4 Gb/s soliton data transmission over 136 km using erbium dopedfiber amplifiers

The use of semiconductor-laser-pumped erbium-doped fiber amplifiers and an externally modulated mode-locked external-cavity semiconductor laser to obtain soliton data transmission at 4 Gb/s over 136 km of nondispersion shifted fiber is described. After 136 km of transmission and at low pulse powers, the ~80 ps fiber input pulse width was broadened to ~150 ps. At high pulse powers the output pulse width was maintained at 80 ps, as expected for N=1 solitons. N =3 solitons were also observed at lower data rates     

10-Gb/s optical transmission up to 253 km via standard single-modefiber using the method of dispersion-supported transmission

Using the new method of dispersion-supported transmission, 10 Gb/s signals at 1.53 μm wavelength are transmitted on standard single-mode fiber with zero dispersion at 1.3 μm via the record length of 253 km without in-line regeneration. Detailed experiments with a directly modulated laser demonstrate the system performance for different fiber lengths ranging from 0 up to 253 km     

1.7 Gbit/s transmission over 165 km of dispersion-shifted fibreusing spectrum-sliced fibre amplifier light source

The authors have demonstrated 1.7 Gbit/s transmission over 165 km of dispersion-shifted fibre using a spectrum-sliced fibre amplifier light source. To the authors' knowledge, this represents the largest bit-rate distance product (280 Gbit/s km) ever demonstrated using an incoherent light source. The dispersion penalty was very small (~0.3 dB) even at a wavelength 10 nm away from the dispersion-zero wavelength of the fibre     

10 Gbit/s, 300 km repeaterless transmission with SBS suppression bythe use of the RZ format

The authors have confirmed experimentally that employing the RZ format instead of the NRZ format increases the SBS threshold by ~3 dB. By using the RZ format, we have successfully conducted 10 Gbit's repeaterless transmission through 300 km of DSF. This is the longest repeaterless transmission at 10 Gbit/s ever reported     

Fiber transmission for sub-500-fs pulses using adispersion-compensating fiber

We report transmission of ~60-fs and ~245-fs pulses, respectively, over 42-m and 2.5-km fiber links which consist of standard single-mode fibers (SMF) concatenated with dispersion-compensating fibers (DCF). The experiments using very short pulses (~60 fs) over a short fiber length (~42 m) demonstrate the ability to achieve simultaneous dispersion and dispersion slope compensation using this technique. Femtosecond spectral interferometry measurements of this 42-m link show that its residual dispersion slope is approximately six times lower than that of the dispersion-shifted fiber. Finally, to demonstrate that the dispersion-limited propagation distance is proportional to the cube of the pulsewidth, we transmit ~245-fs pulses over a 2.5-km SMF-DCF link and achieve comparable pulse restoration as with the shorter fiber experiments     

8 Gbit/s transmission over 30 km of optical fibre

We demonstrate, for the first time, 8 Gbit/s digital transmission over single-mode optical fibre. A 30 km link was achieved using a directly modulated 1.31 ?m multilongitudinal-mode laser and an avalanche photodiode receiver.     

40 Gbit/s transmission over 202 km of standard fibre using midspanspectral inversion

The authors demonstrate for the first time the transmission of a 4×10 Gbit/s OTDM data sequence over two unrepeatered links of 100 km of nondispersion shifted fibre. The experiment is enabled using midspan spectral inversion and electroabsorption modulator sources and demultiplexers, and results in a record bit-rate-distance product of 8.1 Tbit/s km for a single channel over standard fibre     

2.488 Gbit/s transmission experiment at 1550 nm over 153 km standard single-mode fibre

The transmission experiments demonstrate that operation of 2.488 Gbit/s optical transmission systems over more than 150 km standard SMF is not dispersion limited using today's 1550 nm DFB-lasers. With an extinction ratio as low as 11 dB a dispersion and extinction ratio penalty of less than 0.7 dB was observed.<>     

Long-span repeaterless transmission systems with optical amplifiersusing pulse width management

This paper proposes pulse width management in order to extend the repeater spacings of repeaterless transmission systems with optical amplifiers. First, the dependency of receiver sensitivity on duty ratio, receiver response, and fiber dispersion is clarified by numerical analysis. Next, the calculation results of sensitivity as a function of signal format and receiver basedband response are verified experimentally. Moreover, we show that pulse width management which uses return-to-zero (RZ) format with large duty ratio (~0.7) at the transmitter and pulse compression at the receiver increases the repeater gain by ~4.5 dB compared to conventional systems employing nonreturn-to-zero (NRZ) format. Record repeater spacing of 300 km is realized at 10 Gb/s by utilizing pulse width management     

40G比特/秒 FSK传输链接的理论和实证研究

A novel Frequency Shift Keying (FSK) transmitter that can operate at 40Gb/s and above is proposed. The transmission characteristics of a FSK signal at 40Gb/s are investigated under varying dispersion management. The resilience of compensation ratio and power level is obtained. We also experimentally demonstrate transmission over 100km SMF and transparent wavelength conversion based on a semiconductor optical amplifier.     

