20 Gb/s optical soliton data transmission over 70 km usingdistributed fiber amplifiers

20 Gb/s optical soliton data transmission is demonstrated over 70 km. Highly efficient distributed Raman amplifiers for fiber-loss compensation are realized by using high Δn dispersion-shifted single-mode fibers pumped by laser diodes. To achieve high bit rate transmission, optical multiplexing and demultiplexing techniques are also employed. The bit error rate (BER) performance dependence on the input peak power of the optical pulse is measured. No power penalty can be seen at the input peak power required for transmitting optical solitons while the BER performance degrades when decreasing the input peak power     

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     

10 Gbit/s, 1200 km error-free soliton data transmission using erbium-doped fibre amplifiers

Soliton data signals at 10 Gbit/s have been successfully transmitted for the first time through a 1200 km dispersion-shifted fibre by using 24 erbium-doped fibre amplifiers. A bit error rate below 10/sup -13/ was obtained with 2/sup 20/-1 pseudorandom patterns.<>     

10 Gbit/s pseudorandom dark soliton data transmission over 1200 km

A 10 Gbit/s pseudorandom (PR) dark soliton data signal has been successfully transmitted over 1200 km for the first time. The dark soliton source was a 1.53 μm DFB LD and was modulated with a push-pull Mach-Zehnder LiNbO₃ intensity modulator. A T-flip-flop circuit was used to generate the PR dark soliton. A one-bit-shifting scheme with a Mach-Zehnder interferometer was used to convert the dark soliton train into a conventional NRZ signal     

Polarisation-independent 20 Gbit/s soliton data transmission over12500 km using amplitude and phase modulation soliton transmissioncontrol

Polarisation-independent error-free 20 Gbit/s soliton data transmission over 12500 km with flat system Q dependence on distance, has been demonstrated using static filtering and a semiconductor polarisation-independent amplitude and phase modulator for soliton transmission control     

Inline amplifier transmission experiments over 4500 km at 2.5 Gb/s

An inline amplifier system was constructed with erbium-doped fiber amplifiers spaced at 100 km and 80 km intervals. The system transmits 2.5 Gb/s signals over 2500 km with continuous-phase frequency-shift-keying heterodyne detection and over 4500 km with intensity-modulation direct detection. With respect to amplifier output signal power levels, it is experimentally shown that there exists a dynamic range within which long-distance signal transmission can be achieved with only small receiver sensitivity degradation. The range's upper and lower limits are determined by fiber nonlinearities and amplifier noise characteristics, respectively     

3.2-5 Gb/s, 100 km error-free soliton transmission with erbiumamplifiers and repeaters

For the transmissions, the transform-limited soliton pulse source is a gain-switched distributed-feedback laser diode with a narrowband spectral filter and erbium amplifiers. A LiNbO₃ light intensity modulator is used for pulse switching. The preemphasis technique for sending solitons over a long distance, in which an erbium optical repeater is installed every 25 km as a lumped amplifier, is used     

2.488 Gb/s-318 km repeaterless transmission using erbium-dopedfiber amplifiers in a direct-detection system

The authors have achieved a 2.488 Gb/s, 318 km repeaterless transmission without any fiber dispersion penalty through a nondispersion-shifted fiber in a direct detection system. The system was loss limited with a T-R power budget of 57 dB. Three key components enabled the authors to achieve this result: (1) a Ti:LiNbO₃ external amplitude modulator enabling a dispersion-free transmission, (2) erbium-doped fiber amplifiers increasing the transmitting power to +16 dBm, and (3) an erbium-doped fiber preamplifier enabling a high-receiver sensitivity of -4.1 dBm for 10^-9 BER. To the author's knowledge, this result is the longest repeaterless transmission span length ever reported for direct detection at this bit rate. From the experimental results and a theoretical model, the authors identified the sources of the receiver sensitivity degradation from the quantum limit (-48.6 dBm) and estimated the practically achievable receiver sensitivity of ~-44 dBm (~-124 photons/bit) for 2.5 Gb/s optical preamplifier detection     

252 km repeaterless 10 Gb/s transmission demonstration

Using a practical erbium-doped fiber postamplifier, a dual-stage optical preamplifier, a lithium niobate Mach-Zehnder external modulator and a dispersion-shifted line fiber, IM/DD repeaterless transmission over 252 km at 10 Gb/s with a wavelength-independent receiver sensitivity in the 1530-1565-nm range is achieved     

80 Gbit/s soliton data transmission over 500 km with unequalamplitude solitons for timing clock extraction

Single-polarisation 80 Gbit/s soliton data signals have been successfully transmitted over 500 km. The soliton source was a modelocked fibre laser and a planar lightwave circuit was used for stable optical multiplexing. A nonlinear loop mirror was used for demultiplexing, in which unequal amplitude solitons were used for clock extraction     

