White Papers

Theory of SNAP devices: basic equations and comparison with the experiment  
M. Sumetsky
Abstract:  A SNAP (Surface Nanoscale Axial Photonics) device consists of an optical fiber with introduced nanoscale effective radius variation, which is coupled to transverse input/output waveguides. The input waveguides excite whispering gallery modes circulating near the fiber surface and slowly propagating along the fiber axis. In this paper, the theory of SNAP devices is developed and applied to the analysis of transmission amplitudes of simplest SNAP models exhibiting a variety of asymmetric Fano resonances and also to the experimental characterization of a SNAP bottle microresonator and to a chain of 10 coupled microresonators. Excellent agreement between the theory and the experiment is demonstrated.

Higher-Order Mode Erbium-Doped Fiber Amplifier with Output Reconversion to the Fundamental Mode 
J.W. Nicholson, J.M. Fini, A. DeSantolo, X. Liu, K. Feder, V.R. Supradeepa, P. Westbrook, E. Monberg, F. DiMarcello, C. Headley, and D.J. DiGiovanni
Abstract:  A CW, higher-order mode, Er-doped-fiber amplifier is demonstrated with output reconversion to the fundamental mode for the first time. Amplification takes place in the LP0,14 mode with an effective area of 6000 μm².

Laser-induced damage to large core optical fiber by high peak power laser 
Xiaoguang Sun and Jie Li
Abstract: In this paper we present a study of laser damage to large core multimode glass optical fibers by high peak laser power of up to 175 kW. Fibers samples prepared with polymer coatings having different refractive indices were tested in a two-point bend tester while transmitting laser light. The peak power used in the experiment clearly differentiated the performance among the samples. A polymer coating having lower refractive index significantly improves the fiber resistance to bending while transmitting laser. This observation provides important insight into the damage mechanism for this particular failure mode.

Anomalous Dispersion in a Solid, Silica-Based Fiber 
S. Ramachandran, S. Ghalmi, J.W. Nicholson, M.F. Yan, P. Wisk, E. Monberg and F.V. Dimarcello
Abstract: We demonstrate an all-solid (nonholey), silica-based fiber with anomalous dispersion at wavelengths where silica material dispersion is negative. 

Lifting Polarization Degeneracy of Modes by Fiber Design: A Platform for Polarization-Insensitive Microbend Fiber Gratings
S. Ramachandran, S. Golowich, M.F. Yan, E. Monberg, F.V. Dimarcello, J. Fleming, S. Ghalmi and P. Wisk
Abstract: Polarization dependence in microbend gratings is an inherent problem, even in perfectly circular fibers, since antisymmetric modes are almost degenerate linear combinations of four distinct, polarization-sensitive modes. 

Dispersion-Tailored Few-Mode Fibers: A Versatile Platform for In-Fiber Photonic Devices
S. Ramachandran
Abstract: In-fiber devices enable a vast array of critical photonic functions ranging from signal conditioning (amplification, dispersion control) to network management (add/drop multiplexers, optical monitoring). 

Novel Fibers for Ultra-Short and High-Power Pulses
S. Ramachandran, J.W. Nicholson and M.F. Yan
Abstract: Light propagation in higher-order modes of few-mode fibers leads to unique dispersive properties that are challenging or impossible to achieve in conventional fibers. 

Investigation of New Erbium Doped Fiber Design with Improved Splicing Performance
Torben Veng and Bera Pálsdóttir
Abstract: An erbium doped fiber (EDF) having a new type of refractive index profile, useful for optimizing fusion splicing abilities, is studied with respect to splice performance and gain characteristics. 

Novel Erbium Doped Fiber for High Power Applications
B.S. Wang, G. Puc, M. Andrejco
Abstract: A novel erbium doped fiber (EDF) designed for high power WDM applications is presented. The fiber design and performance versus numerical aperture and cutoff wavelength are described based on an advanced EDFA simulation model. The optical and spectral characteristics of the high power fiber are shown. Experimental measurement results of this fiber and comparison with typical commercially available EDFs are given. Performance results show that the new EDF is ideal for high power EDFA applications. It features high power conversion efficiency at high pump power, especially with 980 nm pumping, extremely flat gain shape, very low splice loss to typical pigtail fibers, and negligible macro-bending loss. 

Erbium-Doped Fiber Design for Improved Splicing Performance
Torben Veng and Bera Pálsdóttir
Abstract: Fusion splicing is a well-known technique to connect a fiber pair and fusion splicers have been commercially available for this process for a long time. An important feature of a fusion splice is the coupling loss that is influenced by - among other things - the mutual spotsizes of the two fibers involved. Hence, similiar fibers such as standard single mode fibers can be spliced to nearly zero loss whereas dissimiliar fiber pairs may give higher loss. The latter category covers the splice combinations of erbium doped fibers that are often spliced to other fiber types such as the standard single mode fiber. 

