Very large effective area singlemode photonic bandgap fibre

A photonic bandgap fibre consisting of a 34 /spl mu/m diameter pure silica core surrounded by a periodic cladding has been modelled and characterised. It guides a robust HE/sub 11/ mode at 1.55 /spl mu/m with a 517 /spl mu/m/sup 2/ effective area and 0.4 dB/m propagation losses.     

1 Watt Er/Yb singlemode superfluorescent optical fibre source

A singlemode superfluorescent Er/Yb optical fibre source is described, capable of generating >1 W of output power. The spectral bandwidth of the source can be varied between 0.5 and 4 nm by filtering     

HFC and PON-FTTH networks using higher SBS threshold singlemode optical fibre

Measurements showing improved RF video transmission are presented over a test-bed which replicates parts of a commercial hybrid fibre-coax (HFC) network using an optical fibre specifically engineered for fibre-to-the-home (FTTH) featuring +3 dB higher stimulated Brillouin scattering (SBS) threshold. Results validate improved system performance and increased reach for use in PON and FTTH architectures     

New mode scrambler for optical fibre measurements

A new design of a mode scrambler for optical fibre measurements is presented. A rotation-splice technique has been used to mix the incoming mode power distribution in the fibre. The device is tested under different launch conditions to check its efficiency to produce a definite mode power distribution. Experimental results are presented.     

Towards high-index glass based monomode holey fibre with large mode area

A high-index (n=1.80) glass based holey fibre was fabricated. The conventional capillary-stacking technique was used to make this fibre characterised by a complicated microstructured cladding. Monomode guidance was observed at 800 nm in this fibre and the effective mode area A/sub eff/ was measured as /spl sim/40 /spl mu/m/sup 2/.     

Annealed optical fibre mode scrambler

A mode scrambler based on an annealed step-index fibre is shown to have reproducible performance and source-launch-alignment insensitivity. Devitrification produces scattering centres in the fibre that distribute light uniformly over both angle and radius. An all-fibre mode scrambler with a 10 cm length and an insertion loss <3.5 dB is demonstrated     

Low-loss singlemode waveguide and fibre bends

A new theoretical strategy for reducing bend loss is presented. It is based on the concept of introducing both depressed and increased index regions into the cladding of planar waveguides on the outside of the bent core. A similar strategy can be applied to optical fibres. In both cases, the bending loss is reduced beyond that achievable with the presence of depressed regions alone in the cladding     

Differential singlemode fibre frequency-modulated continuous-wave Sagnac gyroscope

A differential singlemode fibre frequency-modulated continuous-wave Sagnac gyroscope is described. The gyroscope employs two Y-type fibre-optic directional couplers, two X-type fibre-optic directional couplers and a singlemode fibre coil to construct a time-division-multiplexed unbalanced fibre-optic Sagnac interferometer. The rotation velocity of the fibre coil is determined by measuring the phase difference between the two beat signals. Benefiting from the differential technique, this gyroscope can automatically eliminate the unexpected non-reciprocal phase drift (including the frequency drift of the light source) so that the accuracy and long-term stability can be significantly improved.     

Electrically tunable singlemode fibre Bragg reflective filter

An electrically tunable singlemode fibre Bragg reflective filter (FBR) is demonstrated for the first time by using a large amount of magnetostrictive material in which the fibre is embedded and side-polished. With a reflection bandwidth of ~1.5 nm, the measured tuning range of the FBR filter is 1.3 nm     

Asymmetric robust evanescent coupler on singlemode fibre

A new method for flattening the spectral splitting ratio response of the robust evanescent fused tapered coupler is described; through side-polishing the amalgamate of two fibres that have been circularly pre-fused together, the required asymmetry between the fibres is introduced.     

Record-efficient, resonantly-pumped, Er-doped singlemode fibre amplifier

An 85% optical-to-optical efficient, single-frequency performance of resonantly-pumped (at 1476 nm) Yb-free, Er-doped, singlemode fibre amplifier at 1560 nm is reported. The diffraction-limited, single-frequency amplifier is believed to have the highest optical-to-optical efficiency ever reported for Er-doped fibre amplifiers.     

