).The result of 15 years of R&D and 140M of investment!

Wavelength Modulated Sensors

Fiber Bragg GratingsReflectedSignalTransmittedSignal

Fiber Bragg Grating Sensor

.Bragg Grating SensorThe change in wavelength, associated with both strain and temperature effects, isgiven by: dn 2 n λ B 1 P12 v ( P11 P12 ) ]ε α dT T ,n 2 where:e the applied strain,P11, P12 the stress optic coefficient,a the coefficient of thermal expansion,? Poisson’s ratio,n the refractive index of the core, and? T the temperature change.For constant temperaturenThis relationship corresponds to 1 nm of wavelength change for 100 microstrain at a wavelength of1300 nm.For the case of zero applied strain1 λ B 6.67 10 6 / Cλ B TAt 1300 nm, a change in temperature of 1 C results in a Bragg wavelength shift (?B) of 0.01 nm.

Bragg Grating Sensor Response

Bragg Grating SensorsInput SignalBraggGratingOptical FiberReflectedSignalStrain Induced SpectralShiftPerformance Resolution - 0.5 microstrain Long term accuracy - 1% Up to 20 sensing points in C band Can monitor low frequency dynamic strain Temperature resolution of 1oC Strain / temperature discrimination isrequired

Bragg Grating Distributed Sensing System ConfigurationsWDMTDM/WDM

High Capacity WDM DistributedSensing System Using Bragg GratingsSource: Micron Optics

Bridge Failure in Minneapolis MN

Conceptual Use of Static and Dynamic Strain Monitoring in a BridgeApplication

Strain change with Time Associated with Bridge TrafficSource: Micron Optics

Scattering Based Sensors

Distributed Sensing Applications

Distributed Sensing System Based on Scattering

Emission from Raman, Brillouin andRayleigh Scattering

Raman Scattering Process in Optical FiberSource: Sumitomo & LIOS

Raman Scattering Distributed Temperature Sensing (DTS).

Temperature and Strain Sensitivities forVarious Scattering Effects in Optical Fiber

Raman Scattering Performance Only measures temperature and isindependent of strain. The temperature resolution is 0.5oC The measurement range is up to 15 kmwith a 1 meter spatial resolution (up to25km with a 1.5 meter resolution) of thelocation of the temperature perturbation

Brillouin Scattering Performance The measurement range of up to 30 km. The sensing point associated with a physicalperturbation can be resolved to 1 meter on a 10 kmlength, but accuracy is reduced as distance increases. The strain resolution is 20 microstrain. However, moreadvanced detection schemes can have a strainresolution of 0.1 microstrain. The temperature resolution is 0.5oC While Brillouin scattering is an excellent strain sensortechnology, the response time is about 1 second; andtherefore, is not suitable for vibration measurements.

Mach-Zehnder Interferomter Basedon Rayleigh ScatteringScanning ormance Accuracy - 2 strainSpatial resolution – 1 cmMax. length - 50 metersReflection 1Reflection tReflection1Reflection 2Distance, Frequency

Distributed Acoustic Sensing (DAS) Based on Rayleigh backscattered light in an opticalfiber (single mode or multi mode) It senses all points along the fiber and monitorsacoustic perturbations to the fiber Specifications– Frequency range - 1mHz to 100kHz– Spatial resolution - 1 m– Length – 50 km Strong applications– Oil and gas – seismic– Pipeline monitoring

Oil & Gas Applications

Fiber Optic Sensors in Oil & GasSource: Weatherford

DTS - SAGD Steam Assisted Gravity Drainage (SAGD) is an enhancedoil recovery technology for producing heavy crude oilutilizing steam injection80% of oil sands require enhanced recovery techniquessuch as SAGDOptimizing steam management optimizes reservoirproduction, reduces costs and limits emissionMonitoring the temperature profile of the steam chambergrowth is key to process and efficiency improvementsDistributed fiber optic temperature sensing systems haveprovided the monitoring capabilitySource: Petrospec

Advent of Permanent Ocean BottomCable (OBC) Seismic Systems Seismic reservoir management tool tooptimize production Major franchises formed– Optical System– Deployment– Interpretation– Oil Company SponsorsFiber Optics: reach, channel count; reliabilityEarly growth stageBetween 20-50M cost per field to customerLarge incremental growth potentialCourtesy Petroleum Geo-ServicesSource - Qorex

