Statistical approach to end-to-end dispersion budgeting in single-mode fiber links using multilongitudinal-mode lasers

This paper presents a statistical analysis to the end-to-end chromatic dispersion budgeting in single-mode fiber links which employ multilongitudinal-mode laser transmitters around 1.3 or 1.55 μm regions. This is a novel approach which is relevant for upgrading the "bit rate × distance" of those already installed 400- and 565-Mbit/s fiber links.     

Attenuation and bit-rate limitations in LED/single-mode fibertransmission systems

In this analysis, distortion of the spectral distribution of the light due to the wavelength dependence of the loss in the fiber is taken into account. The computations show that the system performance of a given fiber type may be characterized by three parameters, one for attenuation and two for dispersion. The attenuation in the fiber may be modeled by an average attenuation per unit length, whereas the bit rate that limits the sensitivity degradation in the receiver due to intersymbol interference to less than 1 dB may be modeled by a bit-rate distance product and a constant bit rate valid for long lengths of fiber. As a design aid in system planning, diagrams showing the three parameters as functions of the diode center wavelength and the spectral width for typical single-mode fibers have been prepared     

Triple-clad single-mode fibers for dispersion shifting

A design procedure for triple-clad dispersion-shifted single-mode fibers is developed. Following this procedure, fibers are identified which have low dopant concentrations in the core compared to those of the previous dispersion-shifted fiber designs, a second-mode cutoff wavelength close to the operating wavelength, zero dispersion at 1550 nm, a small bending loss at 1550 nm (for a bend radius of 3.75 cm), and a spot size that is large enough not to compromise the splice loss. A significant advantage of these fibers is that low-dispersion is available over a wide wavelength band about the wavelength of zero dispersion     

Statistical distribution of polarization-dependent loss in thepresence of polarization-mode dispersion in single-mode fibers

The statistical distribution of polarization-dependent loss in single-mode fibers is studied via Monte-Carlo simulations. In the presence of polarization-mode dispersion, it is found that the probability density function of polarization-dependent loss is a combination of Rayleigh and Maxwell distributions     

New measurement method for polarisation dispersion in single-mode fibres employing frequency-modulated optical signal

A new measurement method for polarisation dispersion in a single-mode fibre, utilising the coherence property of frequency-modulated laser diode light, is proposed. Polarisation dispersion is determined exactly by selecting the modulation condition which gives depolarisation light at the fibre end.     

Zero-mode dispersion in single-mode fibres

Near cutoff the loss of the LP11-mode in cladded optical fibres becomes very high in the presence of even slight bends. Singlemode operation can thus be achieved with zero-mode dispersion as well as zero material dispersion, thus promising enormously large bandwidths.     

Statistical characteristics and effects of polarization mode dispersion in dispersion managed soliton systems

Recently,the dispersion-managed solitons(DMS) areof great interest in soliton communication systems .Be-cause of some prior advantages compared with conven-tional solitons ,such as higher pulse energy and signalnoise ratio,lower averaged dispersionline an…     

Wavelength dispersion in a single-mode fibre

Wavelength dispersion in a single-mode fibre has been evaluated by measuring propagation times of various-wavelength pulses transmitted through a 3.72 km-length fibre. Dispersion in a single-mode fibre is dominated by material dispersion, and is estimated to be 9.1 ps/? dkm at 0.85 ?m wavelength.     

Technique for direct measurement of single-mode fiber chromatic dispersion

A technique for the direct measurement of single-mode fiber chromatic dispersion is presented. The technique uses wavelength modulation to provide a differential fiber chromatic delay signal from which chromatic dispersion is obtained directly. The system is described in detail and practical measurement results shown to illustrate the high accuracy of the technique and its versatility in use with all fiber types.     

System penalty effects caused by spectral variations and chromatic dispersion in single-mode fiber-optic systems

Optical submarine systems are now being planned, and because of the need for high levels of confidence in such systems, all aspects that affect performance need detailed investigation. Of particular importance are penalties that may arise from spectral effects. A theoretical and practical examination has been made of the relationship between source spectrum and system performance in the presence of chromatic dispersion. Equipment is described which provides an automatic record of the power budget penalty resulting from spectral variations for all temperatures in the operating range. Significant differences are found, even between lasers of the same type. The nature of the corresponding spectral differences is studied, and evidence is presented to show that both random and regular variations exert appreciable effects.     

