Geoffrey A. Cranch

United States Naval Research Laboratory

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Clay K. Kirkendall

United States Naval Research Laboratory

Gary A. Miller

United States Naval Research Laboratory

Gordon M. H. Flockhart

University of Strathclyde

J.W. Lou

Zhejiang Shuren University

Phillip J. Nash

TGS (United Kingdom)

Scott Foster

Australian Government

Charles G. Askins

Sotera Defense Solutions (United States)

K. B. Fournier

Lawrence Livermore National Laboratory

J. Grün

United States Naval Research Laboratory

Joseph D. Hart

United States Naval Research Laboratory

Cooperative Institutions

Acoustical Society of America

207

Scripps Institution of Oceanography

194

United States Naval Research Laboratory

Google (United States)

Optical Sciences (United States)

Centre National de la Recherche Scientifique

University of California, San Diego

University of Maryland, College Park

K Lab (United States)

University of Michigan–Ann Arbor

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Remotely-Interrogated Three-Axis Fiber Laser Magnetometer

IEEE Sensors Journal (2012)

Geoffrey A. Cranch Gary A. Miller Charles G. Askins R.E. Bartolo Clay K. Kirkendall

A fiber optic magnetic field sensor node designed for seabed-mounted surveillance arrays, incorporating three orthogonally mounted magnetic field sensors and a microelectomechancial systems inclinometer, is described. Each sensor comprises a current carrying nonmagnetic bridge, which experiences the Lorentz force generated in a magnetic field. A metalized fiber laser attached to the bridge measures the induced strain. The operating principle and fundamental performance of the sensor as well as relevant performance parameters are described. Measured data illustrating the sensor and node performance in laboratory tests are presented. Less than 2 nanoTesla/Hz1/2 resolution at frequencies from 0.002 to 10 Hz is achieved with only 75 mA-rms of current. The sensor node is separated from the interrogation electronics with a 1-km fiber optic cable (extendable to 10 km) and qualified to an operating depth of 100 m. Methods to further improve the magnetometer performance are also discussed.

10.1109/jsen.2012.2217126

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Citations (3)

Scaled experiments on cavity confined explosions in limestone and poly(methyl methacrylate)

Journal of Applied Physics (2019)

Geoffrey A. Cranch J. Grün C. Zulick J. Weaver K. B. Fournier

A scaled experiment comprising a laser-driven explosion in a cavity is used to characterize the coupling of mechanical energy into the surrounding solid material. Experiments are performed using poly(methyl methacrylate) and dry Salem limestone as the explosion containment blocks materials, in which are milled scaled spherical cavities of various dimensions. Measurements of the coupled shock, taken with fiber optic probes at the cavity wall, show the critical radius where wall deformation transitions from plastic to elastic deformation. These measurements also provide a diagnostic of the air blast, which is validated against GEODYN simulation code. The measurement of the coupled shock amplitude taken farther from the wall in the linear region indicates increased coupling efficiency in small cavities over the range of scaled cavity radii from 6 to 20 m/kt1/3, a phenomenon not previously observed in experiments. A comparison of results taken in this experiment with a parallel experiment using high explosive (HE) as the source shows that coupled shocks generated with HE are characteristically different with much larger amplitude than those produced by a high energy density laser-driven source with the same yield. This experimental technique potentially provides a rapid and cost-effective method to analyze the consequences of a full-scale, low yield, buried explosion.

Cavity wall

10.1063/1.5109376

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Citations (1)

Coherent light transmission properties of commercial photonic crystal hollow core optical fiber

Applied Optics (2015)

Geoffrey A. Cranch Gary A. Miller

Photonic crystal hollow core fiber (PC-HCF) has enabled many exciting new applications in nonlinear optics and spectroscopy. However, to date there has been less impact in coherent applications where preservation of optical phase over long fiber lengths is crucial. This paper presents characteristics of three commercially available PC-HCFs relevant to coherent applications including higher-order mode analysis, birefringence and polarization-dependent loss, and their impact on coherent light transmission in PC-HCF. Multipath interference due to higher-order mode propagation and Fresnel reflection is shown to generate excess intensity noise in transmission, which can be suppressed by up to 20 dB through high frequency phase modulation of the source laser. To demonstrate the potential of PC-HCF in high performance sensing, a Mach-Zehnder interferometer (MZI) incorporating 10 m of PC-HCF in each arm is characterized and demonstrates a phase resolution (59×10(-9) rad/Hz(1/2) at 30 kHz) close to the shot noise limit, which is better than can be achieved in a MZI made with the same length of single mode solid core fiber because of the limit set by fundamental thermodynamic noise (74×10(-9) rad/Hz(1/2) at 30 kHz).

