Polarization-resolved transmission matrices of specialty optical fibers.

Transmission matrix measurements of multimode fibers are now routinely performed in numerous laboratories, enabling control of the electric field at the distal end of the fiber and paving the way for the potential application to ultrathin medical endoscopes with high resolution. The same concepts are applicable to other areas, such as space division multiplexing, targeted power delivery, fiber laser performance, and the general study of the mode coupling properties of the fiber. However, the process of building an experimental setup and developing the supporting code to measure the fiber's transmission matrix remains challenging and time consuming, with full details on experimental design, data collection, and supporting algorithms spread over multiple papers or lacking in detail.

Polarization-maintained propagation of a 2200 μm effective-area higher-order-mode in a bent optical fiber.

We report on the excitation and polarization preserved propagation of a very large effective-area (A ∼ 2240 μm) higher-order-mode in an optical fiber. A laser signal operating in the 1 μm wavelength region is transported in a Bessel-like LP mode over a 10 m long section of the polarization-maintaining higher-order-mode fiber. We observe that the light propagates through the fiber with >10 dB polarization-extinction-ratio as the fiber is coiled into circular loops of 40 cm diameter.

Reconversion of higher-order-mode (HOM) output from cladding-pumped hybrid Yb:HOM fiber amplifier.

We demonstrate operation of a cladding-pumped hybrid ytterbium-doped HOM fiber amplifier and reconversion of the HOM output to Gaussian-like beam by using an axicon based reconversion system. The amplifier was constructed by concatenating single-mode and HOM ytterbium-doped double clad fibers, and was excited by a common multimode pump source. A continuous wave (cw) input signal of 97mW was amplified to 100W at the amplifier output, which yielded a gain of more than 30dB.

Cognitive load associations when utilizing auditory display within image-guided neurosurgery.

Purpose: The combination of data visualization and auditory display (e.g., sonification) has been shown to increase accuracy, and reduce perceived difficulty, within 3D navigation tasks.

Interaction driven enhancement of depth perception in angiographic volumes.

User interaction has the potential to greatly facilitate the exploration and understanding of 3D medical images for diagnosis and treatment. However, in certain specialized environments such as in an operating room (OR), technical and physical constraints such as the need to enforce strict sterility rules, make interaction challenging. In this paper, we propose to facilitate the intraoperative exploration of angiographic volumes by leveraging the motion of a tracked surgical pointer, a tool that is already manipulated by the surgeon when using a navigation system in the OR.

Real-time transmission of 16 Tb/s over 1020km using 200Gb/s CFP2-DCO.

We demonstrate real-time transmission of 16 Tb/s (80x200Gb/s) over 1020km TeraWave ULL fiber with 170km span length using the world's first 200Gb/s CFP2-DCO module with a record low power consumption less than 0.1W/Gbps.

Polarization-maintaining, large-effective-area, higher-order-mode fiber.

Higher-order-mode (HOM) fibers guiding light in large-effective-area (A) Bessel-like modes have recently generated great interest for high-power laser applications. A polarization-maintaining (PM) version of HOM fibers can afford the added possibility of coherent beam combination, improved material processing, and polarization multiplexing of high-power fiber lasers. We report a PM-HOM fiber for guiding Bessel-like modes with A ranging from 1200-2800  μm.

800Gb/s (8x128Gb/s) unrepeatered transmission over 515-km large-area ultra-low-loss fiber using 2nd-order Raman pumping.

We demonstrate unrepeatered transmission of 8x128Gb/s PDM-QPSK signals over a 515k-m fiber link. This ultra-long distance of 800 Gb/s unrepeatered transmission in a single fiber configuration is achieved by employing enabling techniques such as large-effective-area ultra-low-attenuation fibers, co-propagating and counter-propagating 2nd-order-pumped distributed Raman amplification, and remote optically pumped amplifier (ROPA). The ROPA itself is also counter-propagating 2nd-order Raman pumped.

