Infinite-distance soliton transmission with soliton controls in time and frequency domains

It is shown by computer runs and simple analysis that one hundred million km soliton transmission is possible by means of soliton transmission controls in the time and frequency domains. This means that limitless transmission is possible. The key to success is to reduce noise by the synchronous modulation technique which can also reduce timing jitter and nonlinear interaction forces. The accumulated noise converges to a fixed low level even after limitless transmission.<>     

Soliton transmission control in time and frequency domains

Soliton transmission control techniques in both the time and frequency domains designed to enable ultra-long-distance soliton transmission are described in detail. Soliton transmission control in the time domain, which can be realized by synchronous modulation, is a retiming technique which removes jitter and nonlinear interaction between adjacent solitons. In addition, a transfer function reduces noise and the noise power eventually converges to a low level for any transmission distance. Soliton transmission control in the frequency domain, which can be realized with a bandpass optical filter, stabilizes the soliton pulse. A million-kilometer transmission experiment confirms the usefulness of these techniques     

40 Gbit/s OTDM soliton transmission over transoceanic distances

40 Gbit/s soliton transmission is achieved in a recirculating loop over 10000 km, for the first time to the authors' knowledge. With a single carrier wavelength. Propagation has been tested with and without polarisation multiplexing thanks to low polarisation dependency electroabsorption modulators for in-line control and for the time demultiplexing receiver     

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     

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 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     

Experimental demonstration of a low-latency fiber soliton logicgate

We experimentally demonstrate switching in a 50 m-long soliton logic gate with a switching energy of 40 pJ using 490 fs pulses at 1.553 μm from an erbium-doped fiber laser. A full characterization of this gate shows a peak contrast ratio of 4.2:1, a timing window of 1.1 pulse width and cascadable operation. To our knowledge, the gate length of 50 m is at least six times shorter than other designs with comparable switching energies. The low-latency of this gate is possible due to a low-birefringent polarization-maintaining fiber that possesses a high polarization extinction ratio of up to 20 dB with a low birefringence of 2.6×10^-6. The low birefringence leads to a longer walk-off length between two orthogonally polarized pulses, where the walk-off length for 490 fs pulses is 56 m. We also study this gate numerically and find good agreement between the simulations and experiments     

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     

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     

Field demonstration of soliton transmission at 10 Gbit/s over 2000km in Tokyo metropolitan optical loop network

Experimental field transmissions of solitons at 10 Gbit/s over 2000 km have been successfully demonstrated using part of the Tokyo metropolitan optical loop network. The network is composed of conventional dispersion-shifted 200 core optical fibre cable which was not originally intended for soliton transmission. However, with the dispersion-allocated soliton transmission technique, an error-free 13 ps soliton data train was successfully transmitted over 2000 km. The power penalty at a BER of 10^-10 was 3.1 dB     

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     

光孤子传输控制方案的探讨

文章首先分析了光孤子通信系统的限制因素,包括光纤损耗、孤子间的相互作用、各种高阶效应以及参量随机变化等.然后在此基础上,讨论了光孤子通信系统的传输控制方案,并分析比较了这些方案的优缺点,对光孤子系统设计具有参考价值.     

光载射频信号在多模塑料光纤中的传输特性研究

实验研究了光载射频信号在多模塑料光纤(POF)中的传输特性,将24GHz的正弦波信号与1.5Gbt/s的数字信号进行混频后再通过光强度调制器产生双边带调制光信号,将双边带调制信号通过多模POF发送至接收机,在接收机转化为24GHz的射频信号。实验结果表明,这种双边带调制的光载波射频信号可以在多模POF中传输50m后而功率代价可以忽略不计。     

Simultaneous extrapolation in time and frequency domains usinghermite expansions

The time-domain response of a three-dimensional (3-D) conducting object is modeled as an associate hermite (AH) series expansion. Using the isomorphism of the AH function and its Fourier transform, the frequency-domain response can be expressed as a scaled version of the time domain expansion. Using early-time and low-frequency data, we demonstrate simultaneous expansion in both domains. This approach is attractive because expansions with only 10-20 terms give good extrapolation in both time and frequency domains. The computation involved is minimal with this method. In this paper, we have applied this technique to the problem of extrapolating the current on a scatterer being excited by a uniform plane wave. Five scatterers were considered-a plate, disk, sphere, cube, and cone     

Propagation of solitons in fibers with randomly varyingbirefringence: effects of soliton transmission control

Propagation of solitons in fibers with randomly varying birefringence is studied with and without including the effect of soliton transmission control. A simple expression for the decay of soliton energy due to the birefringence is derived, which will be useful in predicting soliton-pulse broadening in randomly birefringent fibers with their polarization-mode dispersion parameter specified. It is also shown that transmission control of solitons effectively removes dispersive radiations generated by the birefringence     

Advanced types of the sensitivity analysis in frequency and time domains

The majority of standard tools for computer-aided design can perform only limited types of the sensitivity analysis: Spice determines operating-point sensitivities, and SpectreRF contains a parametric sensitivity analysis that can be used for determining the phase noise, for example. In the paper, some new types of the sensitivity analysis in frequency and time domains are described. These types of the analysis are not implemented in the standard circuit simulators.In the frequency domain, a procedure for determining the sensitivities of the noise figure is suggested. First, an improvement of the method for computing the noise figure is presented, which incorporates necessary circuit matching and eliminates the subtraction of output noise from the load at each frequency. Second, a simple formula is derived for computing the sensitivities of the noise figure. The sensitivity analysis in the frequency domain is generally demonstrated by means of a distributed microwave amplifier. The application of the sensitivity analysis of the noise figure for improving the noise properties of a monolithic microwave amplifier is described.In the time domain, a new recurrent formula is derived for the sensitivity analysis that efficiently uses high-order expressions of the algorithm for implicit numerical integration. Since the chosen integration algorithm is more flexible than the more frequently used Gear's one, the suggested formula leads to more efficient procedure. The sensitivity analysis in the time domain is important for analyzing symmetrical microwave circuits, because their operating-point sensitivities are zero in principle. For this reason, the significance of the proposed method is demonstrated by an analysis of a symmetrical radio-frequency CMOS multiplier. As an unusual example of exploiting the method, a temperature sensitivity analysis of a power operational amplifier is described.     

Energy transfers and frequency shifts from three soliton collisionsin a multiplexed transmission line with periodic amplification

In this paper, we show that there can be four wave mixing between three solitons having different, but equally spaced, frequencies. While this does not happen with solitons in a uniform lossless fiber, we show that in a transmission line with loss and periodically placed amplifiers, it can happen. The spatial periodicity of the transmission line serves to phase match the four wave mixing of the three solitons. This results in permanent frequency shifts for two of the three solitons and energy exchanges between all three solitons     

Experimental demonstration of step-like dispersion profiling inoptical fibre for soliton pulse generation and compression

Generation of 100 GHz trains of 500-700 fs pulses using dual-frequency beat conversion in a step-like dispersion profiled fibre is reported. The authors believe that this is the first time the generation and compression of soliton pulses using such a fibre has been demonstrated. The fabrication of such fibre assemblies does not require any special facilities and relies only on conventional optical fibre technology. They believe that the use of profiling the fibre dispersion by fibre segments instead of continuously dispersion-decreasing fibre is not only possible but preferable in many applications