Silica Based Erbium Doped Fiber Extending the L-band to 1620+ nm
Inger Pihl Byriel, Bera Pálsdóttir, Matt Andrejco, C. Christian Larsen
Absract: A fiber has been developed for use in extended L-band amplifiers, utilizing the wavelength range from 1565 to 1620 nm. The fiber is silica based and has low splice loss to standard telecommunication fiber. The quantum conversion efficiency is >60%. 

Low Speed Carbon Deposition Process for Hermetic Optical Fibers
Eric A. Lindholm, Jie Li, Adam S. Hokansson, Jaroslaw Abramczyk
Abstract: For optical fibers used in adverse environments, a carbon coating is frequently deposited on the fiber surface to prevent water and hydrogen ingression that lead respectively to strength degradation through fatigue and hydrogen-induced attenuation. The deposition of a hermetic carbon coating onto an optical fiber during the draw process holds a particular challenge when thermallycured specialty coatings are subsequently applied because of the slower drawing rate. In this paper, we report on our efforts to improve the low-speed carbon deposition process by altering the composition and concentration of hydrocarbon precursor gases. The resulting carbon layers have been analyzed for electrical resistance, Raman spectra, coating thickness, and surface roughness, then compared to strength data and dynamic fatigue behavior.

High speed in-line polarimeter with the built-in polarization reference as a sensor in fiber optic transmission systems  
Vitaly Mikhailov, Bryan Rabin, Paul Westbrook
Abstract: We demonstrate the use of a high speed in-line polarimeter as a detector of fiber movement and/or fast polarization rotation. Our system can be used in the lightwave telecommunication networks to detect and locate illegal fiber taps and localize damaging high speed polarization rotation in 100G coherent systems. We also demonstrate that due to its built-in absolute polarization reference, our HiBi polarimeter can be used to detect environmentally induced PM fiber polarization extinction ratio degradation.

Measuring Differential Group Delay and Distributed Scattering in Few Mode Fibers for Mode Division Multiplexing  
J.W. Nicholson, L. Grüner-Nielsen, K. Jespersen, Y. Sun, R. Lingle, D. Jakobsen, and B. Pálsdóttir 
Abstract: Mode division multiplexed systems in few mode fibers has attracted considerable attention as a means to increase the transmission capacity of a single fiber.

Effects of sterilization methods on key properties of specialty optical fibers used in medical devices  
Andrei A. Stolov, Brian E. Slyman, David T. Burgess, Adam S. Hokansson, Jie Li and R. Steve Allen
Abstract: Optical fibers with different types of polymer coatings were exposed to three sterilization conditions: multiple autoclaving, treatment with ethylene oxide and treatment with gamma rays. Effects of different sterilization techniques on key optical and mechanical properties of the fibers are reported. The primary attention is given to behavior of the coatings in harsh sterilization environments. The following four coating/buffer types were investigated: (i) dual acrylate, (ii) polyimide, (iii) silicone/PEEK and (iv) fluoroacrylate hard cladding/ETFE.

Reliability of Optical Fibers in a Cryogenic Environment 
E. Lindholm, A. Stolov, R. Dyer, B. Slyman and D. Burgess
Abstract: Optical fibers with various protective coatings were submerged in liquid nitrogen to 77°K then tested for mechanical and optical reliability.  While all the fibers maintained strength after low-temperature exposure, the optical response varied depending on the protective coating.

Optical Fibers with Polyimide Coatings for Medical Applications
Andrei A. Stolov, Brian E. Slyman, Debra A. Simoff, Adam S. Hokansson, R. Steve Allen and John P. Earnhardt
Abstract: Fiber optics is successfully used in various areas of medicine, including urology, general surgery, ophthalmology,cardiology, endoscopy, dentistry and medical sensing [1 – 4]. One highly useful characteristic of optical fibers is their ability to enter the tiny passageways and hard-to-reach areas of the human body. Hence most medical applications require optical fibers to be relatively small and "exible so as to negotiate the complex curved anatomy of central spaces of vessels in-vivo: such as arteries, veins, gastrointestinal tracts, bronchi, and urinary tracts.

Thermal Stability of Specialty Optical Fibers
Andrei A. Stolov, Debra A. Simoff, and Jie Li.
Abstract: Application of silica optical fibers at elevated temperatures is limited by the thermal stability of their polymer coatings, as thermal degradation in most polymer materials occurs at much lower temperatures than silica, which can result in degradation in the fiber performance. 