DYNAMIC SONOGRAPHY OF THE EQUINE METACARPO(TARSO)PHALANGEAL DIGITAL FLEXOR TENDON SHEATH.

Palmar/plantar annular desmitis is a common disease that may be associated with adhesions and structures affecting the flexor tendons, which requires tenoscopy to diagnose. The purpose of this descriptive study was to develop a dynamic sonographic technique for evaluating the motion of normal equine flexor tendons in relation to the palmar/plantar annular ligament and to compare findings with horses previously diagnosed with palmar/plantar annular desmitis. Ten healthy adult horses were examined prospectively and the images of four horses diagnosed with palmar/plantar annular desmitis were retrospectively evaluated.

Long-term outcomes of 176 patients with X-linked hyper-IgM syndrome treated with or without hematopoietic cell transplantation.

Background: X-linked hyper-IgM syndrome (XHIGM) is a primary immunodeficiency with high morbidity and mortality compared with those seen in healthy subjects. Hematopoietic cell transplantation (HCT) has been considered a curative therapy, but the procedure has inherent complications and might not be available for all patients.

Objectives: We sought to collect data on the clinical presentation, treatment, and follow-up of a large sample of patients with XHIGM to (1) compare long-term overall survival and general well-being of patients treated with or without HCT along with clinical factors associated with mortality and (2) summarize clinical practice and risk factors in the subgroup of patients treated with HCT.

Axicons for mode conversion in high peak power, higher-order mode, fiber amplifiers.

Higher-order mode fiber amplifiers have demonstrated effective areas as large as 6000 μm2, allowing for high pulse energy and peak power amplification. Long-period gratings are used to convert the fundamental mode to the higher-order mode at the entrance to the amplifier, and reconvert back to the fundamental at the exit, to achieve a diffraction limited beam. However, long period gratings are susceptible to nonlinearity at high peak power.

Endoscopic, transoral, reduction of epiglottic entrapment via wire snare technique.

Objective: To describe the use of a wire snare technique for epiglottic entrapment.

Study Design: Case series.

Animals: Eight adult horses.

Seven-core erbium-doped double-clad fiber amplifier pumped simultaneously by side-coupled multimode fiber.

We demonstrate a seven-core erbium-doped fiber amplifier in which all the cores were pumped simultaneously by a side-coupled tapered multimode fiber. The amplifier has multicore (MC) MC inputs and MC outputs, which can be readily spliced to MC transmission fiber for amplifying space division multiplexed signals. Gain over 25 dB was obtained in each of the cores over a 40-nm bandwidth covering the C-band.

Higher-order mode fiber enables high energy chirped-pulse amplification.

Energy scaling of femtosecond fiber lasers has been constrained by nonlinear impairments and optical fiber damage. Reducing the optical irradiance inside the fiber by increasing mode size lowers these effects. Using an erbium-doped higher-order mode fiber with 6000 µm(2) effective area and output fundamental mode re-conversion, we show a breakthrough in pulse energy from a monolithic fiber chirped pulse amplification system using higher-order mode propagation generating 300 µJ pulses with duration <500 fs (FWHM) and peak power >600 MW at 1.

High-power broadband Yb-free clad-pumped EDFA for L-band DWDM applications.

We demonstrated high-power broadband Yb-free clad-pumped erbium-doped fiber amplifier (EDFA) using commercial available low-cost 976 nm multimode diodes. An output power +33 dBm with less than ±1 dB natural gain flatness over a gain bandwidth of 33 nm (1570.3-1603.

Scaling the effective area of higher-order-mode erbium-doped fiber amplifiers.

We demonstrate scaling of the effective area of higher-order mode, Er-doped fiber amplifiers. Two Er-doped higher-order mode fibers, one with 3800 μm(2) A(eff) in the LP(0,11) mode, and one with 6000 μm(2) effective area in the LP(0,14) mode, are demonstrated. Output beam profiles show clean higher order modes, and S(2) imaging measurements show low extraneous higher order mode content.

Scrambled coherent superposition for enhanced optical fiber communication in the nonlinear transmission regime.

