1,721,318 research outputs found
Dataset for All-fiber fourth and fifth harmonic generation from a single source
No full textRaw data for figures in Abdul Khudus, Muhammad, Lee, Timothy, De Lucia, Francesco, Corbari, Constantino, Sazio, Pier-John, Horak, Peter and Brambilla, Gilberto (2016) All-fiber fourth and fifth harmonic generation from a single source. Optics Express, 24, (19), 21777-21793. (doi:10.1364/OE.24.021777)</span
Optical fibres: From telecom to manufacturing and beyond
No full textOptical fibres constitute the internet physical backbone and have wired up the whole globe, with a total cumulative length exceeding a billion km. Although optical fibres have experienced an extraordinary success in telecommunications, they have also found a multitude of applications in a variety of fields, ranging from distributed sensing to high power lasers and manufacturing.This talk will overview optical fibres with a focus on recent applications.<br/
An investigation of the physical properties and fabrication techniques of novel glasses and waveguides with enhanced photosensitivity
No full textIn 1978 an experiment showed that 488 nm laser radiation can induce self-written refractive index gratings in optical fibres when launched into the core. No real excitement pervaded the scientific community until efficient side-writing was shown in 1989. In contrast to self-written gratings that only operate at the writing wavelength, side-written gratings can have any periodicity longer than the writing wavelength. Driven by the many important applications in telecom and sensor fields, great progress has since been made both in the writing-technology and in the research for new photosensitive materials. This thesis describes the work carried out at the University of Southampton to develop new materials and post-fabrication techniques for enhanced photosensitivity and to understand the basic mechanisms behind such a phenomenon. A low-loss, highly-photosensitive and telecom-compatible fibre has been fabricated by using tin as the only dopant of silica. Its physical mechanism was studied and a model was proposed to explain the results. A conventional post-fabrication method (hydrogen loading), used to improve photosensitivity, showed that gratings written in tin-doped fibres exhibit extraordinarily high thermal stability. Photosensitive fibres for high-temperature sensing were also developed; gratings written with a 248 nm laser were shown to survive for 30 minutes at a record temperature of 850ºC. Finally the development of a post-fabrication technique to increase the photosensitivity was tested on many fibres and a possible explanation of its physical mechanism was found
Room-temperature watt-level and tunable ∼3 µm lasers in Ho<sup>3+</sup>/Pr<sup>3+</sup> co-doped AlF<sub>3</sub>-based glass fiber
No full textA room-temperature watt-level continuous-wave-output power mid-infrared fiber laser operating at λ ∼ 3 µm is demonstrated using a Ho
3
+ /Pr
3
+ co-doped AlF
3 based glass fiber as a gain fiber. This fixed-wavelength laser had maximum output power of 1.13 W with a slope efficiency of 10.3% and a long-term operating stability of >40 min without any additional packaging or active thermal management. A fiber laser with tunability from 2.842 to 2.938 µm showed a maximum output power of 110 mW.
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Specialty optical fibres and devices for the internet of things
No full textMulticore fibers, coherent communications, polarization and modal multiplexing have been recently proposed to address the perceived lack of data transmission capacity in optical fiber communication systems [1]. While fibers, and amplifiers have been promptly developed in mode division multiplexing (MDM), add/drop multiplexing still represents a challenge. Here a weakly-fused microfiber coupler manufactured from a single mode fiber (SMF) and a few-mode fiber (FMF) allows for the efficient multiplexing of a high order mode in the FMF from a fundamental mode at the SMF input. Unlike conventional couplers, which are manufactured at high temperature and thus exhibit a circular cross section, intermodal couplers are manufactured at low temperature allowing for the tackling of the two microfibers without any circularization. Because of the circular geometry of the microfibers composing the coupler, the modes propagating in the two microfibers have a profile extremely similar to those of single microfibers in isolation and coupling between the SMF fundamental mode and the FMF high order mode is simply achieved by matching the propagation constants of the modes propagating in the two fibers [2]. When microfibers have a size smaller than 10µm, modes are guided by the silica/air interface and the modal effective index is determined by the microfiber diameter. Because of the larger overlap with the surrounding lower refractive index cladding, higher order modes have a lower effective index, thus matching the propagation constants of different modes in