3.6 Gb/s all laser-diode optical soliton transmission

3.6-Gb/s optical soliton transmission using a gain-switched 1.55-μm distributed-feedback laser diode and a Ti:LiNbO₃ intensity modulator is demonstrated. An Er³⁺-doped fiber amplifier and a Raman amplifier, both pumped by 1.48-μm laser diodes, are used for achieving intense optical pulses and fiber-loss compensation, respectively. The intensity-modulation direct-detection optical receiver of a commercial F-1.6 G system is used to measure the bit-error rate     

Unrepeatered 2.4 Gbit/s transmission experiment over 250 km of step-index fibre using erbium power amplifier

An erbium power amplifier is used to give a system launch power in excess of +20 dBm. In conjunction with an FSK modulation technique this allows unrepeatered transmission over 250 km of step-index fibre with a loss of 50 dB and a total dispersion of 3930 ps nm/sup -1/.<>     

5 Gb/s optical soliton transmission experiment using Ramanamplification for fiber-loss compensation

Optical soliton transmission of 5 Gb/s over a 23-km amplification spacing using a gain-switched 1.55-μm distributed feedback laser diode and Ti:LiNbO₃ intensity modulator is discussed. An Er ⁺-doped fiber amplifier, pumped by 1.45- and 1.48-μm laser diodes, is employed for achieving intense optical pulses. Transmission fiber-loss is completely compensated for by Raman amplification using by 1.45- and 1.48-μm laser-diode pumping. A bit error rate (BER) of 2×10^-10 has been obtained     

Bandwidth efficient transmission of 4 Gb/s on two microwave QPSKsubcarriers over a 48 km optical link

The use of two quadrature phase shift keying (QPSK)-modulated subcarriers over a wideband direct detection optical communications system with a RF bandwidth efficiency of 1 b/s/Hz is reported. It is shown that two subcarriers each carrying 2 Gb/s QPSK, compactly spaced at just twice the data rate, can achieve a receiver sensitivity of -19.5 dBm over 48 km without crosstalk between subcarriers. This represents a receiver sensitivity improvement of 5 dB over a 4-Gb/s single QPSK subcarrier system     

400 Mbit/s, 372 km coherent transmission experiment using in-lineoptical amplifiers

Reports on an optical transmission experiment using four in-line optical amplifiers. With a net gain of 58000 (47.7 dB) from the amplifiers, the authors were able to increase the longest nonregenerated transmission distance to 372 km. The system penalty associated with the amplifiers was only 1.5 dB     

An over 2200-km coherent transmission experiment at 2.5 Gb/s usingerbium-doped-fiber in-line amplifiers

A 2223 km transmission distance was achieved with a 2.5-Gb/s heterodyne detection system that used erbium-doped-fiber in-line amplifiers and dispersion-shifted single-mode fibers. Twenty-five amplifiers, placed at approximately 80-km intervals, offered a total gain of more than 440 dB. Receiver sensitivity was -42.0 dBm, with only a 4.2-dB penalty from the initial sensitivity achieved by the back-to-back configuration     

20 Gbit/s soliton transmission over transoceanic distances with a105 km amplifier span

20 Gbit/s soliton transmission over large distances (150000 km) is demonstrated in a recirculating loop with a record amplifier span of 105 km. For the first time, an electroabsorption modulator is used to provide the necessary in-line modulation control     

Error-free soliton transmission at 20 Gbit/s over 7150 km throughall-optical synchronous phase modulation

All-optical soliton synchronous phase modulation through transmission fibre is shown to enable error-free propagation of 20 Gbit/s signals up to 7150 km without the need for dispersion management. Tolerance to imperfect clock-signal synchronisation is characterised experimentally     

10 Gbit/s optical soliton transmission over 7200 km by using amonolithically integrated MQW-DFB-LD/MQW-EA modulator light source

The authors demonstrate 10 Gbit/s optical soliton transmission in a recirculating loop through the use of a monolithically integrated MQW-DFB-LD/MQW-EA modulator light source. The timing jitter due to the Gordon-Haus effect is successfully reduced by the optical bandpass filters conventionally used in the cascaded EDFAs to avoid the accumulation of amplified spontaneous emission. The transmission distance of 7200 km is achieved at a bit error rate of 10^-9     

40 Gb/s single-channel soliton transmission over transoceanicdistances by reducing Gordon-Haus timing jitter and soliton-solitoninteraction

Forty Gb/s single-channel soliton transmission experiments using periodic dispersion compensation were conducted. The impact of the dispersion map on the transmission performance was experimentally investigated. The transmission performance was significantly varied with the dispersion map. The improvement of the transmission performance by the polarization division multiplexing, which reduced soliton-soliton interaction furthermore, was also confirmed. By using the polarization division multiplexing in the optimum dispersion map, 40 Gb/s single-channel transmission over 10200 km has been successfully demonstrated without any active inline transmission control