Study of Optical Fiber Damage Under Tight Bend with High Optical Power at 2140 nm
Xiaoguang Sun, Jie Li and Adam Hokansson.
Abstract: Silica optical fibers are being increasingly used for delivering laser power in various medical applications. 

Light Propagation with Ultralarge Modal Areas in Optical Fibers
S. Ramachandran, J.W. Nicholson, S. Ghalmi, M.F. Yan, P. Wisk, E. Monberg and F.V. Dimarcello
Abstract: We demonstrate robust single-transverse-mode light propagation in higher-order modes of a fiber, with effective area Aeff ranging from 2100 to 3200 µm2. 

The Thinnest Optical Waveguide: Experimental Test
M. Sumetsky and Y. Dulashko
Abstract: A thin dielectric waveguide with a subwavelength diameter can exhibit very small transmission loss only if its diameter is greater than a threshold value, while for smaller diameters, waveguide loss grows dramatically. 

Optimum Intermediate Fibers for Reducing Interconnection Loss: Exact Solution
Andrew D. Yablon and M. Sumetsky
Abstract: We derive an exact analytical solution for a transmission line of N single-mode intermediate optical fibers that minimize the interconnection loss between any two dissimilar fiber modes that are well described by the paraxial scalar wave equation. 

Optics of Tunneling From Adiabatic Nanotapers
M. Sumetsky
Abstract: A theory of light propagation along adiabatic photonic nanowire tapers (nanotapers) having diameters significantly less than the radiation wavelength λ ~ 1 µm is developed. 

Propagation of Femtosecond Pulses in Large-Mode-Area, Higher-Order-Mode Fiber
J.W. Nicholson, S. Ramachandran, S. Ghalmi, M.F. Yan, P. Wisk, E. Monberg, and F.V. Dimarcello
Abstract: We demonstrate propagation of 14-nJ femtosecond pulses through a large-mode-area, higher order mode fiber with an effective area of 2100 µm2. The pulses propagate stably in the LP07 mode of the fiber through lengths as long as 12 m. 

Effect of Optical Fiber Coating Abrasion on Aging Behavior
Eric A. Lindholm, Rich Heinemann, Brian Slyman, and David Burgess
Abstract: Optical fibers with different protective coatings were abraded then submerged in 50°C water for twenty-eight days. The strength of the abraded and control fibers exposed to zero-stress aging was tracked over time with tensile strength testing. Although the abrasion test represented a severe model of fiber handling, no appreciable strength degradation was detected on the fiber before or after zero-stress aging. 

Optical Microfibers: Fundamentals and Applications
M. Sumetsky
Abstract: Transmission properties and applications of single-mode optical microfibers are reviewed. 

How Thin Can a Microfiber Be and Still Guide Light?
M. Sumetsky
Abstract: For the adiabatically deformed optical fiber the intermode transmission amplitudes and loss vanish exponentially with the characteristic length of the fiber's nonuniformity. 

Fiber Strength and Reliability
Eric Lindholm and Jie Li
Abstract: The varied breaking strength of silica fiber can be attributed to the distribution in flaw severity along the fiber length. Micro-cracks can be inherent to the glass itself or a result of the manufacturing process and handling of the fiber. Fiber strength also degrades with time due to fatigue as a result of crack growth accelerated by interaction with moisture. 

Advanced Topics on Erbium Doped Fibers for High Performance Amplifiers
B.S. Wang, M.J. Andrejco
Abstract: Erbium doped fiber amplifiers have been widely deployed for signal amplification in optical transmission systems. High performance amplifiers require erbium doped fiber with high power conversion efficiency and consistent flat gain spectrum. In addition, all impairments associated with EDF must be under good control. This paper reviews the current status and recent progress on erbium doped fibers, illustrates C and L-band spectral characteristics resulting from different doping compositions, presents some approaches for efficient high power amplifiers, and discusses some EDF nonlinear effects with examples. 

Bending Induced PMD in Spun Erbium Doped Fiber
Peter Borg Gaarde, Tommy Geisler, Poul Kristensen and Bera Pálsdóttir
Abstract: We have measured the DGD induced by bending in both active and passive Erbium Doped Fibers. We demonstrate, both theoretically and experimentally, non-trivial behavior of PMD in spun Erbium Doped Fiber (EDF) when coiled to small diameters. 

