Effects of hydrogen diffusion on optical fibre loss increase

The time dependence of fibre loss increase due to hydrogen diffusion for different pressures and temperatures is reported. It is found that the optical fibre loss increases with increasing hydrogen pressure as well as temperature, and decreases with increasing temperature when removed from the hydrogen environment.     

Wavelength-dependent optical loss increase in graded-index optical fibre transmission lines

Wavelength-dependent optical loss increase in GeO2-P2O5-doped graded-index optical fibre transmission lines has been observed. The loss increase is found to depend strongly on the P2O5 concentration. By reducing the P2O5 concentration, loss increases at 1.3 ?m can be suppressed to a sufficient extent without any hindrance for practical usage.     

Infra-red optical loss increase for silica fibre in cable filled with water

Loss increase characteristics of optical fibre in cable filled with water are reported. Drastic loss increase around 1.24 ?m is observed for both graded-index and single-mode fibres. The origin of the loss increase is found to be due to hydrogen gas diffused into the silica glass interstitially.     

Optical loss increase in optical fibre coated with silicone resin containing Si?D

One possible origin of the loss increase phenomenon with heat treatment at 200°C (H2 evolution from the coating material) has been investigated, using optical fibre coated with silicone resin containing the Si?D group. Although OH absorption at 1.4 ?m increases with 200°C heat treatment, no OD peak is observed. It is suggested that silicone resin containing no Si?H and Si?CH2?CH2?Si groups is appropriate as a coating material as no H2 evolution is present.     

Stress and temperature effects on optical loss increase for phosphor-doped silica fibre in the long wavelength region

Irreversible loss increase in the long-wavelength region is first observed for phosphor-doped silica fibres with silicone resin layer by applying the stress at high temperature. The loss increment becomes larger for longer wavelengths. Experimental results show that the loss increase is strongly dependent on stress and temperature.     

The influence of a fibre structure on optical loss in a graded-index fibre

For designing a fibre structure, the influence of structural parameters on optical loss is investigated experimentally for a graded-index fibre. The fibre with large cladding/outer-layer index difference and small cladding thickness is found to have large excess loss near excitation points, such as a launching point and a splicing point.     

Hydraulic pressure dependence of optical loss in jacketed optical fibre

Hydraulic pressure dependence of fibre loss is examined for several jacket structures. It is found that a liquid-filled pipe structure exhibits small loss increase, 0.9 dB/km at a pressure of 500 kg/cm2, and is promising for use in a submarine optical cable     

Transmission loss of UV-curable silicone-coated optical fibre

Transmission characteristics of UV-curable silicone-coated optical fibre were investigated in relation to the elastic property and the chemical structure of the coating. It was found that added loss of the coated fibre is less than ±0.06 dB/km in the range ?75 to 80°C. The infra-red loss increase of the UV-curable silicone-coated fibre was appreciably lower than that for thermally cured silicone-coated fibre at elevated temperatures.     

OH absorption-induced loss in tapered singlernode optical fibre

Observation of the OH induced absorption loss near 1.39 μm in optical fibres tapered using a flame brushing technique is reported. The induced loss is experimentally analysed in terms of tapering conditions, fibre type, and annealing conditions. Impacts of the OH induced loss on fused taper fibre devices are discussed     

Germanium-dopant effect on hydroxyl loss increase in optical fibers

The germanium-dopant effect on hydroxyl loss increase in optical fibers is studied experimentally. The distribution profile of hydroxyl absorption which is caused by hydrogen diffusion is measured for GeO2-doped silica glasses. From the experiment, it is found that the distribution profile of induced hydroxyl absorption is similar to the GeO2concentration profile. Moreover, the absorption loss increases due to hydrogen diffusion are measured for GeO2-doped silica fibers. From the experiment, it is concluded that the induced molecular hydrogen loss as well as the induced hydroxyl loss increases with an increase in the GeO2concentration.     

Single-mode optical fibre microbending loss in a loose tube coating

45 km of single-mode fibre of differing detailed design has been loose-tube packaged under identical conditions. The spectral loss between 1.1 and 1.75 ?m was measured before and after packaging. The incremental loss thus deduced, and related to equivalent core size and ?n, provided information about fibre design for safe packaging.     

Low loss high-density optical cable with nylon-extruded fibre units

A low loss, highly dense cable containing nylon-extruded six-fibre units was examined. Suitable unit parameters were determined by measuring loss increases with lateral force and at low temperature. 216-fibre cable was manufactured using the nylon-extruded units, and cabling loss increase was found to be only 0.1 dB/km.     

熔融拉锥型光纤耦合器损耗的实验研究

结合2×2熔锥型光纤耦合器的制作,实验研究了拉锥速度、耦合长度、火焰位置3个关键制作参数对耦合器的插入损耗和附加损耗影响。当拉锥速度控制在150μm/s时,耦合器的插入损耗和附加损耗可以控制在较低水平;在拉锥长度较短的区间内,插入损耗与拉锥长度基本成线性关系;制作低损耗耦合器,火焰存在最佳高度为5.75 mm。     

Bandwidth and loss measurements of graded-index microstructured polymer optical fibre

The first bandwidth measurements of graded-index microstructured optical fibres are presented, demonstrating that this novel fibre geometry can provide high-bandwidth multimode polymer fibres without the need for complex doping techniques as with conventional polymer fibres.     

Transmission loss increase in optical fibres due to hydrogen permeation

The experiment of soaking the optical fibre cable in water is carried out. As a result, a tremendously large transmission loss increase is observed at 1.24 ?m. Through a fundamental experiment, it is shown that hydrogen permeation causes the transmission loss increase in optical fibres.     

Fabrication of long lengths of low excess loss erbium-doped optical fibre

Reports the fabrication of uniformly-doped, very low erbium concentration, silica-based fibre with negligible background loss. These fibres will facilitate distributed amplification over distances greater than 1 km for loss compensation in linear or non-linear systems.<>     

Transmission loss of thermotropic liquid-crystal polyester-jacketed optical fibre at low temperature

The transmission loss at low temperature of an optical fibre tightly jacketed with a new low-linear-expansion-coefficient plastic, thermotropic liquid-crystal polymer, is reported. The new type of tight-jacket fibre is free from microbending losses due to jacket contraction when exposed to heat cycles from ?70 to 80°C.     

Continuous measurement of optical fibre transmission loss characteristics during drawing process

An online measurement method using an optical rotary connector is proposed for continuously monitoring optical fibre loss characteristics during manufacture. This method provides a complete transmission loss spectrum and OTDR measurements of optical fibres during the drawing process. The results coincide with corresponding offline cutback measurements to better than ±0.2 dB/km.     

Molecular hydrogen behaviour for loss increase of silica fibre in cable filled with water

Evaluation of molecular hydrogen diffusion into silica fibre, which causes a loss increase at 1.24 ?m wavelength, and the accumulation mechanism for hydrogen in cable are reported. It has been found that loss increase around 1.24 ?m wavelength due to hydrogen greatly depends on the ambient hydrogen pressure. The hydrogen pressure in LAP sheath cable easily increases due to metal corrosion and the sealing effect of the sheath.     

Relation between splice loss and mode conversion in a graded-index optical fibre

To design an optical-transmission-line system, transmission characteristics of splices made by arc-fusion and V-groove methods were investigated experimentally for a graded-index optical fibre. It was found that the splice made by the arc-fusion method had a larger mode conversion than the splice made by the V-groove method for the same loss.