Multi-core anti-resonant hollow core optical fiber.

We report the fabrication and characterization of a multi-core anti-resonant hollow core fiber with low inter-core coupling. The optical losses were 0.03 and 0.

Low-loss, compact, fibre-integrated cell for quantum memories.

We present a low-loss, compact, hollow core optical fibre (HCF) cell integrated with single mode fibre (SMF). The cell is designed to be filled with atomic vapour and used as a component in photonic quantum technologies, with applications in quantum memory and optical switching. We achieve a total insertion loss of 0.

Ultra-low threshold deep ultraviolet generation in a hollow-core fiber.

Tunable ultrashort pulses in the ultraviolet spectral region are in great demand for a wide range of applications, including spectroscopy and pump-probe experiments. While laser sources capable of producing such pulses exist, they are typically very complex. Notably, resonant dispersive-wave (RDW) emission has emerged as a simple technique for generating such pulses.

Guidance of ultraviolet light down to 190 nm in a hollow-core optical fibre.

We report an anti-resonant hollow core fibre with ultraviolet transmission down to 190 nm, covering the entire UV-A, UV-B and much of the UV-C band. Guidance from 190 - 400 nm is achieved apart for a narrow high loss resonance band at 245 - 265 nm. The minimum attenuation is 0.

Axi-Stack: a method for manufacturing freeform air-silica optical fibre.

We present a method with potential for fabricating freeform air-silica optical fibre preforms which is free from the stacking constraints associated with conventional stack-and-draw. The method, termed Axi-Stack, is enabled by the precision machining of short cross-sectional preform discs by ultrafast laser assisted etching; a laser-based microfabrication technique which facilitates near arbitrary shaping of the preform structure. Several preform discs are stacked axially and fused together via ultrafast laser welding to construct the preform, which can be drawn to fibre using conventional methods.

Measurement of resonant bend loss in anti-resonant hollow core optical fiber: erratum.

An error on the part of the authors in drafting resulted in Eq. (3) being incorrect in the published paper [Opt. Express25, 20612 (2017)10.

Stack, seal, evacuate, draw: a method for drawing hollow-core fiber stacks under positive and negative pressure.

The two-stage stack and draw technique is an established method for fabricating microstructured fibers, including hollow-core fibers. A stack of glass elements of around a meter in length and centimeters in outer diameter forms the first stage preform, which is drawn into millimeter scale canes. The second stage preform is one of the canes, which is drawn, under active pressure, into microscopic fiber.

3D-M3: high-spatial-resolution spectroscopy with extreme AO and 3D-printed micro-lenslets.

By combining integral field spectroscopy with extreme adaptive optics, we are now able to resolve objects close to the diffraction limit of large telescopes, exploring new science cases. We introduce an integral field unit designed to couple light with a minimal plate scale from the SCExAO facility at NIR wavelengths to a single-mode spectrograph. The integral field unit has a 3D-printed micro-lens array on top of a custom single-mode multi-core fiber, to optimize the coupling of light into the fiber cores.

Computational optical imaging with a photonic lantern.

The thin and flexible nature of optical fibres often makes them the ideal technology to view biological processes in-vivo, but current microendoscopic approaches are limited in spatial resolution. Here, we demonstrate a route to high resolution microendoscopy using a multicore fibre (MCF) with an adiabatic multimode-to-single-mode "photonic lantern" transition formed at the distal end by tapering. We show that distinct multimode patterns of light can be projected from the output of the lantern by individually exciting the single-mode MCF cores, and that these patterns are highly stable to fibre movement.

Molecular detection of Gram-positive bacteria in the human lung through an optical fiber-based endoscope.

Purpose: The relentless rise in antimicrobial resistance is a major societal challenge and requires, as part of its solution, a better understanding of bacterial colonization and infection. To facilitate this, we developed a highly efficient no-wash red optical molecular imaging agent that enables the rapid, selective, and specific visualization of Gram-positive bacteria through a bespoke optical fiber-based delivery/imaging endoscopic device.

Methods: We rationally designed a no-wash, red, Gram-positive-specific molecular imaging agent (Merocy-Van) based on vancomycin and an environmental merocyanine dye.

Adiabatic higher-order mode microfibers based on a logarithmic index profile.

Optical fibers with a logarithmic index profile can provide invariant mode field diameters along a tapered fiber, which enables adiabatic mode transitions for higher-order mode (HOM) microfibers. A microfiber with a waist diameter of ∼2 µm is fabricated with an insertion loss lower than 0.03 dB for the LP and 0.

Observation of Rapid Adiabatic Passage in Optical Four-Wave Mixing.