Characterization of Gain Spectral Variation of Erbium-Doped Fibers Codoped with Aluminum
B.S. Wang, G. Puc, R. Osnato, B. Pálsdóttir
Abstract: Characteristics of gain spectral variation of EDFs and its dependence on aluminum doping level and fiber mode design are quantitatively studied. Based on experimental data and manufactured fibers with different aluminum levels, the correlation between aluminum concentration and both absorption spectrum and gain flatness is revealed. Gain spectral variation for over a million meters of EDFs manufactured in last several years is presented. The result shows that peak-to-peak spectral shape variation for all these fibers are within 0.8% in a 36 nm C-band window. 

Optimization of Fusion Splice Process for High Numerical Aperture Coupler Fiber and Erbium Doped Fiber
Honggu Jiang, Timothy McMahon, Jie Li
Abstract: Fusion splicing erbium doped fiber (EDF) to other single mode fibers has become more critical as the required overall insertion loss for erbium doped fiber amplifiers (EDFA) has significantly decreased in the last few years. In this paper, we describe and discuss an approach to developing a low loss splice method for fusion splicing high numerical aperture (NA) 980/1600 wavelength-division-multiplexing (WDM) coupler fiber and EDF. The results indicate that the fiber end preparation before the fusion is especially critical for obtaining a low loss splice for the fiber pair. 

Strength and Reliability of Silica Optical Fibers in Automotive Communication Networks
Eric A. Lindholm, Edward Warych & Daniel Whelan
Abstract: Demand for new safety, sensor, control, information and entertainment technologies in automobiles is stretching the data rate limits of communication networks using conventional wiring and plastic-based fibers. Thus far, the switch to high-bandwidth glass optical fibers has been hindered by concerns about the fiber's reliability. In this study, we present zero-stress aging data for glass optical fibers with different protective coatings exposed to environmental conditions relevant to the automotive industry. 

Aging Behavior of Optical Fibers in Aqueous Environments
Eric A. Lindholm, Jie Li, Adam Hokansson, Brian Slyman, and David Burgess
Abstract: Silica optical fibers drawn from a common preform and coated with specialty coatings were exposed to zero-stress aging in various aqueous environments for approximately ten months. The strength of the fiber samples was tracked with two-point bend testing. The onset of an aging “knee” was observed for some fiber samples while other coatings offered enhanced protection from the effects of moisture-induced strength degradation. 

Advances In Design and Development of Optical Fibers for Harsh Environments
Jie Li, Eric A. Lindholm, Jana Horska, and Jaroslaw Abramczyk
Abstract: Optical fiber for harsh environments presents unique design challenges, particularly in coatings required to maintain the properties of the fiber. In a typical harsh environment application, the optical fibers are exposed to water, hydrogen or other harmful chemicals at elevated temperatures, e.g. > 200 °C. The fibers are commonly coated with a thin layer of carbon and further coated with thermosetting polyimide materials that can withstand significantly higher temperature than the common UV cured acrylate coatings. In this paper, we describe our recent efforts in understanding the impact of the environment on the fiber performance and report the advances in improving fiber and coating design to minimize the impact. Along with the discussion of the familiar fiber failure mechanisms, we also show the existence of a unique failure mechanism, i. e. the degradation of coating properties that leads to optical transmission loss. 

Zero-Stress Aging Behavior of Optical Fibers with Various Protective Coatings
Eric A. Lindholm, Jie Li, Adam Hokansson, Brian Slyman & David Burgess
Abstract: Optical fibers with various coatings are subjected to zero-stress soaking in water at room temperature and at 80°C. Change in fiber strength over time is tracked using two-point bend strength testing. The aging behavior of the fibers with different coatings is compared and the results are discussed.
 

Suppression of High-Order Modes in Aircore Microstructure Fiber Designs
John M. Fini
Abstract: Modified designs for hollow-core bandgap fibers with suppressed higher-order modes are proposed.
Numerical simulations demonstrate that index-matched cladding defects can dramatically increase losses of undesirable modes and leave the fundamental well confined. 

Sol-gel Derived Microstructured Fiber: Fabrication and Characterization
Ryan T. Bise and Dennis J. Trevor
Abstract: We discuss a sol-gel casting technique for fabricating microstructured optical fiber. Both the advantages and challenges associated with this fabrication method are outlined. 

Surface Absorption in Microstructured Optical Fibers
RT Bise and DJ Trevor
Abstract: Spectroscopic detection of chemical species SiOH and SiNH2, located at the air/glass interface between the air holes and the silica core of a microstructured fiber is reported. 

Low-Loss High-Strength Microstructured Fiber Fusion Splices Using GRIN Fiber Lenses
AD Yablon and R Bise
Abstract: Gradient-index fiber lenses are used to fabricate high-strength (>100 kpsi) fusion splices between microstructured optical fibers. High coupling efficiencies are attainable (<0.6 dB loss), providing the mode field diameter is at least about 3.5 µm. 

