We numerically examine the dynamics of stimulated Raman scattering combined with self-phase modulation for intense 100-psec-long input pulses in a dispersive single-mode optical fiber. Linear dispersion is treated in a first-order approximation by introducing group-velocity mismatch between pump and Stokes pulses. It is shown how this mismatch combined with pump depletion leads to asymmetric distortions of both pulse shapes and frequency chirps. The resulting delay of the Stokes peak is found to reach higher values for lower input pump powers. For sufficiently long fibers the emerging pump pulse has a one-peak structure, in contrast to the two-peak structure in the dispersionless case. The existence of an optimum fiber length to obtain the shortest Stokes pulse for a given input pulse is shown.

Numerical study on combined stimulated Raman scattering and self-phase modulation in optical fibers influenced by walk-off between pump and Stokes pulses

A numerical study is presented on the frequency chirp and spectra of light pulses affected by both self-phase modulation and stimulated Raman scattering in optical fibers. The asymmetric distortion of pump and Stokes spectra is attributed to walk-off between the pulses and found to be in good agreement with recent experimental results. The stationary-phase method is employed to explain the relation between the structure of the spectra and the form of the pulse chirp. An analytic expression describing the chirp of a depletable pump and of the first Stokes pulse is given for negligible walk-off. The dominant influence of self-phase modulation over the cross phase modulation on the buildup of the chirp in the case of large walk-off and severe pump depletion is shown.

Frequency chirp and spectra due to self-phase modulation and stimulated Raman scattering influenced by pulse walk-off in optical fibers

2014 The effects of self, induced, and cross phase modulations on the generation of picosecond and femtosecond « white » laser pulses are reviewed. Recent measurements of cross and induced phase modulations are reported using femtosecond and picosecond laser pulses. Revue Phys. Appl. 22 (1987) -1694 DÉCEMBRE 1987, PAGE 1677

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Effects of self, induced and cross phase modulations on the generation of picosecond and femtosecond white light supercontinua

This article reviews the current state-of-the-art of optical pulse compressors based on the optical fibre-grating pair. As this technique has become a standard laboratory procedure providing pulses with duration shorter than those directly generated from mode-locked lasers, we review the basic mechanism of the method, the role played by additional non-linear effects (such as stimulated Raman scattering), describe the current results, with emphasis to our own work, and point out the limitations of the technique.

Optical fibre-grating pulse compressors

It is shown that the process of forward stimulated Raman scattering in a single-mode fiber, which involves the pump pulse and the first Stokes wave, is an exactly soluble problem, provided that the temporal duration of these waves is sufficiently long. The analysis takes into account the effects of pulse walkoff arising from the dispersion of the fiber as well as self- and cross-phase modulation. The procedure is applied to two examples: the first is that of stimulated Raman scattering as it builds up from spontaneous Raman emission; the second is that of launching pump and Stokes pulses. >

Theory of stimulated Raman scattering in optical fibers in the pulse walkoff regime

A theory on combined self-phase modulation (SPM) and stimulated Raman scattering (SRS) in optical fibres is given. The theory shows that Raman frequency conversion is not affected by SPM, and the phase shifts of pump and Stokes radiation are proportional to the input pump pulse. The variation of the linewidths Δν1/2 of pump and Stokes pulses against pump peak powerPp is analysed numerically by fast Fourier transformation (FFT). The results show that the SRS has a small effect on the linewidth of pump light whenPp is small, and will saturate the increase in Δν1/2 asPp becomes large. Discussion on output pump pulse shape makes the physical meaning of the variation of Δν1/2 clear.

On combined self-phase modulation and stimulated Raman scattering in optical fibres

In the square-wave PFM system for transmission of TV programmes through optical fibres, square-wave PFM pulses are generated at the transmitter with a relatively low centre frequency, whereas double-frequency equal-width narrow pulses are produced in the receiver before the demodulating low-pass filter, at both the rising and falling edges of the transmitted pulses. The use of the frequency-doubling technique in such a system results in narrow transmission bandwidth and high receiver sensitivity, thus prolonging the transmission distance significantly as compared with ordinary PFM. In the experiment, the system is operated at 1.3 μm with multimode fibre having bandwidth 700 MHz km, a laser diode as optical source and a PIN/FET as detector. It can effectively transmit the high-quality broadcast TV programme with accompanying sound channel to a distance of 50.7 km. Experimental results are: receiver sensitivity −40 dB m, weighted SNR for video 59.3 dB, differential gain and differential phase less than 1% and 1°, respectively.

Frequency-doubling PFM system to prolong the distance of optical fibre TV programme transmission

Since the advent of computer communication networks, there have been considerable advances in the field of OSI network management. When there are a number-of subsystems operating and manipulating many complex jobs interconnected by a networks, the need for a network management facility is essential. The network management system is based on the ISO standards for OSI management. It is concerned primarily with the management of the communication subsystems in each node connected to an OSI network. The developed system does not attempt to implement all the management functions, but rather shows how the framework can be used to provide these functions. The ISO network management framework, based on the ISO basic reference model, has been defined to provide the means for the communication subsystems in all the nodes connected to a network to be remotely monitored and controlled. The paper describes the concepts development and achievements of our project in the field of OSI network management, which are applied to the project "optical fiber integrated services ring for Shanghai petrochemical complex".

http://ieeexplore.ieee.org/iel3/3836/11201/00545205.pdf

Li Yu-Lin

Papers

On combined self-phase modulation and stimulated Raman scattering in optical fibres

Frequency-doubling PFM system to prolong the distance of optical fibre TV programme transmission

An implementation of an open network management system