High spatial resolution optical fibre mode profiling

Near-field scanning optical microscopy is used in emission mode to measure the mode profile of singlemode fibre. Excellent agreement is obtained between the mode profile of a singlemode fibre measured using emission and collection modes and qualitative agreement obtained between measurements made on a multimoded fibre and a simple theoretical model.     

Slow light generation in singlemode er-doped tellurite fibre

The efficient generation of slow light in a singlemode Er-doped tellurite glass fibre, which has a Brillouin gain coefficient about an order of magnitude larger than silica fibre is reported. Pulses of 60 ns width were delayed by 67 ns in a 2 m length of fibre with a pump power of 630 mW. The large Brillouin gain and relatively low loss of tellurite fibre should be useful in the realisation of compact slow light devices operable at a lower pump power.     

Cavity design for highly efficient singlemode laser in Yb-dopeddouble clad fibre

A novel cavity for a Yb-doped clad-pumped silica fibre laser was designed to enhance the lasing efficiency and the pump absorption into the Yb-doped core, and to provide efficient packaging with low pump power leakage for fibres with totally different parameters. From this cavity setup, we obtained a high power singlemode laser over 3.8 W with a sharp line-width and a slope efficiency of 85%     

一种新型超低损耗大有效面光纤的技术研究

采用双包层的波导结构结合纯二氧化硅芯的技术方案,通过包层氟掺杂的设计与芯/包层之间粘度匹配的优化,实现了超低损耗大有效面积ULA-130型G.654.E光纤的制造,然后利用自行搭建的光纤非线性系数测量系统和自主设计的光纤宏弯损耗松绕设备,结合现有技术对ULA-130光纤的各项性能技术指标进行了研究。该光纤在1 550 nm波长的衰减系数为0.159 dB/km,有效面积为133 μm²,非线性系数为1.67×10^-10W^-1。理论计算与技术研究结果表明,该光纤具有优异的衰减系数和非线性性能,适用于大容量、高速率和长距离光通信骨干网传输系统,相对于常规的 G.652.D 光纤,可以显著改善系统的光信噪比,提升系统的传输性能。     

Reflectometric singlemode elliptical-core fibre strain sensor with remote interrogation

A reflectometric singlemode elliptical-core fibre strain sensor is described. The sensor is based on optical frequency-modulated continuous-wave interference and can be used to measure remotely the strain variation of a distant large construction. The advantages of the sensor include high resolution, long dynamic range, long gauge length, and good stability.     

Extruded singlemode, high-nonlinearity, tellurite glass holey fibre

The fabrication of the first singlemode tellurite glass holey fibre produced from an extruded preform is reported. Robust singlemode guidance was observed at 1047 nm in the fabricated small core holey fibre. An effective mode area of 2.6 /spl mu/m/sup 2/ and high effective nonlinearity of 580 W/sup -1/ km/sup -1/ at 1047 nm were predicted. The fibre loss was measured to be 3.5 dB/m at 1050 nm, and 5.8 dB/m at 1550 nm.     

All-fibre temperature sensor based on macro-bend singlemode fibre loop

An all-fibre temperature sensor is proposed based on a macro-bend singlemode fibre loop using a ratiometric power measurement scheme. The sensor has a linear characteristic with temperature at a fixed wavelength and bend radius. A direct linear relationship between the bend loss of the singlemode fibre and temperature is reported for the first time. By measuring the change in bend loss of the system a change in temperature can be measured assuming the system is calibrated. The proposed sensor has a higher temperature resolution than other conventional fibre-optic sensors and also benefits from simplicity.     

Cancelling soliton interaction in singlemode optical fibres

It is shown that interaction forces between two solitons in a circular fibre can be cancelled exactly by means of a reshaping of their envelop and a proper choice of their polarisation and relative phase. The resulting soliton bound state exhibits polarisation rotation at a rate that depends on the initial pulse separation.<>     

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