Pipeline Distributed Fiber OpticMonitoring System Fiber opticinterferometricarray monitors Interferometricabout 25 Kmand DASsystems can monitor 25 Multiplearrayskm or longerof DTScoverand hundredsDTSS systemskm been used tohavemonitorleaks which Data transferredthroughcause wirelessa localnodetemperaturedrop In evaluationtrialsSource: Sabeus

Pipeline Leak Detection(Distributed Brillouin Scattering)Source: Omnisens

DAS Acoustic SignaturesSource: OptaSense

Magnetic and Electric Field Sensors

Fiber Optic Magnetic Field Sensor Architectures

Faraday Rotating OpticAttached Polarizing OpticsLow Verdetconstant in fiberrequires longpath lengthcompared withbulk Faradayrotators

ensor with PiezCoatings Magnetostrictivecoating can be usedfor magnetic fieldsensors High sensitivitypotential

Biophotonic Sensors

Biosensor ConceptIntrinsic Biophotonic SensorsMechanismsAbsorptionScatteringRaman ScatteringIndex of RefractionFluorescenceConceptsEvanescent Wave InteractionPhotonic Bandgap ConfinementFluorescence ArraysFlow Cytrometry

Biophotonic Interaction Modulated Mach-Zehnder Interferometer

Evanescent Wave Fluoroimmunoassay Concept

Fiber Optic Enabled Arrays usingFluorescence for High Speed Screening

Fluorescent Array Microsphere Vapor SensorsFigure 16.14 Fluorescent Array Microsphere Vapor Sensors10

Gyroscopes

Sagnac Effect in a Coiled FiberUsed for Rotation Rate Sensing. (2 LD/ c)

Noise Sources in an Optical FiberGyroscope

Typical Precision FOG Design

Northrop Grumman CommercialInertial Measurement Unit (IMU) withThree Fiber Optic Gyroscopes

Market

FO Sensor Market:Single-Point Sensing2008MedicalPower 3%Industrial8%4%2014Military4%Power4%Oil& Gas2%Medical3%Military4%Oil& 25%CivilInfrastructure29%Total: 194 MillionTotal: 302 Million

Distributed Fiber Optic SensorApplications

Distributed Fiber Optic Sensor Market Forecast:By ApplicationTake away The oil and gasmarket segment willsee a contractionlasting through 2015 asillustrated in theprojections above Price dips aretypically short lived;and, the average pricehas moved back to anupswing in typically 12to 18 months or less

Future Market Opportunities: Low cost sensors/instrumentsà all applications &markets Disposable sensorsà medical & health care Distributed sensorsà oil & gas, smart structures Smart fabricsà geotechnical, medical, aerospace Food industryà water & food safety Environmentalà gas sensing/emissions monitoring,pollution detection and monitoring

Future Possibilities:Optical Integrated FOS

Conclusions The FOS field initiated the transition from lab to commercialization since theearly 80’s. Initial products have targeted military and harsh environment applications(gyro, hydrophones, oil & gas, HV sensing). Commercialization cycles are long, needing 5-20yrs of development Several FOS products have reached maturity and reached commercialsuccess: FOG, DTS, DAS, FBG sensors, etc. The Distributed FOS market was 630 million in 2014 and projected to be 1042 million in 2019. The oil and gas sector represents 46% of the totalmarket The FOS Industry, in general, was blind-sided by the sudden surprise drop inoil prices in early 2015.

Contacts David Krohn– dkrohn@lightwaveventure.com– 203-248-1475 Fiber Optic Sensors Fundamentals andApplications, Fourth Edition, 2014– Available at www.spie.org Photonic Sensor Consortium Market Survey Distributed Fiber Optic Sensing Systems Forecast– Available at Information Gatekeepers hpan@igigroup.com

perturbation can be resolved to 1 meter on a 10 km length, but accuracy is reduced as distance increases. The strain resolution is 20 microstrain. However, more . Fiber Optic Sensors Fundamentals and Applications, Fourth Edition, 2014 Available at www.spie.org -