Coherent superposition of light waves has long been used in various fields of science, and recent advances in digital coherent detection and space-division multiplexing have enabled the coherent superposition of information-carrying optical signals to achieve better communication fidelity on amplified-spontaneous-noise limited communication links. However, fiber nonlinearity introduces highly correlated distortions on identical signals and diminishes the benefit of coherent superposition in nonlinear transmission regime. Here we experimentally demonstrate that through coordinated scrambling of signal constellations at the transmitter, together with appropriate unscrambling at the receiver, the full benefit of coherent superposition is retained in the nonlinear transmission regime of a space-diversity fiber link based on an innovatively engineered multi-core fiber.

Cladding-pumped erbium-doped multicore fiber amplifier.

A cladding pumped multicore erbium-doped fiber amplifier for simultaneous amplification of 6 channels is demonstrated. Peak gain over 32 dB has been obtained at a wavelength of 1560 nm and the bandwidth measured at 20-dB gain was about 35 nm. Numerical modeling of cladding pumped multicore erbium-doped amplifier was also performed to study the properties of the amplifier.

Photo-induced SNAP: fabrication, trimming, and tuning of microresonator chains.

We introduce multiple series of uncoupled and coupled surface nanoscale axial photonics (SNAP) microresonators along the 30 micron diameter germanium-doped photosensitive silica optical fiber and demonstrate their permanent trimming and temporary tuning with a CO2 laser and a wire heater. Hydrogen loading allows us to increase the introduced variation of the effective fiber radius by an order of magnitude compared to the unloaded case, i.e.

Coupled high Q-factor surface nanoscale axial photonics (SNAP) microresonators.

We experimentally demonstrate series of identical two, three, and five coupled high Q-factor surface nanoscale axial photonics (SNAP) microresonators formed by periodic nanoscale variation of the optical fiber radius. These microresonators are fabricated with a 100 μm period along an 18 μm radius optical fiber. The axial FWHM of these microresonators is 80 μm and their Q-factor exceeds 10(7).

Surface nanoscale axial photonics: robust fabrication of high-quality-factor microresonators.

Recently introduced surface nanoscale axial photonics (SNAP) makes it possible to fabricate high-Q-factor microresonators and other photonic microdevices by dramatically small deformation of the optical fiber surface. To become a practical and robust technology, the SNAP platform requires methods enabling reproducible modification of the optical fiber radius at nanoscale. In this Letter, we demonstrate superaccurate fabrication of high-Q-factor microresonators by nanoscale modification of the optical fiber radius and refractive index using CO2 laser and UV excimer laser beam exposures.

Raman fiber laser with 81 W output power at 1480 nm.

We demonstrate a Raman fiber laser with an operating wavelength of 1480 nm and record output power of 81 W. High-power operation is enabled by a long-period grating used to frustrate backward lasing at the Stokes wavelength in the Yb-doped fiber amplifier. A cascaded Raman fiber with a long-wavelength fundamental mode cutoff enables efficient multiple Stokes scattering from 1117 to 1480 nm while preventing further unwanted scattering to 1590 nm.

A higher-order-mode erbium-doped-fiber amplifier.

We demonstrate the first erbium-doped fiber amplifier operating in a single, large-mode area, higher-order mode. A high-power, fundamental-mode, Raman fiber laser operating at 1480 nm was used as a pump source. Using a UV-written, long-period grating, both pump and 1564 nm signal were converted to the LP(0,10) mode, which had an effective area of 2700 microm(2) at 1550 nm.

Ultraviolet photosensitive response in an antimony-doped optical fiber.

A silica optical fiber doped with Sb is fabricated with a refractive-index profile that is comparable with standard single-mode fiber. In D(2)-loaded samples, we observe UV photosensitivity with an initial refractive-index-modulation growth rate six times higher than that of the equivalent Ge-doped standard fibers. Enhanced temperature stability of the Bragg grating strength up to 200 degrees C is also observed.