We observe clear evidence of adiabatic passage between photon populations via a four-wave mixing process, implemented through a dispersion sweep arranged by a core diameter taper of an optical fiber. Photonic rapid adiabatic passage through the cubic electric susceptibility thus opens precise control of frequency translation between broadband light fields to all common optical media. Areas of potential impact include optical fiber and on-chip waveguide platforms for quantum information, ultrafast spectroscopy and metrology, and extreme light-matter interaction science.

High-resolution air-clad imaging fibers.

We present a coherent fiber bundle comprising over 11,000 doped silica cores separated by an air-filled cladding. The fiber is characterized, and its imaging quality is shown to be a substantial improvement over the commercial state of the art, with comparable resolution over an unparalleled spectral range.

Ultra-low background Raman sensing using a negative-curvature fibre and no distal optics.

Measuring Raman spectra through an optical fibre is usually complicated by the high intrinsic Raman scatter of the fibre material. Common solutions such as the use of multiple fibres and distal optics are complex and bulky. We demonstrate the use of single novel hollow-core negative-curvature fibres (NCFs) for Raman and surface-enhanced Raman spectroscopy (SERS) sensing using no distal optics.

Quantitative characterization of endoscopic imaging fibers.

We describe a technique for the quantitative characterization of endoscopic imaging fibers using an interference pattern as the standard object to be imaged. The visibility of the pattern at the other end of the fiber is then analyzed as wavelength and fringe period are varied. We demonstrate the use of the technique by comparing three fibers: two fabricated in-house from the same preform, designed to minimize inter-core coupling at visible wavelengths less than 650 nm, and a commercial imaging fiber.

All-fibre pseudo-slit reformatters.

We report two different types of all-fibre pseudo-slit reformatters made either by tapering bundles of single-mode fibres or by postprocessing a photonic crystal fibre. These devices convert the modes of a multimode core to the modes of a linear pseudo-slit output structure, achieving a diffraction limited pattern in one direction.

Divide and conquer: an efficient solution to highly multimoded photonic lanterns from multicore fibres.

Photonic lanterns typically allow for single-mode action in a multimode fibre. Since their invention over a decade ago for applications in astrophotonics, they have found important uses in diverse fields of applied science. To date, large aperture highly-mulitmoded to single-mode lanterns have been difficult as fabrication techniques are not practical for mass replication.

Low index contrast imaging fibers.

We present high-resolution imaging fibers made from low-cost commercially available fiber preforms manufactured for the telecommunications industry. Our fabrication method involves multi-stacking arrays of different sized cores in order to suppress core-to-core crosstalk whilst building up a large array of cores. One of the fibers, based on a square array of cores, has comparable imaging performance to commercial imaging fibers but without the need for exceptionally high refractive index contrasts, and will enable the development of economically viable single-use disposable imaging fibers.

Multiplexed single-mode wavelength-to-time mapping of multimode light.

When an optical pulse propagates along an optical fibre, different wavelengths travel at different group velocities. As a result, wavelength information is converted into arrival-time information, a process known as wavelength-to-time mapping. This phenomenon is most cleanly observed using a single-mode fibre transmission line, where spatial mode dispersion is not present, but the use of such fibres restricts possible applications.

Endoscopic sensing of alveolar pH.

Previously unobtainable measurements of alveolar pH were obtained using an endoscope-deployable optrode. The pH sensing was achieved using functionalized gold nanoshell sensors and surface enhanced Raman spectroscopy (SERS). The optrode consisted of an asymmetric dual-core optical fiber designed for spatially separating the optical pump delivery and signal collection, in order to circumvent the unwanted Raman signal generated within the fiber.

Missed adolescent acetabular apophyseal avulsion with late hip dislocation.

Background: Chronic hip dislocation associated with acetabular apophyseal avulsion in adolescence is rare. Whilst superior acetabular rim fractures have a documented theoretical risk of hip instability, we have not found a case of chronic dislocation resulting from this.

Methods: We report a case of a 12-year-old healthy boy who initially sustained a missed right acetabular apophyseal avulsion after falling from a quad bike.

Meta-analysis of warmed versus standard temperature CO2 insufflation for laparoscopic cholecystectomy.

Background: There is conflicting evidence for the use of warmed, humidified carbon dioxide (CO2) for creating pneumoperitoneum during laparoscopic cholecystectomy. Few studies have reported less post-operative pain and analgesic requirement when warmed CO2 was used.

Aim: This systematic review and meta-analysis aims to analyse the literature on the use of warmed CO2 in comparison to standard temperature CO2 during laparoscopic cholecystectomy.