160 Gbit/s OTDM signal transmission over 26 km photonic crystal fibre

A 160 Gbit/s (=10 Gbit/s X 16) optical time-division multiplexing (OTDM) signal is successfully transmitted over a 26 km-long photonic crystal fibre (PCF). The transmission induced signal pulse broadening is suppressed to only 0.2 ps (from 2.1 to 2.3 ps) because the fabricated PCF has low polarisation-mode dispersion (PMD) of 0.1 ps/km^1/2, and the total chromatic dispersion of the transmission line is suppressed to 0.015 ps/nm by using a dispersion-compensation fibre. The transmitted signal is demultiplexed using four-wave mixing in a 100 mlong dispersion shifted fibre, where a phase modulation-based 10 GHz pump pulse source is newly adopted.     

Picosecond pulse generation with high extinction ratio employing electroabsorption modulator, fibre compressor, and self-phase-modulation-based pulse reshaper

A wavelength-tunable 3.5 ps pulse generator, which employs an electroabsorption modulator (EAM), a fibre pulse compressor, and a self-phase-modulation (SPM)-based pulse reshaper, is developed. An EAM directly generates 21 ps pulses at a repetition rate of 10 GHz, which are compressed to 6 ps by a fibre pulse compressor. An SPM-based pulse reshaper then eliminates the large pedestal of the compressed pulses. Thus, 3.5 ps pulses with extinction ratio larger than 27 dB and timing jitter as small as 150 fs are obtained.     

Flatly broadened supercontinuum generation at 10 Gbit/s using dispersionflattened photonic crystal fibre with small normal dispersion

Supercontinuum generation at 10 Gbit/s using a nonlinear dispersion-flattened photonic crystal fibre is experimentally demonstrated. The fibre has small normal dispersion with a variation smaller than 1.5 ps nm^-1 km^-1 between 1500 and 1650 nm. The supercontinuum with a flatly broadened spectrum of 92 nm (at 6 dB) in the 1.55 mum region is generated by injecting 1545 nm, 1.5 ps optical pulses into an 80 m-long fibre     

Picosecond soliton pulse-duration-selectable source based onadiabatic compression in Raman amplifier

Raman amplified 10 ps soliton pulses generated directly from an electroabsorption modulator based source have been adiabatically compressed in a Raman fibre amplifier, giving pulse duration tunable sources of 10-1 ps at 10 GHz and average powers up to 650 mW, dependent on the magnitude of the amplification     

Generation of 6.3 ps optical pulses at a 10 GHz repetition rateusing a packaged electroabsorption modulator and dispersion compensatingfibre

Sinusoidal modulation of an MQW InGaAsP/InGaAsP EA modulator at a 10 GHz repetition rate was used to generate optical pulses of width as low as 7 ps. Pulses were linearly compressed using 400 m of dispersion compensating fibre and approximately transform limited pulses of 6.3 ps width were measured     

Soliton transmission over more than 90 km using distributederbium-doped fibres

The transmission of 11.5 ps solitons over 93.4 km of distributed erbium-doped fibre is reported. By inserting a 29.3 km long midsection singlemode fibre instead of 32.5 km of erbium-doped fibre, the signal excursions are lowered, and 9.0 ps solitons are transmitted over 90.2 km     

Generation of 10 nJ picosecond pulses from a modelocked fibre laser

Wavelength-tunable very high power soliton fibre lasers are constructed using chirped fibre Bragg gratings. Near-bandwidth limited pulses with widths of 4.0 ps and pulse energies up to 10 nJ are generated directly from passively modelocked erbium fibre lasers. A stable pulse repetition rate of 17 MHz is obtained, giving rise to an average modelocked output power of 170 mW     

Optical pulse compression in 1.5 μm wavelength region usinglarge-positive-dispersion fibre and grating pair

Optical pulse compression at 1.5 μm has been conducted. 20 ps (FWHM) optical pulses from a Tl:KCl-colour-centre laser were compressed into pedestal-free 1.2 ps pulses using a large-positive-dispersion fibre and a grating pair. In addition, 280 fs pulses were obtained from the resultant 1.2 ps through the soliton compression effect in a negative-dispersion fibre     

Measurement of broadening of pulses in glass fibres

In the letter is reported the measurement of broadening of pulses in glass fibres using a GaAs injection laser diode as an emitter and a germanium photodiode as a detector. We found broadening of about 5 ps/m for a multimode fibre and 0.6 ps/m for a self-focusing glass fibre.     