New method for measuring the chromatic dispersion of installed single-mode fibers utilizing wavelength division multiplexing techniques

This paper describes a novel method designed to measure the chromatic dispersion of installed single-mode fiber cables. The systems developed utilize the modulation phase/multiple laser diode techniques; however, by the addition of wavelength division multiplexing, the reference laser and fiber was eliminated. Laboratory and field results for measured wavelength ranges of 1200-1330 and 1200-1550 nm are presented.     

Chromatic dispersion in single-mode fibers with arbitrary indexprofiles: a simple method for exact numerical evaluation

An exact numerical method for computation of the chromatic dispersion in single-mode fibers with arbitrary profiles is presented. The method is based on matrix perturbation theory, taking the change in the fiber properties with wavelength as perturbation. This approach requires only one matrix eigenvalue evaluation (as against multiple eigenvalue evaluations in the existing methods) and a few additional simple matrix manipulations, resulting in a considerable reduction of computational effort     

Minimum dispersion at 1.55 ?m for single-mode step-index fibres

The single-mode step-index fibre parameters, relative index difference and core diameter, have been predicted to achieve first-order cancellation between material and waveguide dispersions at 1.55 ?m. Our prediction by accurate solution of the characteristic equation results in fibre parameters different from those obtained by other investigators. The origin of this difference is examined.     

Zero total dispersion in graded-index single-mode fibres

The combined effects of composite material dispersion, profile and waveguide dispersion can be made zero at a wavelength which depends on core diameter, refractive-index profile and composition. Wide bandwidths over large repeater spacings are therefore possible although close fabrication tolerances may be required.     

Field to dispersion relationships in single-mode fibres

Exact explicit expressions are obtained which relate (i) the modal spotsize and (ii) the core power to the dispersion parameters in single-mode optical fibres. Spotsize can therefore be expressed exactly in terms of the core power, with the degree of guidance playing a crucial role in the relationship.     

Soliton technique to characterize single-mode fiber dispersion

Transmitting subpicosecond pulses at moderate powers over a few meters of fiber creates a notch in the pulses' power spectra in the vicinity of the fiber's zero-dispersion wavelength. This is caused by the interaction of nonlinear self-phase modulation and third-order dispersion. This phenomenon can be used to determine the zero-dispersion wavelength of single-mode fibers     

Pulse dispersion for single-mode operation of multimode cladded optical fibres

Pulse dispersions as low as 0.4 ns/km have been measured in multimode cladded fibres at a normalised frequency V=125 and for a constant bend radius of 5.5 cm. Particularly when the number of launched modes is small, the pulse dispersion, as well as the polarisation and angular width of the output beam, are strong functions of the degree of mode conversion.     

Improved all optical chromatic dispersion monitoring method for WDM systems

In this paper we propose an improved all optical chromatic dispersion (CD) monitoring method applicable to wavelength division multiplexing (WDM) systems with intensity or phase modulation format. This method can operate over a much larger bandwidth and CD monitoring range and is insensitive to optical signal-to-noise ratio (OSNR) and polarization mode dispersion (PMD). These improvements are achieved by utilizing a wavelength tunable laser as the probe to maintain the appropriate phase-matching condition and a loop-back controlled tunable CD compensator to discriminate CD distortions from PMD and OSNR influences. Numerical simulations show that by this method the operational bandwidth and CD monitoring range can be expanded to cover C + L bands and ±1600 ps/nm, respectively, for different modulation formats and the sensitivity is higher than the other methods proposed before.     

Energy enhancement of dispersion-managed solitons in optical fibertransmission systems with lumped amplifiers

We simulated dispersion-managed soliton propagation in optical fiber transmission systems with lumped amplifiers and loss. The energy enhancement of dispersion-managed solitons can be more or less than in the lossless case, depending delicately on the amplifiers arrangement. In all cases, there is a maximum enhancement factor beyond which the dispersion-managed soliton no longer exists and which also depends delicately on the arrangement     

Prediction of mode dispersion in graded-index single-mode fibres

A Cheby?shev power series method is presented for the calculation of the propagation constant of graded-index fibres. Accurate predictions of the dispersion parameters can be obtained as shown by examples of step and parabolic profiles. Measured index profiles can also be used with local index values found by linear interpolation from nearest reading points. Examples are given to demonstrate the effectiveness of this approach.