Optical Soliton Transmission Research Articles

Optical soliton transmission technology

In this paper, we describe soliton transmission experiments at 20-40 Gbit/s over 1000 km and new soliton transmission technologies. The experimental setup for the soliton data transmission is shown. 20 Gbit/s pulses were obtained by using an optical multiplexing technique with two 3 dB fiber couplers. For the 40 Gbit/s transmission experiment, a polarization multiplexing technique was used, which enabled the bit rate to be doubled. >

Optical Soliton Transmission System.

This paper describes the importance of distributed fiber dispersion and the waveform equalization with optical filtering technique in ultra-high speed and/or ultra-long distance optical soliton transmission.

Demonstration of error free optical solitontransmission over 30 000 km at 10 Gbit/s withsignal frequency sliding technique

10 Gbit/s optical soliton transmission in a recirculating loop is demonstrated. The signal frequency sliding technique is employed to reduce the accumulation of ASE noise and timing jitter. Error free (BER<10/sup -9/) soliton transmission over 30000 km is achieved.

10-GHz optical soliton transmission experiment in a sliding-frequency recirculating fiber loop

A 10-GHz optical soliton transmission experiment was performed in a recirculating fiber loop in which the carrier frequency was slowly shifted by an acousto-optic modulator with respect to an optical bandpass filter to simulate the sliding-frequency effect. The soliton pulses were transmitted over 4000 km without any significant change in pulse width.

Peak curvature measurement offrequency-guiding filter in optical solitontransmission

A novel technique is proposed to precisely measure the peak curvatures of the frequency-guiding filters used to reduce the timing jitter in optical soliton transmission. The peak curvatures are directly obtained by the synchronous detection method. The measured peak curvatures are in good agreement with those evaluated by their transfer functions.

10 Gbit/s optical soliton transmission over 7200kmby using a monolithically integratedMQW-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.

Suppression of noise accumulation in bandwidth-limited soliton transmission by means of nonlinear loop mirrors

It is shown numerically that the amplification and accumulation of noise and other dispersive waves in bandwidth-limited soliton transmission can be suppressed by the use of nonlinear amplifying loop mirrors that selectively amplify solitons. This scheme offers an alternative possibility for achieving stable ultralong-distance optical soliton transmission.

80 Gb/s optical soliton transmission over 80 km with time/polarization division multiplexing

Time/polarization-division multiplexed optical solitons are successfully transmitted at 80 Gb/s over an 80 km dispersion-shifted single-mode-fiber. The 80 Gb/s optical pulse trains are generated by optically multiplexing 10 Gb/s gain-switched pulse trains. The transmitted solitons are demultiplexed with a polarization beam splitter and two intensity-modulators driven by a 10 Gb/s electrical timing recovery circuit. No error-rate floor is observed. >

Ultra-long distance wavelength-division-multiplexed soliton transmission using inhomogeneously broadened fiber amplifiers

The use of inhomogeneously broadened amplifiers for wavelength-division-multiplexed (WDM) optical soliton transmission is proposed. Dynamic gain equalization can be achieved through saturation, by adjustment of the time-averaged intensity of control lasers tuned between the WDM channels. The authors investigate numerically an example in which seven WDM channels at 2 Gb/s each are equalized using parameter values reasonable for germanosilicate core erbium-doped fibers. >

Optical soliton transmission

AbstractThis paper discusses the basic properties and advantages of optical solitons which are under investigation in many countries for the purpose of their application in realizing ultrahigh‐speed communications. Especially, the recent developments in erbium optical amplifiers, which are epochal in optical soliton transmission, have made soliton communication actually realizable. Here, the techniques of the so‐called dynamic soliton communication are considered and recent research is reported.

Ultra-Short Pulses for Optical Soliton Transmission. New Approach from External Modulation.

Mode-locking and gain-switching of semiconductor lasers have been reviewed from a view point of an optical short pulse generator for soliton transmission. A new approach from an external modulation using an electroabsorption modulator to generation of transform- limited optical short pulses is demon-strated. Transform-limited optical pulses up to 20 GHz repetition rates were generated just using a sinusoidal modulation of an InGaAsP electroabsorption modulator without any optical resonators and optical filters. The shape of the modulator-generated pulse is very closed to sech2 shape, and both the pulse width and the repetition rate can be easily varied by electrical signals. The promising future of the simple and stable optical pulse generation using the electroabsorption modulator was confirmed by 2.5 Gb/s-6400 km soliton data transmission using circulating loop experiments.

