Low crosstalk polarisation-maintaining optical fibre with an 11 km length

An 11 km-long polarisation-maintaining optical fibre with crosstalk up to ?25.2 dB and ?22.5 dB at 1.30 ?m and 1.56 ?m, respectively, is presented. Transmission loss is 1.2 dB/km at 1.3 ?m and has a minimum value of 0.79 dB/km at 1.56 ?m.     

3 km-long single-polarisation single-mode fibre

A single-polarisation single-mode (SPSM) fibre with crosstalk of ?40 dB in a 3.2 km length has been demonstrated. No crosstalk degradation was found for lengths of more than 0.2 km. The two polarisations of the fundamental mode were split with a high modal birefringence of 8.5×10?4, which was produced by PANDA structure. The transmission loss was 2.8 dB/km at 1.56 ?m.     

Low-loss dispersion-shifted polarisation-maintaining fibres

Low-loss polarisation-maintaining fibres, with the zero dispersion wavelength shifted to 1.56 ?m, have been fabricated. A minimum transmission loss of 0.27 dB/km and crosstalk of ?22dB over a length of 4.1km, corresponding to h = 1.53 × 10-6m-1, are achieved at the same wavelength.     

Bidirectional 2 Mbit/s transmission over a single fibre using electrical echo cancellation

Bidirectional transmission over a single fibre using directional couplers and analogue echo cancellation is demonstrated. The implemented echo canceller suppresses crosstalk due to reflections from the local connector and coupler by 11 dB, i.e. it extends the transmission distance by up to 10 km (at 1.3 ?m).     

26 km-long polarisation-maintaining optical fibre

The letter describes the development of a long-length and large-diameter preform for polarisation-maintaining optical fibres. The preform was 470 mm in length and 48 mm in diameter. As a result, a 26 km-long PANDA fibre is developed. This fibre achieves crosstalk of ?22 dB, corresponding to h = 2.4 × 10-7m-1 and a transmission loss of 0.3 dB/km at a wavelength of 1.56 ?m. These fibres will be useful for future high-speed and medium-span coherent optical communications.     

WDM experiment using 1300/1500 nm dual-wavelength LED for single-mode fibre transmission systems

A wavelength-division-multiplexing transmission experiment using a 1300/1500 nm dual-wavelength LED modulated at 140/560 Mbit/s over 10 km of single-mode fibre has been demonstrated. This dual-LED device has a 9 ?m emitter spacing between the active facets with a coupling loss of 2.3 dB through a lens/fibre coupler. The chromatic dispersion penalty for the 1500 nm channel at 560 Mbit/s was about 6-5 dB and the electrical crosstalk penalty was 2.5 dB.     

Low-loss splicing of a 62.4 km single-mode-fibre link

A 62.4 km single-mode-fibre link containing 35 splices has been made in the laboratory using equipment and techniques suitable for landline installations. Mean splice attenuations of 0.1 dB at 1.3 ?m and 0.08 dB at 1.55 ?m were measured. The mean attenuation of the complete spliced link was 0.5 dB/km at 1.3 ?m and 0.34 dB/km at 1.55 ?m. In addition, the attenuations of 200 splices measured at 1.3 ?m are reported.     

Optimised structure for preparing long ultra-low-loss single-mode fibres

An optimised structure has been evolved for producing long lengths of ultra-low-loss single-mode fibre. Attenuation figures of 0.6 dB/km at 1.3 ?m and 0.34 dB/km at 1.6 ?m have been achieved in fibres up to 17.1 km in length. The absorption due to OH impurity has been reduced to <3 dB/km at 1.39 ?m.     

Guided-wave optical wavelength-division multi/demultiplexer using high-silica channel waveguides

A guided-wave optical waveguide-division multi/demultiplexer for bidirectional transmission at (0.81 ?m, 1.2 ?m)/(0.89 ?m, 1.3 ?m) wavelengths has been realised using high-silica channel waveguides on silicon substrate. The multi/demultiplexer connected with graded-index multi-mode fibres shows a loss of 3.5?5 dB together with far-end and near-end crosstalk levels less than ?30 dB and ?50 dB, respectively.     

Prediction of loss minima in infra-red optical fibres

Loss minima in two fluoride glass and chalcogenide glass fibres were calculated. The intrinsic losses are predicted to be 1 × 10?3 dB/km at 3.4 ?m for BaF2-GdF3-ZrF4 glass fibre, 1 × 10?2 dB/km at 2.7 ?m for BaF2-CaF2-YF3-AlF3 glass fibre and 1 × 10?2 dB/km at 4.5 ?m for GeS3 glass fibre.     