Air-Silica Microstructure Fiber Based Variable Optical Attenuator Device
C Kerbage, J Ging, P Steinvurzel, A Hale, A Yablon, RS Windeler, and BJ Eggleton
Abstract: We present a design for modulating light in an optical fiber, which achieves efficient modal field interaction between the fundamental mode of an air-silica microstructure optical fiber and tunable materials incorporated in the air-holes of the fiber. 

Water-Core Microstructure Fiber for Optical Sensing
JM Fini
Abstract: A novel water-core microstructure fiber design allows nearly ideal guidance for aqueous sensing applicatioins.  The total internal reflection by a microstructured silica-air cladding provides robust confinement of light in a fluid-filled core, if the average cladding index is sufficiently below the index of water.  Numerical results show dramtically improved loss and overlap of light with the sample, compared to evanescent-field fibers, indicating a direct improvement of sensor performance.  A strategy for the improvement of evanescent-wave gas sensors is also discussed.

Effect of Mode Cut-Off on Dispersion in Photonic Bandgap Fibers
J Jasapara, R Bise, T Her, and JW Nicholson
Abstract: The phase dispersion of the fundamental mode in two different photonic bandgap fibers is measures and compared. The difference in dispersion behavior is attributed to the location of the mode cut-off relative to the bandgap. 

Tunable Microstructure Fiber Devices
RS Windeler, C Kerbage, J Jasapara, R Bise, and BJ Eggleton
Abstract: An overview of microstructure fibers and devices is presented. By filling the fiber holes with liquids and manipulating the properties of the liquids, the transmission properties of the fiber can be changed to create tunable devices. 

Electrically Drive Motion of Micro-Fluids in Air-Silica Microstructure Fiber:
Application to Tunable Filter/Attenuator
C Kerbage, RS Windeler, BJ Eggleton, P Mach, M Dolinski, and JA Rogers
Abstract: We present an approach for manipulating light in an optical fiber where efficient modal field interaction is achieved between modes propagating in an air-silica microstructure optical fiber and micro-fluids incorporated in the air-holes of the fiber. We demonstrate this approach in terms of applications to tunable devices. 

Tunable Photonic Band Gap Fiber
RT Bise, RS Windeler, KS Kranz, C Kerbage, BJ Eggleton, and DJ Trevor
Abstract: A photonic band gap fiber has been generated by incorporating a high index fluid into a sol-gel derived microstructured fiber. The band gap positions and widths are tuned by adjusting the temperature.

SNAP: Fabrication of long coupled microresonator chains with sub-angstrom precision
M. Sumetsky and Y. Dulashko
Abstract: Based on the recently-introduced Surface Nanoscale Axial Photonics (SNAP) platform, we demonstrate a chain of 30 coupled SNAP microresonators spaced by 50 micron along an optical fiber, which is fabricated with the precision of 0.7 angstrom and a standard deviation of 0.12 angstrom in effective microresonator radius. To the best of our knowledge, this result surpasses those achieved in other super-low-loss photonic technologies developed to date by two orders of magnitude. The chain exhibits bandgaps in both the discrete and continuous spectrum in excellent agreement with theory. The developed method enables robust fabrication of SNAP devices with sub-angstrom precision.

High Efficiency Cascaded Raman Fiber Laser with Output Power of 204W at 1480nm
V.R. Supradeep, J.W. Nicholson, C. Headley, B. Palsdottir, D. Jakobsen
Abstract: We demonstrate a 1480 nm cascaded Raman fiber laser with a new high efficiency architecture providing a record output power of 204 W and conversion efficiency of 65%. We achieve this through multiple Raman shifts of a high power 1117 nm Yb-doped fiber laser in a single pass configuration mediated at all intermediate wavelengths using a seed source comprising a low power conventional 1480 nm Raman laser. Enhancement in efficiency is achieved by elimination of excess optical loss present in the conventional architecture using a cascaded Raman resonator.

SNAP: Fabrication of long coupled microresonator chains with sub-angstrom precision
M. Sumetsky and Y. Dulashko
Abstract: based on the recently-introduced Surface Nanoscale Axial Photonics (SNAP) platform, we demonstrate a chain of 30 coupled SNAP microresonators spaced by 50 micron along an optical fiber, which is fabricated with the precision of 0.7 angstrom and a standard deviation of 0.12 angstrom in effective microresonator radius. To the best of our knowledge, this result surpasses those achieved in other super-low-loss photonic technologies developed to date by two orders of magnitude. The chain exhibits bandgaps in both the discrete and continuous spectrum in excellent agreement with theory. The developed method enables robust fabrication of SNAP devices with sub-angstrom precision.