Study of pulse distortion in Selfoc fibres

A 100 ps gallium-arsenide laser pulse was observed to increase in width by only 100 ps in 70 m of a fibre with an internal refractive-index gradient (Selfoc). This is shown to be in satisfactory agreement with a simple ray analysis which neglects the index discontinuity at the fibre wall.     

Polarisation mode dispersion measurements in long single mode fibres

A new method to measure polarisation mode dispersion is described, in which the accuracy is more than 0.1 ps. 0.17 ps polarisation mode dispersion was obtained for about 1 km length of fibre. The result is compared with the retardation obtained for a short length of the fibre.     

Compresion and dispersionless transmission of chirped 1.3 mu m DFB ps laser pulses in dispersion-shifted single-mode fibres

Optical pulse compression of high-speed gain-switched ps 1.3 mu m DFB semiconductor laser pulses in dispersion-shifted single-mode fibres is measured with a streak camera. The laser-red-shift chirp is compensated for by the negative chromatic fibre dispersion, resulting in pulse compression and 'dispersionless' transmission of 45 ps pulses over 12 km of fibre.<>     

Dispersion compensation of 16 ps pulses over 100 km of step-indexfibre using cascaded chirped fibre gratings

The propagation of 16 ps data pulses over 100 km of step-index fibre using two cascaded chirped fibre gratings to achieve dispersion compensation is presented. At the output, the pulses are broadened slightly to 20 ps, indicating the potential for 50 Gbit/s operation     

Antisymmetric pulse generation using phase-shifted fibre Bragggrating

A 10 mm Bragg grating with a 0.18 nm (peak-to-peak) spectral response was designed to shape a train of 7 ps Gaussian pulses into antisymmetric Hermite-Gauss pulses. The pulses were characterised in the frequency and time domain. The presence of the phase shift was verified by propagation in standard fibre     

Minimum-dispersion spectra of single-mode fibres measured with subpicosecond resolution by white-light crosscorrelation

The minimum-dispersion spectrum of a single-mode silica fibre has been measured with 0.1 ps resolution by a crosscorrelation method using a CW halogen lamp source and a Mach-Zehnder fibre interferometer configuration.     

160 Gbit/s soliton data transmission over 200 km

Polarisation- and time-domain-multiplexed 160 Gbit/s soliton signals have been successfully transmitted over 200 km for the first time. The soliton source was a 10 GHz regeneratively modelocked fibre laser and a planar lightwave circuit was used for optical multiplexing. The soliton pulse width was ~1.5 ps. A polariser and a nonlinear loop mirror were used for demultiplexing from 160 to 10 Gbit/s     

Wavelength dispersion in a single-mode fibre

Wavelength dispersion in a single-mode fibre has been evaluated by measuring propagation times of various-wavelength pulses transmitted through a 3.72 km-length fibre. Dispersion in a single-mode fibre is dominated by material dispersion, and is estimated to be 9.1 ps/? dkm at 0.85 ?m wavelength.     

Miniature packaged actively mode-locked semiconductor laser with tunable 20 ps transform limited pulses

Miniature, fibre tailed and packaged, wavelength tunable actively mode locked semiconductor lasers have been developed for use as sources of approximately 20 ps transform limited pulses. Continuous stable operation with >40 nm tuning ranges centred either at 1.3 mu m or 1.55 mu m have been demonstrated. The package has an adjustable cavity length enabling the repetition frequency to be selected between 2 GHz and 8 GHz. Mean output powers in the monomode fibre tail are in the range -10 dBm to -5 dBm.<>     

Dispersion slope equaliser using bend-induced positive dispersionslope in coiled pure-silica fibre

The dispersion slope of a dispersion-shifted fibre has been successfully equalised by using a bend-induced positive dispersion slope in a singlemode fibre. We realised the bent fibre dispersion slope equaliser by using a 1.3 μm zero-dispersion pure silica core fibre (PSM). This equaliser provides a dispersion slope of -12.54 ps/nm² /km in the 1.5 μm region     

Active mode-locking of an external cavity GaInAsP laserincorporating a fibre-grating reflector

Active mode-locking of a GaInAsP semiconductor diode amplifier, coupled to an external cavity incorporating an optical fibre grating as a bandwidth limiting and wavelength selective mirror, is reported. The grating defined the central emission wavelength to the 1.53 μm region where mode-locked pulses having durations of less than 10 ps were generated at a repetition rate of 648 MHz