different microfibers can be achieved by using different microfiber diameters, i.e. with asymmetric coupler cross sections. In the coupler uniform waist region, coupling mostly occurs between the mode propagating in the SMF microfiber and the mode with closest propagation constant in the FMF microfiber, as the coupling strength between different modes is inversely proportional to the mismatch between the mode propagation constants.Intermodal optical fibre couplers were fabricated using the modified flame brushing technique [3]. The SMF was a commercially available telecom fiber with cut-off at lambda=1.25µm, while the FMF consisted of a four-mode fiber with outer diameter of OD=125µm. The ratio between the microfibers was obtained from the eigenvalues of the propagation equation for a silica strand in air, assuming that the modes had the same modal effective index in the coupling region. The device length was optimized to have complete power transfer. The average insertion loss recorded in the couplers was of the order of 0.1dB. The spectral purity has been evaluated using CCD cameras by comparing intensity levels between the maximum and the center of the mode, confirming that for higher order modes coupling in excess of 96% have been achieved
Short wavelength generation using sub-micrometre diameter optical fibres
No full textLight generation at short wavelengths, particularly in the UV spectral range, has numerous potential applications, such as biomedical, lithography and undersea communications. To date, this has been achieved using excimer lasers like KrF or XeCl, expensive diodes or near-IR lasers with nonlinear crystals, which suffer from poor beam shapes, relatively complicated optics and relatively low power. Recently, intermodal third harmonic generation in sub-wavelength optical fibres has been proposed to generate light at short wavelengths from near IR laser sources. However, conversion efficiencies have been limited to 10-3 because of the intrinsic surface waves frozen in all amorphous materials during the glass-making process. Here, light at short wavelengths have been generated in optical fibres using the intermodal four wave mixing (FWM) in tapered optical fibres with sub-micrometer diameter
Next-generation fibers: optical fibres go nano
No full textThe manufacture of nanowires from optical fibers provides the longest, most uniform and robust nanowires. Most important, the low optical loss associated to small surface roughness and high homogeneity allows the use of nanowires for optical applications and opens the way to a host of new optical devices for communications, sensing, biology and chemistry. Additionally, optical fiber nanowires are fabricated by adiabatically stretching optical fibers and thus preserve the original optical fiber dimensions at their input and output allowing ready splicing to standard fibers and fiber components. These fiber pigtails have macroscopic dimensions and allow the manipulation of a single nanowire without the expensive instrumentation typical of the nano-world
Optical microfibre devices
No full textIn the last decade optical fibre tapers with micrometer diameter (often called microfibers) have been investigated for numerous applications ranging from sensing to wavelength convertors, telecom and optical manipulation. This paper reviews the various applications of microfibres
Enhanced 3.9 µm emission from diode pumped Ho<sup>3+</sup>/Eu<sup>3+</sup> codoped fluoroindate glasses
No full textThe use of Eu3+ codoping for enhancing the Ho3+: 5I5 → 5I6 emission in fluoroindate glasses shows that Eu3+ could depopulate the lower laser state Ho3+: 5I6 while having little effect on the upper state Ho3+: 5I5, resulting in greater population inversion. The Ho3+/Eu3+ co-doped glass has high spontaneous transition probability (6.31 s−1) together with large emission cross section (7.68 ×10–21 cm2). This study indicates that codoping of Ho3+ with Eu3+ is a feasible alternative to quench the lower energy level of the 3.9 μm emission and the Ho3+/Eu3+ co-doped fluoroindate glass is a promising material for efficient 3.9 μm fiber lasers
Optical fibre nanotaper sensors
No full textThis paper reviews the work carried out in the recent years on sensors which exploit optical fibre nanotapers (OFN). After a brief introduction on the morphology, fabrication and properties of OFN, this paper will review the various OFN sensors. This type of sensors are extremely compact and relatively robust, are usually unperturbed by electromagnetic interference and can be interrogated remotely. In this review sensors will be grouped in three categories according to their morphology: linear sensors, resonant sensors and tip sensors. While linear and resonant sensors exploit the fraction of power propagating in the evanescent field (outside the nanotaper physical boundary), tip sensors exploit light confined within the nanotaper to excite/detect variations within a very limited area
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