Using the OFS TruePhase® IPLM Inline Polarimeter for OSNR Measurement in Optical Systems
Anurag Jain
Abstract: OSNR measurement is a necessity for optical performance monitoring of channels in optical systems, required especially during installation and ongoing maintenance. There are several in-band OSNR measurement ­techniques that make use of polarization, since the optical signal is polarized whereas impairments such as ASE noise are un-polarized. These techniques realize polarization diversity by making use of OSA’s for ­spectral separation, which requires additional components such as polarization controllers, beam splitters and optical switches. Inline polarimetry is now a viable, simpler option using polarization for high speed real-time ­measurements, thus removing the need for additional components as well as the redundancy for filtering channels that may already be filtered. This white paper discusses the TruePhase IPLM Inline Polarimeter from OFS, which is a cost effective solution that can be easily integrated into electronic circuitry for OSNR ­measurement.

Using the OFS TruePhase® IPLM Inline Polarimeter for PMD Measurement
Jain, A. Mikhailov, V. Westbrook, P.
Abstract: Today, it has become an imperative for fiber-optic network planners to consider physical layer attributes such as dispersion. As network infrastructures increase adoption of 40Gb/s and 100Gb/s solutions, impairments due to dispersion seriously impact the bandwidth capacity of the network as well as the quality of service. Therefore,
characterization and subsequent mitigation of dispersion impairments on a fiber-optic link continue to be critical issues for network operators, especially for fiber segments that are prone to environmental conditions. Presently, there are several techniques, from simply lowering the speed of the fiber to using expensive coherent receivers for electronic compensation, which may only compensate to a certain limit. An alternative solution is to use a small form factor device for real-time, high-speed monitoring of dispersion impairments, which can then be used effectively to make compensative corrections. This white paper discusses the TruePhase IPLM Inline Polarimeter from OFS, which is just such a solution that can be easily integrated to make optical networks much more reliable.

In-Line Polarimeter Using Blazed Fiber Gratings
Westbrook, T. A. Strasser, and T. Erdogan
Abstract: We fabricate highly blazed, polarization-sensitive fiber grating taps and show how these may be used in combination
with a UV-induced fiber waveplate to form a compact, in-fiber polarimeter. We show how the polarimeter may be employed as
a feedback element to control polarization and use the feedback loop to demonstrate the stable, broadband (70 nm) operation of the fiber polarimeter.

Digital Lightpath Label Transcoding for Dual-Polarization QPSK Systems
Mark D. Feuer, Vinay A. Vaishampayan, V. Mikhailov, and P. Westbrook
Abstract: We introduce digital lightpath labeling for DP-QPSK transmission, using novel binary encoding to embed a polarization-shift-keyed subchannel. An integrated inline polarimeter powers a compact label receiver with robust tolerance to polarization rotation in a 40Gb/s demonstration.

In-Line, High Speed Fibre Polarimeter with Large Calibration Bandwidth and Accurate Reference-Free Calibration Procedure
V. Mikhailov, S. Dunn, P. S. Westbrook
Abstract: We demonstrate an integrated HiBi fibre polarimeter with 32nm single calibration bandwidth.

Robust Remote Calibration of Fiber Polarimeters
Vitaly Mikhailov, Steve Dunn, and Paul S. Westbrook
Abstract: We show that a fiber polarimeter can be calibrated in place at a distance of 30km even when the intervening fiber varies in temperature. The calibration accuracy converges after at most 20 random stokes polarizations.

All-Fiber Grating-Based Higher Order Mode Dispersion Compensator for Broad-Band Compensation and 1000-km Transmission at 40 Gb/s
S. Ramachandran, B. Mikkelsen, L.C. Cowsar, M.F. Yan, G. Raybon, L. Boivin, M. Fishteyn, W.A. Reed, P.Wisk, D. Brownlow, R.G. Huff and L. Gruner-Nielsen.
Abstract: We use a novel fiber-grating device to demonstrate the first polarization-insensitive all-fiber higher order mode dispersion compensator for broad-band dispersion compensation. 

Bandwidth Control of Long-Period Gratings-Based Mode Converters in Few-Mode Fibers
Siddharth Ramachandran, Zhiyong Wang and Man yan
Abstract: Control of the group-velocity differences between two distinct modes in a few-mode fiber can be used to define the spectral characteristics of long-period gratings written in them. 

Band-Selection Filters with Concatenated Long-Period Gratings in Few-Mode Fibers
Siddharth Ramachandran, Samir Ghalmi, Zhiyong Wang and Man Yan
Abstract: We demonstrate a novel device that comprises a pair of broadband and narrowband long-period gratings written in specially designed few-mode fibers to achieve in-fiber bandpass filtering. 

