Search results
Results from the WOW.Com Content Network
The group delay and phase delay properties of a linear time-invariant (LTI) system are functions of frequency, giving the time from when a frequency component of a time varying physical quantity—for example a voltage signal—appears at the LTI system input, to the time when a copy of that same frequency component—perhaps of a different physical phenomenon—appears at the LTI system output.
A closely related yet independent quantity is the group-delay dispersion (GDD), defined such that group-velocity dispersion is the group-delay dispersion per unit length. GDD is commonly used as a parameter in characterizing layered mirrors, where the group-velocity dispersion is not particularly well-defined, yet the chirp induced after ...
Group-velocity dispersion is quantified as the derivative of the reciprocal of the group velocity with respect to angular frequency, which results in group-velocity dispersion = d 2 k/dω 2. If a light pulse is propagated through a material with positive group-velocity dispersion, then the shorter-wavelength components travel slower than the ...
Consequently, for frequencies within the sweep range of the chirp, it is the square-law phase term Φ 1(ω) and its group delay function ( = -d Φ 1/d(ω) ) that are of most interest. There is a plot of the group delay shown below. Both this function and the phase Φ 1(ω) are independent of the value of the time-bandwidth product.
Experiments have been carried out to analyse the effect of high frequency (20 MHz-1 GHz) external magnetic field induced nonlinear Kerr effect on Single mode optical fibre of considerable length (50–100 m) to compensate group velocity dispersion (GVD) and subsequent evolution of soliton pulse ( peak energy, narrow, secant hyperbolic pulse). [18]
The introduced dispersion by such a compressor is often described in dispersion orders: the group delay dispersion (GGD), third order of dispersion (TOD) etc. Figure 2 shows the dispersion orders for a grating compressor with a groove density of = /, an incidence angle of =, and a normal grating separation of =, as described in the original ...
For a sufficiently large delay (from 10 to 1000 times the Fourier transform limited [FTL] pulse duration), the interference of the two time-delayed fields results in a cosine modulation with a nominal spacing of /; and any dispersion of the pulse results in minor deviations in the nominal fringe spacing. Effectively it is these deviations in ...
Given the dispersion relation, one can calculate the frequency-dependent phase velocity and group velocity of each sinusoidal component of a wave in the medium, as a function of frequency. In addition to the geometry-dependent and material-dependent dispersion relations, the overarching Kramers–Kronig relations describe the frequency ...