Extruded singlemode non-silica glass holey optical fibres

The fabrication of the first microstructured singlemode non-silica optical fibre is reported. Extrusion has been used for the first time to produce the microstructured fibre preform. The final drawn fibre has an effectively air-suspended 2 μm core. Singlemode guidance is observed from 633-1500 nm     

Bidirectional optical transmission using polarised light waves

Bidirectional optical transmission using polarised light waves is demonstrated for the first time. Transmission of 100 Mbit/s signals over 13.6 km of polarisation-maintaining fibre occurs simultaneously in both directions at 1.55/?m. LD transmitters with polarisation-maintaining fibre pigtails, polarisation-maintaining fibre couplers, fibre polarisers and Ge-APD receivers are used.     

Experimental demonstration of step-like dispersion profiling inoptical fibre for soliton pulse generation and compression

Generation of 100 GHz trains of 500-700 fs pulses using dual-frequency beat conversion in a step-like dispersion profiled fibre is reported. The authors believe that this is the first time the generation and compression of soliton pulses using such a fibre has been demonstrated. The fabrication of such fibre assemblies does not require any special facilities and relies only on conventional optical fibre technology. They believe that the use of profiling the fibre dispersion by fibre segments instead of continuously dispersion-decreasing fibre is not only possible but preferable in many applications     

Structural and optical characterisation of holey fibres usingscanning probe microscopy

An investigation of a holey fibre using scanning probe microscopy techniques, which the authors believe is the first such investigation, is presented. Atomic force microscopy images provide knowledge of the fibre structure without the artefacts associated with scanning electron microscopy imaging. A tapered fibre scanning near-field optical microscopy probe has been used to investigate holey fibre modes at 785 nm     

Installation of dispersion-shifted fibre in the British Telecomtrunk network

Measurements are presented from the first installation of dispersion-shifted fibre into the British Telecom network. The cabled fibre performance is compared to that obtained in laboratory trials and analysed with respect to the fibre structure before and after installation     

80 Gbit/s pulsewidth-maintained wavelength conversion based on HNLDSF-NOLM including transmission over 80 km of conventional SMF

80 Gbit/s pulsewidth-maintained wavelength conversion based on a high-nonlinearity dispersion shifted fibre nonlinear optical loop mirror (DSF-NOLM) is realised and penalty-free transmission over 80 km conventional single mode fibre and 12 km dispersion compensating fibre of the converted signal is demonstrated for the first time     

Vector bending sensors based on fibre Bragg gratings inscribed by infrared femtosecond laser

A direction-sensitive bend sensor in standard singlemode fibre is demonstrated for the first time based on an axially-offset fibre Bragg grating, directly written by an infrared femtosecond laser.     

Wideband gain flattened erbium fibre amplifier using a photosensitive fibre blazed grating

An erbium fibre amplifier with a highly flattened gain spectrum is demonstrated for the first time using an all fibre photosensitive Bragg grating. An ASE spectrum flattened to within +or-0.5 dB over a bandwidth of 35 nm in the 1550 nm window is achieved with a 3 mm long radiation coupling Bragg fibre grating.<>     

Chalcogenide holey fibres

The fabrication of the first non-silica holey or microstructured optical fibre is reported. The chalcogenide glass gallium lanthanum sulphide was used. Applications of such fibres include optical switching, high power-delivery, acousto-optic devices, air-guiding fibres, fibre sensors, mid-IR devices, amongst others. In addition, holey fibre technology provides an improved route towards fabricating singlemode compound glass fibres     

Yb3+-doped photonic crystal fibre laser

An ytterbium doped core has been incorporated into a photonic crystal fibre (PCF) with anomalous group velocity dispersion at all wavelengths longer than 730 nm. Laser action is observed for the first time in such a fibre. This demonstration of lasing in PCF is a vital step towards realising the huge potential of PCF for fibre laser applications     