Tunable Dispersion Compensators Utilizing Higher Order Mode Fibers
S. Ramachandran, S. Ghalmi, S. Chandrasekhar, I. Ryazansky, M.F. Yan, F.V. Dimarcello, W.A. Reed and P. Wisk
Abstract: We demonstrate a novel tunable dispersion compensator that utilizes higher order mode fibers and switchable fiber gratings. 

Record Bandwidth, Spectrally Flat Coupling with Microbend Gratings in Dispersion-Tailored Fibers
Siddharth Ramachandran, Man F. Yan, Eric Monberg, Frank V. Dimarcello, Patrick Wisk and Samir Ghalmi
Abstract: We demonstrate resonant grating couplers with the broadest bandwidth (565 nm) reported to date, using microbend gratings in dispersion-optimized few-mode fibers. 

Tunable Optical Fiber Devices Based on Broadband Long-Period Gratings and Pumped Microfluidics
Bharat R. Acharya, Tom Krupenkin, Siddharth Ramachandran, Z. Wang, C.C. Huang and John A. Rogers
Abstract: This letter describes classes of tunable microfluidic fiber (µFF) devices that use specially designed long-period gratings in which the phase matching condition is satisfied over a wide spectral range. 

Ultrasensitive Long-Period Fiber Gratings for Broadband Modulators and Sensors
Zhiyong Wang and Siddharth Ramachandran
Abstract: We demonstrate long-period fiber gratings whose attenuation can be changed by 25 dB over a 48-nm spectral band, with ambient-index changes of only 2.7 x 10-4. 

Highly Sensitive Optical Response of Optical Fiber Long Period Gratings to Nanometer-Thick Ionic Self-Assembled Multilayers
Zhiyong Wang, J.R. Heflin, Rogers H. Stolen and Siddharth Ramachandran
Abstract: Ionic self-assembled multilayers deposited on long period fiber gratings (LPGs) yield dramatic resonant-wavelength shifts, even with nanometer-thick films. 

High-Energy (Nanojoule) Femtosecond Pulse Delivery with Record Dispersion Higher-Order Mode Fiber
S. Ramachandran, M.F. Yan, J. Jasapara, P. Wisk, S. Ghalmi, E. Monberg, and F.V. Dimarcello
Abstract: Delivery of high peak-power femtosecond pulses with fibers is constrained by nonlinear distortions accumulated during pulse propagation. 

Probing Optical Microfiber Nonuniformities at Nanoscale
M. Sumetsky, Y. Dulashko, J. M. Fini, A. Hale, and J.W. Nicholson
Abstract: We demonstrate a novel, simple, and comprehensive method for probing optical microfiber surface and bulk distortions with subnanometer accuracy. 

Suppression of Stimulated Raman Scattering in a Cladding Pumped Amplifier
with an Yb-doped Filter Fiber
J.M. Fini, M.D. Mermelstein, M.F. Yan, R.T. Bise, A.D. Yablon, P.W. Wisk, and M.J. Andrejco
Abstract: A cladding-pumped, high-power amplifier was built incorporating a star-shaped, Yb-doped filter fiber. Pulsed amplifier measurements demonstrate strong suppression of stimulated Raman scattering accomplished by a special index profile with an up-doped ring.

Increased Pulsed Amplifier Efficiency by Manipulating the Fiber Dopant Distribution
J.M. Oh, C. Headley, M.J. Andrejco, A.D. Yablon, and D.J. DiGiovanni
Abstract: In the pulse application, a significantly increased efficiency of high power large-mode area fiber amplifiers is demonstated by improving the overlap of the doped region with the fundamental mode of the fiber. 

The Microfiber Loop Resonator: Theory, Experiment and Application
M. Sumetsky, Y. Dulashko, J.M. Fini, A. Hale, and D.J. DiGiovanni
Abstract: This paper describes the theory of a microfiber loop resonator (MLR) and experimentally demonstrates a high quality factor MLR in free space.

Optical and Microwave Frequency Synthesis with an Integrated Fiber Frequency Comb
I. Hartl and M.E. Fermann - IMRA America, Inc.
W. Swann, J. McFerran, I. Coddington, Q. Quraishi, S. Diddams and N. Newbury - National Institute of Standards and Technology
C. Langrock and M.M. Fejer - E.L. Ginzton Laboratory
P.S. Westbrook, J.W. Nicholson, and K.S. Feder - OFS Laboratories
Abstract: In the past several years, the technological maturity of ultrafast lasers as well as supercontinuum generation in nonlinear optical fibers has revolutionized optical frequency metrology. 