Design and fabrication of dispersion-shifted depressed-clad triangular-profile (DDT) single-mode fibre

A new depressed-clad triangular-index-profile single-mode fibre with dispersion minimum shifted to the 1.55 ?m region is investigated. Fibres with high cutoff wavelength (?1.1 ?m) and low dispersion slope (?0.052 ps/km nm2) at their minimum dispersion wavelength (?1.55 ?m) were fabricated. Results from 226.7 km of fibre show an average loss of 0.241 dB/km at 1.55 ?m and 0.232 dB/km at the loss minimum.     

100 km single mode VAD fibres

100 km single mode fibres with low loss values of 0.3 dB/km at 1.55 ?m and 0.5 dB/km at 1.3 ?m have been made by the VAD method. Swept frequency 6 dB down bandwidths at the two wavelengths were 40 MHz for 100 km length and 800 MHz for 50 km length, respectively.     

Electrical and acoustical crosstalk in integrated optical strip waveguide devices

Observations of electrically and acoustically induced crosstalk in LiNbO3 waveguide phase modulators at ? = 0.633 ?m are reported. In the tested device, crosstalk attenuation was as low as 23 dB at 700 MHz and 29 dB at 22.83 MHz, which is caused by RF electromagnetic field coupling and by acoustical coupling, respectively, Crosstalk measurements are made as a function of frequency in the electrical and optical domain.     

New low-loss liquid-core fibre waveguide

Low-loss liquid-core fibre-optical waveguides having a transmission loss of 10 dB/km has been made using commercially available glass tubing. The loss is less than 20 dB/km over a wavelength range of greater than 0.8?1.1 ?m, and, at the semiconductor laser wavelength of 0.9 ?m, has a value of 14 dB/km. This is the first low-loss fibre to be made using glass.     

Fabrication of low-loss and wide-bandwidth v.a.d. optical fibres at 1.3 ?m wavelength

A low-loss and wide-bandwidth optical fibre in the long-wavelength region has been fabricated by the v.a.d. method. Loss at 1.3 ?m is 0.98 dB/km and 6 dB down bandwidth is 1600 MHz km at 1.26 ?m.     

InGaAsP/InP dual-wavelength BH laser array

A dual-wavelength BH laser array emitting at 1.26 and 1.55 ?m has been fabricated. Spacing between the two BH lasers is 30 ?m, and simultaneous CW operation of the two lasers at room temperature has been achieved. Measured crosstalk was ?50 dB.     

Tunable fibre Raman oscillator in the 1.32?1.41 ?m spectral region using a low-loss, low OH? single-mode fibre

We report the first tunable fibre Raman oscillator in the 1.32?1.41 ?m spectral region using a 1 km-long low-loss (0.32 dB/km at 1.32 ?m) and low OH? (1 dB/km at 1.39 ?m) single-mode fibre as the nonlinear medium, and a CW mode-locked Nd: YAG laser at 1.32 ?m as the pump source.     

Transmission loss characteristics of fluoride glass single-mode fibre

The transmission loss spectrum of a fluoride glass single-mode fibre as obtained with a new preform fabrication technique is shown. It is clearly confirmed on the loss spectrum that the obtained fibre is a single-mode waveguide in the minimum loss wavelength range (2?4 ?m). The minimum loss of this fibre is 8.5 dB/km at 2.2 ?m and the OH excess loss is 15dB/km at 2.85 ?m. This fabrication technique is effective in eliminating OH contamination.     

Germanium-oxide glass optical fibre prepared by VAD method

Germanium-oxide glass optical fibre doped with antimony for transmission of the 2 to 3 ?m band has been prepared by the vapour-phase axial deposition (VAD) method. An attenuation loss of 13 dB/km at 2.05 ?m and 70 dB/km at 2.4 ?m has been achieved.     

Low-OH MCVD fibres without a barrier layer using OH ? OD-exchanged substrate tubes

The effect of deuteration (OH ? OD exchange) of the MCVD substrate tube on the absorption loss in fibres was studied using tubes of moderate and low OH content. The OH absorption at 1.39 ?m was reduced from 4 dB/km and 0.9 dB/km to 1 dB/km and 0.7 dB/km, respectively, in fibres made without a barrier layer using deuterated tubes.