10.1364/ao.54.0000f8

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Citations (16)

Fiber Optic Distributed Sensing for Ship Hull Monitoring on the Expeditionary Fast Transport Ship

26th International Conference on Optical Fiber Sensors (2022)

Caitlin R. S. Williams Joseph D. Hart Seth Meiselman S. Varma J.W. Lou

Distributed fiber optic strain and temperature measurements are demonstrated on an Expeditionary Fast Transport ship during normal operation for real-time condition monitoring.

10.1364/ofs.2022.w2.5

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Citations (0)

DFB Fiber Laser Magnetic Field Sensor Based on the Lorentz Force

Optical Fiber Sensors (2006)

Geoffrey A. Cranch Gordon M. H. Flockhart Clay K. Kirkendall

A high sensitivity DFB fiber laser based DC magnetic field sensor is presented. The laser is mounted on a current carrying conductor which vibrates due to the Lorentzian force generated by an external magnetic field.

Lorentz force

10.1364/ofs.2006.tuc2

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Citations (8)

Reduction of Intensity Noise in Hollow Core Optical Fiber Using Angle-Cleaved Splices

IEEE Photonics Technology Letters (2015)

Gary A. Miller Geoffrey A. Cranch

When spliced to solid core optical fiber, a hollow core optical fiber (HCF) exhibits multipath interference. Reflections at the air/glass interfaces add coherently in transmission, producing intensity fluctuations. This can lead to excess intensity noise at the output of a fiber segment. In this letter, angle-cleaved splices were performed on HCFs to reduce this noise without significant alteration of the fiber's optical properties. Cleave angles ranging from 7° to 12° produced splices with return losses less than -50 dB and excess insertion losses typically around 1 or 2 dB. A 37-dB reduction in intensity noise over a flat-cleaved splice was achieved with negligible increase in higher order mode generation or polarization-dependent loss.

Relative intensity noise

Transmission loss

10.1109/lpt.2015.2496873

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Citations (16)

Characterization of a high mechanical-Q fiber laser Lorentz force dc magnetometer

Review of Scientific Instruments (2011)

Geoffrey A. Cranch Charles G. Askins Gary A. Miller Clay K. Kirkendall

A magnetic field sensor is described based on coupling the field into a time varying strain in a fiber laser strain sensor, through the Lorentzian force. A conducting bridge carries an ac current and oscillates at resonance in the presence of a magnetic field. A fiber laser strain sensor attached to the ribbon measures the deflections. The quality factor is shown to be limited by air damping resulting in a measurement resolution of 704 pT/Hz(1/2)±10% at ambient pressure and 360 pT/Hz(1/2)±10% at a reduced pressure of 1700 Pa at 1 Hz and 75 mA (rms).

Lorentz force

10.1063/1.3580631

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Citations (7)

Optical Fiber Sensors: introduction to the feature issue

Applied Optics (2023)

Geoffrey A. Cranch Michel J. F. Digonnet Peter D. Dragic Kara Peters Axel Schülzgen

This special issue contains a collection of papers on optical fiber sensors that were originally presented and published in a more succinct form in conjunction with the 27th International Conference on Optical Fiber Sensors (OFS) held in Alexandria, Virginia, United States, from 29th August to 2nd September, 2022.

Conjunction (astronomy)

Feature (linguistics)

10.1364/ao.495373

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Characterization of spin polarization for cesium vapor confined within hollow core fibers

Pierre M. Bouzi J.W. Lou Gary A. Miller Geoffrey A. Cranch Fredrik K. Fatemi

We have performed time-resolved measurements on cesium vapor to measure the dependence of the spin relaxation time on confinement area. Lifetime results obtained for cesium vapor trapped inside capillaries with diameters ranging from 75 μm to 1.4 mm are up to 75% shorter than that obtained within a 4.5 cm chamber.

Caesium

Characterization

10.1109/fcs.2016.7546758

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Experimental evidence for the thermal origin of1/ffrequency noise in erbium-doped fiber lasers

Physical Review A (2009)

Scott Foster Geoffrey A. Cranch Alexei Tikhomirov

We present experimental evidence in support of the recent theoretical proposal that intrinsic $1/f$ frequency noise in short cavity erbium-doped fiber lasers is of thermal origin. We demonstrate that the power spectral density of frequency noise in distributed-feedback fiber lasers (DFB FL) exhibits predicted ${T}^{2}$ temperature dependence across all frequencies over a temperature range of almost 200 K. This temperature dependence is observed both in direct interferometric measurements of frequency noise in a single mode DFB FL and noninterferometric measurements of polarization-beat-frequency noise in a dual frequency DFB FL. It is also shown that frequency noise of orthogonal polarization modes in the dual frequency DFB FL is substantially correlated providing a strong indication of a common origin.

Atmospheric temperature range

10.1103/physreva.79.053802

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Citations (58)