2.4 Gbit/s 100 km penalty-free conventional fibre transmission experiments using GaInAsP electroabsorption modulator

The superior characteristics of a semiconductor modulator for a multi-Gbit/s and long-haul fibre transmission are confirmed for the first time. A 2.4 Gbit/s over 100 km conventional single-mode fibre transmission has been successfully achieved by using a GaInAsP electroabsorption modulator. No power penalty was observed even under 1700 ps/nm chromatic fibre dispersion.<>     

Fibre backbone for cable TV using multi-channel am video trunking

This paper updates a scenario for the evolutionary integration of optical fibre transmission technology into existing cable television networks first presented in 1988. The resulting ‘fibre backbone’ yields a hybrid fibre/coaxial network with significantly better reliability and transmission quality than present systems. System and electro-optical component advances in the last year are reviewed, and the merits of various modulation techniques are examined. The fibre backbone approach emphasizes continuing the broadband delivery of a large number of video signals to the consumer.     

Single-mode-fibre passive components made in the fused-head-end technique

The fused-head-end technique, used successfully until now for producing passive fibre components in multimode fibre, can also be applied to produce single-mode fibre couplers and splitters. The device is based on evanescent mode coupling and has no pigtail problem. The first experimental results are presented, together with the theoretical interpretation. Some expected system applications and further improvements are indicated.     

γ-radiation-induced attenuation in photonic crystal fibre

Results are presented of what, to the knowledge of the authors, is the first study of the sensitivity of a photonic crystal fibre (PCF) under steady-state gamma irradiation. Radiation-induced attenuation of a PCF has been measured at 1.55 μm. This new type of fibre showed a higher attenuation level than a standard monomode fibre but had a fast kinetic of recovery after irradiation     

Measurement of intermodal coupling in weakly multimode fibre optics

Using selective mode excitation via the cladding of an etched step-index weakly multimode fibre, and spatial mode separation at the output using a similarly etched section, intermodal coupling has been measured, mode-by-mode in the first seven guided modes of the fibre. Experimentally the observation has been made that most coupling terms remain less than -20 dB after 500 m of fibre.<>     

玉米粗纤维含量高光谱估算模型研究

以不同品种玉米叶片、茎、穗和叶鞘的室内光谱反射率及对应的粗纤维含量为数据源,通过相关性分析发现原始光谱以及一阶导数光谱粗纤维含量光谱诊断的敏感波段分别位于近红外波段的1924nm和2370nm;线性与非线性拟合分析表明以2370nm处的一阶导数光谱所构建的线性模型相对其它模型最优,模型RMSE=3.538,由此模型得到的粗纤维含量理论值与实测值之间极显著相关,相关系数r=0.693.     

Modelocked laser based on ytterbium doped holey fibre

The authors report the fabrication of a polarisation-maintaining, high-nonlinearity, anomalously dispersive, Yb³⁺ doped holey fibre and describe what they believe to be the first demonstration of a modelocked holey fibre laser     

Single pulse Bragg gratings written during fibre drawing

For the first time the production of Bragg fibre gratings written by single excimer laser pulses as the fibre is being drawn is demonstrated. Reflectivities approaching 100% have been obtained, demonstrating the feasibility of online mass production.<>     

Efficient silica-based Ho3+ fibre laser for 2 μmspectral region pumped at 1.15 μm

For the first time an Ho³⁺ silica fibre laser has been realised using a Bragg grating as the input coupler and a fibre pump source at 1.15 μm. The output power of 280 mW at 2 μm is to the authors' knowledge the highest value reported so far for Ho³⁺ silica fibre lasers     

Photosensitivity in low-loss perfluoropolymer (CYTOP) fibrematerial

Photosensitivity in a perfluoropolymer (CYTOP) optical fibre is investigated. Significant diffraction has been observed from transmission gratings made from the fibre. A maximum diffraction efficiency of 1.6% has been achieved, corresponding to an index change ≃3×10^-4. The study demonstrates for the first time the existence of significant photosensitivity and the feasibility of writing a Bragg grating in a CYTOP fibre