Stable Femtosecond Optical Frequency Comb at 1.3 µm
Using Spectrally-Tailored Continuum From a Nonlinear Fiber Grating
K. Kim, L. Hollberg and S.A. Diddams - National Institue of Standards and Technology
P.S. Westbrook, J.W. Nicholson, and K.S. Feder - OFS Laboratories
Abstract: We demonstrate optical coherence over a broad spectral range of two independent fiber frequency combs. Additionally, we deomonstrate microwave stability of better than 2 x 10-14 in 1 second for an optically integrated fiber frequency comb. 

Perturbative Solution to Continuum Generation in Fiber Gratings
P.S. Westbrook, J.W. Nicholson
Abstract: We derive an approximate solution to the nonlinear Schrödinger equation which includes the effects of fiber gratings or other narrow-band spectral features. Our approach allows rapid estimation of grating enhancements from a single waveguide-only simulation. 

Improved Supercontinuum Generation through UV Processing of Highly Nonlinear Fibers
Paul S. Westbrook, Jeffrey W. Nicholson, et. al
Abstract: We demonstrate that UV exposure of highly nonlinear, germano-silicate fibers can significantly broaden the infrared supercontinuum generated by femtosecond pulses in these fibers. Both simulations and measurements of the fiber chromatic dispersion show that UV-induced refractive index changes increase the waveguide dispersion by up to 5 ps/(nm-km) at 1570 nm and shift the dispersion zero by over 100 nm. We examine fibers with a range of UV exposure levels and show that the short wavelength edge of the supercontinuum can be continuously changed by more than 100 nm. We also show that the long wavelength edge is extended beyond that of the unexposed fiber. The resulting continuum spans from 0.85 to 2.6. 

Supercontinuum Generation in a Fiber Grating
P.S. Westbrook, J.W. Nicholson, et. al.
Abstract: We show that supercontinuum generation in a fiber containing a Bragg grating exhibits .103 enhancement near the Bragg resonance wavelength. We also show that the grating dispersion exceeds the waveguide dispersion over a bandwidth far in excess of its photonic band gap. The observed enhancement is consistent with nonlinear Schrodinger equation simulations of the supercontinuum formation that combine grating and waveguide dispersion. 

Dispersion Flattened Highly Non-Linear Fiber
C.G. Joergensen, T. Veng, L. Grüner-Nielsen, Man Yan
Abstract: Using the MCVD process a conventional highly non-linear fiber with numerically small dispersion and low dispersion slope in the 1550 nm range has been developed. Dispersion characteristics and splicing results are presented. 

A High Coherence Supercontinuum Source at 1550 nm
J.W. Nicholson, M.F. Yan, A. Yablon, P. Wisk, J. Fleming, F. DiMarcello, E. Monberg
Abstract: We present a low noise supercontinuum source based on a femtosecond fiber laser. Varying the dispersion along the fiber length generates a flat, symmetrically broadened continuum. No degradation in coherence is observed.

A Fiber-Based, High-Power Supercontinuum Light Source
A.K. Abeeluck, C. Headley
Abstract: High-power supercontinuum generation, based on a highly nonlinear fiber pumped by a continuous-wave Raman fiber laser, is reported. Output powers as high as 3.2 W and bandwidths greater than 544 nm are experimentally demonstrated. 

Pulsed and Continuous-Wave Supercontinuum Generation in Highly Nonlinear, Dispersion-Shifted Fibers
J.W. Nicholson, A.K. Abeeluck, C. Headley, M.F. Yan, C.G. Joergensen
Abstract: Supercontinuum generation in a highly nonlinear, dispersion-shifted fiber at 1550 nm is discussed. Spectrum generation under both pulsed and continuous-wave conditions is considered. With a few meters of highly nonlinear, dispersion-shifted fiber and a femtosecond erbium fiber laser, an octave-spanning supercontinuum is demonstrated. Kilometer lengths of nonlinear fiber pumped by a continuous-wave Raman fiber laser are shown to generate a continuum with a bandwidth greater than 247 nm. A nonlinear Schrodinger-equation model is used to investigate the effect of varying the dispersion on the pulsed continuum and noise effects in the continuous-wave continuum. 

A High-Power, Single-Mode, Erbium-Doped Fiber Amplifier Generating 30 fs Pulses with 160 kW
Peak Power
J.W. Nicholson, A. Yablon
Abstract: We describe generation of 400 mW average-power, highly-chirped picosecond pulses at 46 MHz repetition rate in a single-mode erbium-doped amplifier. The pulses are compressed to 30 fs to 160 kW peak power in standard-single-mode fiber.