Showing papers on "Polarization mode dispersion published in 1979"
TL;DR: Pulse spreading in a single-mode optical fiber is discussed taking into account the third-order dispersion term of the waveguide when the light source is modulated by a Gaussian pulse.
Abstract: Pulse spreading in a single-mode optical fiber is discussed taking into account the third-order dispersion term of the waveguide when the light source is modulated by a Gaussian pulse. A general expression for the pulse shape is analytically obtained, and an asymptotic approximation is used when the third-order dispersion term is small. It is also shown that the pulse width is no longer proportional to the guide length when the third-order dispersion term becomes large.
118 citations
TL;DR: This work uses Gloge's LP-mode approximation to compute the dispersion of the LP(0l) (HE(11)) mode by solving the eigenvalue equation taking dispersive properties of core and cladding materials into account, and finds large percentage deviations between D(m+w) - D( m) and D(w).
Abstract: Theoretical work on dispersion in single-mode fibers sometimes uses the assumption that waveguide dispersion Dw and material dispersion Dm are separate effects that contribute additively to the total amount of dispersion Dm+w. Using Gloge’s LP-mode approximation we compute the dispersion of the LP01 (HE11) mode by solving the eigenvalue equation taking dispersion of core and cladding materials into account. The dispersion of the LP01 mode is computed by numerical differentiation of the solution of the eigenvalue equation. The difference Dm+w − Dm is compared to waveguide dispersion Dw, which is computed by ignoring the dispersive properties of the core and cladding materials. We find large percentage deviations between Dm+w − Dm and Dw. The assumption of additivity of material and waveguide dispersion is thus not quite correct. However, because of the small contribution of waveguide dispersion to the total dispersion of the LP01 mode, even a large percentage error in the waveguide dispersion has little influence on the over-all dispersion of the LP01 mode.
44 citations
TL;DR: In this article, a detailed analysis of the complex expression for pulse dispersion can be arranged in three groups of terms which may be defined as composite material dispersion, waveguide dispersion and composite profile dispersion.
Abstract: A study of single-mode fibres shows that in the normal operating region the cladding has as much effect on the propagation constant as does the core. A detailed analysis shows that the complex expression for pulse dispersion can be arranged in three groups of terms which may be defined as composite material dispersion, waveguide dispersion and composite profile dispersion. The analysis has been applied to a fibre for which the material dispersion parameters are accurately known and it is found that zero total dispersion can be obtained at a wavelength which depends on the profile and the core diameter but may be selected within a range roughly 1.3-2µm. However, there are severe requirements on the control of core diameter and profile.
40 citations
TL;DR: In this paper, it is shown that mode dispersion depends on the first and second derivatives of the propagation constant, and that a different type of approximation may be more useful than the first derivative.
Abstract: A number of recent papers have discussed the mode dispersion in step-index, monomode fibres using formulae based on accurate approximations for the modal propagation constant. It is shown here that, since dispersion depends on the first and second derivatives of the propagation constant, the use of such formulae may often be invalid and that a different type of approximation may be more useful
32 citations
TL;DR: The cancellation between material and waveguide dispersions for weakly guiding single-mode step-index fibers has been analyzed to predict the optimum wavelength lambda(0) for zero first-order dispersion and the residual second-orders T.
Abstract: The cancellation between material and waveguide dispersions for weakly guiding single-mode step-index fibers has been analyzed to predict the optimum wavelength λ0 for zero first-order dispersion and the residual second-order dispersion T. Greater accuracy in our numerical calculation of waveguide dispersion results in significant change in λ0 and T compared to the previous work by another investigator. The dependence of λ0 and T on the normalized frequency and relative index difference has also been improved and extended numerically. Physical origin of this dependence is discussed; it is considered to be due to different optical power distributions between core and cladding for different constituent wavelengths within the spectral width of the source.
26 citations
TL;DR: Pulse spreading in a single-mode optical fiber is discussed taking into account the third-order dispersion term of the waveguide when an optical source with a finite spectral width is modulated by a Gaussian-shaped pulse.
Abstract: Pulse spreading in a single-mode optical fiber is discussed taking into account the third-order dispersion term of the waveguide when an optical source with a finite spectral width is modulated by a Gaussian-shaped pulse. Explicit forms for group velocity and pulse width are obtained taking into account both the optical source bandwidth and modulation bandwidth, and these are compared with those obtained by a simple theory. A condition is also made clear how small the second-order dispersion term has to be before the thirdorder dispersion term becomes important.
25 citations
TL;DR: A novel technique to measure the wavelength dispersion of optical fibers in the 0.8-1.6 microm range, where germanium avalanche photodiodes possess adequate quantum efficiency, is described.
Abstract: A novel technique to measure the wavelength dispersion of optical fibers in the 0.8-1.6 microm range, where germanium avalanche photodiodes possess adequate quantum efficiency, is described. Dispersion is defined as dtau/dlambda, which can safely be changed to the difference formula Deltatau/Deltalambda, when Deltalambda is small, where tau is the transit time of the wave and lambda is the light wavelength. A monochromatic light, whose amplitude is modulated by a sinusoidal baseband signal, is launched into the optical fiber. The phase of the sinusoidal baseband signal changes with the monochromatic light wavelength variation due to the dispersion of the fiber. The phase variation gives an accurate value of Deltatau. The wavelength dispersion is obtained directly from the values of both Deltatau and Deltalambda. Using this technique, the wavelength dispersion of a single mode optical fiber, for example, is measured in the single mode wavelength range from 0.92 to about 1.6 microm.
20 citations
TL;DR: The normalised frequency for zero waveguide dispersion of the HE11 mode, called VOD, is highly dependent on profile shape and the more the profile departs from a step, the greater the increase of VOD above the effective single-moded region until, for example, VOD becomes infinite for profiles that fall off at a rate greater than or equal to the parabola.
Abstract: The normalised frequency for zero waveguide dispersion of the HE11 mode, called VOD, is highly dependent on profile shape. The more the profile departs from a step, the greater the increase of VOD above the effective single-moded region until, for example, VOD becomes infinite for profiles that fall off at a rate greater than or equal to the parabola.
16 citations
TL;DR: In this paper, the effect of the waveguide structure on pulse-delay measurements of material dispersion in optical fibres is examined and it is shown that waveguide dispersion has only a small influence on the measured values and introduces an uncertainty in the wavelength of zero dispersion of order ± 3 nm.
Abstract: The effect of the waveguide structure on pulse-delay measurements of material dispersion in optical fibres is examined. It is shown that waveguide dispersion has only a small influence on the measured values and introduces an uncertainty in the wavelength of zero material dispersion of order ±3 nm.
6 citations