5 Gbit/s optical soliton transmission experiment over 3000 km employing 91 cascaded Er-doped fibre amplifier repeaters

5 Gbit/s modulated optical solitons were transmitted through a 3000 km optical fibre with 91 Er-doped fibre amplifiers. No error floor below 10−10 BER was observed and the measured power penalty at 10−9 BER was 1.4 dB. The effect of fibre chromatic dispersion on the transmission characteristics was also investigated.

32 Gb/s optical soliton data transmission over 90 km

The authors demonstrate error-free optical soliton transmission at 32 Gb/s over 90 km of dispersion-shifted fiber. Fiber loss was compensated for by using diode laser pumped Er/sup 3+/-doped fiber amplifiers located every 30 km and a 4 Gb/s data pattern was passively multiplexed to 32 Gb/s. Approximately 16-ps-wide, near transform-limited pulses were launched into the system and the output pulsewidth was about 14 ps. At the receiver, four-wave mixing was employed to perform all optical demultiplexing of the data down to the base data rate. At a 10/sup -9/ (2/sup 15/-1 word length) bit-error rate, the penalties from the demultiplexing and the 90-km soliton transmission were approximately 1.6 and 0.5 dB, respectively. >

Femtosecond soliton transmission in 18 km-long dispersion-shifted, distributed erbium-doped fibre amplifier

Femtosecond optical soliton transmission characteristics in a dispersion-shifted, distributed erbium-doped fibre amplifier as long as 18.2 km have been investigated. The erbium fibre has a dual shape core structure with a doping concentration of 0.5 ppm. Solitons (A = 0.7−1.2) with a pulse width of about 450 fs have been successfully transmitted, and even a slight narrowing was observed. When the soliton width was reduced to 260 fs, the output pulse width always broadened up to around 470 fs.

The optical soliton transmission amplified by bidirectional Raman pumps with nonconstant depletion

A numerical method to solve the coupled equations between the soliton and bidirectional Raman pump waves is proposed. The pump depletion due to the soliton is obtained without using the constant depletion approximation. With this method, the soliton propagation in a Raman-pumped fiber, can be solved accurately. It is found that the constant depletion approximation is valid at a small depletion rate, which requires low soliton power (or long pulsewidth), small material loss, and a short-pump period. In a periodically Raman-pumped fiber, there exists a stable signal energy which is very sensitive to the pump intensity. The stability of the soliton propagation with nonconstant pump depletion is studied. It is found that the stability predicted by the nonconstant depletion (NCD) and the constant depletion assumption (CDA) are generally different.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Automatic optical soliton control using cascaded Er 3+ -doped fibre amplifiers

Automatic amplitude control in an optical soliton transmission system is demonstrated for the first time using Er3+-doped fibre amplifiers and repeaters. After 250 km transmission, soliton pulses with consistent intensity and pulse width are obtained for a change in input signal level of 6 dB about the optimum value.

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

Optical soliton transmission of 5 Gb/s over a 23-km amplification spacing using a gain-switched 1.55- mu m distributed feedback laser diode and Ti:LiNbO/sub 3/ intensity modulator is discussed. An Er/sup +/-doped fiber amplifier, pumped by 1.45- and 1.48- mu m 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- mu m laser-diode pumping. A bit error rate (BER) of 2*10/sup -10/ has been obtained. >

Generation and transmission of optical solitons in the gigahertz region using a directly modulated distributed-feedback laser diode

We have succeeded for the first time, to our knowledge, in the generation and transmission of 6-24-GHz, 17-psec transform-limited solitons, using a directly modulated distributed-feedback laser diode with a narrow-band spectral filter and erbium-doped optical fiber amplifiers. The average optical power at 6 GHz from the erbium amplifier is greater than 10 mW, which corresponds to a peak power of 98 mW. The peak power is already in the soliton power regime for dispersion-shifted fibers. The solitons are transmitted over 22 km, and their original width can be completely preserved. The soliton-narrowing effect and high-order solitons that divide are also observed.

3.6 Gb/s all laser-diode optical soliton transmission

3.6-Gb/s optical soliton transmission using a gain-switched 1.55- mu m distributed-feedback laser diode and a Ti:LiNbO/sub 3/ intensity modulator is demonstrated. An Er/sup 3+/-doped fiber amplifier and a Raman amplifier, both pumped by 1.48- mu m 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.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Long-distance optical soliton transmission with lumped amplifiers

A soliton transmission method using lumped amplifiers is presented which is named the preemphasis method. An N=1 soliton with relatively high amplitudes (1.2<A<1.4), which is used as an input soliton, plays an important role in the lumped-gain soliton transmission system. The initial soliton pulse width can be preserved after propagation over long distance despite the existence of fiber loss. It is shown that with the lumped gain, the soliton pulse can propagate over more than 9000 km when the repeater spacing is 31 km and fiber loss is 0.22 dB/km.<<ETX>>