Long-span single-mode fiber transmission characteristics in long wavelength regions

Experimental and analytical results on high-speed optical pulse transmission characteristics for long-span single-mode fibers by using InGaAsP lasers, emitting at 1.1, 1.3, and 1.5 μm, as well as a Ge-APD are reported. At 1.1 μm, 400 Mbit/s transmission experiments were successfully carried out with 20 km repeater spacing. At 1.3 μm, where single-mode fiber dispersions approach zero, error rate characteristics showed that optical power penalties at 100 Mbits/s and 1.2 Gbits/s are negligible even after 30 and 23 km fiber transmission, respectively. It was confirmed that a 1.6 Gbit/s transmission system has 15 km repeater spacing. At 1.5 μm, where silica fibers have ultimately minimum loss, single-mode fiber transmission experiments were carried out at 100 Mbits/s with about 30 km repeater spacing. 400 Mbit/s transmission characteristics using 20 km fibers were also studied. Fiber bandwidths, measured by optical pulse broadenings after 20 km transmission, were 24, 140, and 37 GHz . km . nm at 1.1, 1.3, and 1.5 μm, respectively. Progress in lasers, fibers, and optical delay equalizers at 1.5μm will bring about large-capacity transmission systems having about 150 km repeater spacing. These results reveal fiber dispersion characteristics in the long wavelength region essential to high data rate single-mode fiber transmission system design.     

Single- and alternating-polarization 170-gb/s transmission up to 4000 km using dispersion-managed fiber and all-Raman amplification

We demonstrate transmission of 170-Gb/s single- and alternating-polarization return-to-zero differential phase-shift keying signals in a recirculating loop using dispersion-managed fiber spans and all-Raman amplification. In the single polarization case, bit-error-ratio (BER) values of 5/spl times/10/sup -9/ and 1.6/spl times/10/sup -4/ were obtained after 960 and 2880 km, respectively. In the alternating polarization case, significantly larger transmission distances were achieved, with BER values of 2/spl times/10/sup -9/ after 1920 km and 5/spl times/10/sup -5/ after 4320 km, respectively.     

30-gb/s signal transmission over 40-km directly modulated DFB-laser-based single-mode-fiber links without optical amplification and dispersion compensation

Based on a recently proposed novel optical-signal-modulation technique of adaptively modulated optical orthogonal frequency-division multiplexing (AMOOFDM), numerical simulations of the transmission performance of AMOOFDM signals are undertaken in directly modulated DFB laser (DML)-based single-mode-fiber (SMF) links without optical amplification and dispersion compensation. It is shown that a 30-Gb/s transmission over a 40-km SMF with a loss margin of greater than 4.5 dB is feasible in the aforementioned simple configuration using intensity modulation and direct detection (IMDD). In addition, the DFB-laser frequency chirp and the transmission-link loss are identified to be the key factors limiting the maximum achievable transmission performance of the technique. The first factor is dominant for transmission distances of < 80 km and the second one for transmission distances of > 80 km. It is also observed that fibers of different types demonstrate similar transmission performances, on which fiber nonlinear effects are negligible.     

240-km CWDM transmission using cascaded SOA Raman hybrid amplifiers with 70-nm bandwidth

We demonstrate the cascading of broad-band semiconductor optical amplifier-Raman hybrid amplifiers which provide nearly flat gain over 70 nm. A coarse-wavelength-division-multiplexing transmission system consisting of three spans of 80 km shows uniform performance and <1-dB power penalty.     

Feasibility of densely dispersion managed soliton transmission at160 Gb/s

We numerically demonstrate 160 Gb/s densely dispersion-managed soliton transmission in a single channel over 2000 km in the dispersion-flattened fibers in the presence of polarization mode dispersion and of large variation in group-velocity dispersion. The best performance is achieved by a proper design of the dispersion profile with possible minimum average dispersion, so that the soliton interactions are minimized     

IM-DD long-distance multichannel WDM transmission experiments usingEr-doped fiber amplifiers

We have demonstrated multichannel wavelength-division multiplexed optical signal transmission experiments employing Er-doped fiber amplifiers. Four-channel transmission of 459 km and 1500 km experiments and two-channel transmission of 4550 km experiment are described, and the transmission penalty is analyzed. We also discuss the effect of four-wave mixing. The difference of the transmission fiber clearly shows the difference of the optical spectrum due to four-wave mixing after long-distance transmission. The results show the possibility of long-distance multidestination optical communication systems with wavelength-division multiplexed signals combined with Er-doped fiber amplifiers     

Optical time-division multiplexing and demultiplexing in a multigigabit/second fibre transmission system

We demonstrate an optical time-division-multiplexed fibre transmission system using actively mode-locked InGaAsP injection lasers and high-speed Ti:LiNbO3 switch/modulators. Two 2Gbit/s return-to-zero data streams are optically multiplexed to 4Gbit/s, transmitted through 8 km of fibre, optically demultiplexed and detected with low error rate.     

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     

Trans-oceanic 160-Gb/s single-channel transmission usingshort-period dispersion management

We demonstrate, by numerical simulation, the possibility of 160-Gb/s single channel transmission over distances >8000 km with no active control using a short-period dispersion managed fiber, in the absence of polarization-mode dispersion (PMD). The performance of this system is limited by the growth of continuous-wave background instabilities, resulting from strong filtering, and the accumulation of jitter. However, when introduced, the effects of PMD become the dominant limiting factor     

Demonstration of 2.488 Gbit/s transmission on the UK—Channel Islands No 7 submarine cable system

The recently-installed UK—Channel Islands No 7 cable system is a 132 km unrepeatered, twelve optical fibre, 140 Mbit/s system. In February the cable was used for a series of tests to demonstrate new transmission and receiver equipment developed at British Telecom Research Laboratories (BTRL). The paper describes first the use of erbium fibre power amplifiers to achieve two-way transmission over the system at 2.488 Gbit/s, and then the testing of a novel semi-ruggedised laser PIN receiver.