Fiber Analysis & Design

Effects of Group Velocity Dispersion (GVD) on Gaussian Pulse Propagation

To demonstrate the influence of the group (GVD) velocity dispersion on pulse propagation in optical fibers in “linear” regime. The basic effects related to GVD are: GVD induced pulse broadening GVD induced pulse chirping Pulse compression  The equation, which describes the effect of GVD on optical pulse propagation neglecting the losses and nonlinearities, is [1]:   where…

Effects of PMD on Pulse Propagation

Polarization mode dispersion (PMD) can cause serious problems in high bit-rate transmissions. In this lesson, the PMD emulator component is used to demonstrate the distortions in the transmitted signal, caused by first and second order PMD effects. The system showed in Figure 1 is utilized in the simulations.  Figure 1: PMD system layout  The system simulates the…

Effects of Cross Phase Modulation (XPM) and Four-Wave Mixing (FWM)

The purpose of this lesson is to give an idea about the effects associated with cross-phase modulation (XPM) and four-wave mixing (FWM) accompanying the propagation of optical signals at different carrier frequencies in a nonlinear dispersive fiber [1]. At first, we create the layout shown in Figure 1. The Numeric tab of the Nonlinear Dispersive Fiber…

Combined Effects of GVD and SPM on Gaussian Pulse Propagation

This lesson demonstrates that the effects of SPM and anomalous GVD on the pulse propagation are counteracting. As already discussed, (see the “Group velocity dispersion” in the Tutorials), the effect of GVD on the pulse propagation depends on whether or not the pulse is chirped. With the proper relation between the initial chirp and the GVD…

Combined Effects of GVD and SPM on Modulational Instability

This lesson demonstrates that the propagation of a CW beam inside an optical fiber is inherently unstable due to the interplay between the anomalous GVD and SPM. The layout and the parameters are shown in Figure 1.   Figure 1: Layout and parameters  The CW Laser is used as a pump source (Figure 2). Its “Linewidth” is set…

PMD-Induced Broadening of Ultra-Short Pulses

This lesson demonstrates the broadening of a “very short” (Dirac δ-shaped) pulse caused by polarization mode dispersion (PMD). It also shows that the probability distribution function of the differential group delays between the principal states of polarization generated by the component agrees well with the Maxwellian one. The “coarse step” method [4], [5] with fiber segments…

Validation of FWM Effect

This tutorial demonstrates the validity of the FWM algorithm, as well as providing the user with some useful designing tips for optimizing simulation time and accuracy. The layout in was used to obtain results, and can be found in the sample file FWM Validation.osd  Figure 1: FWM project layout  In the two CW Lasers, the frequencies are set…

Stimulated Raman Scattering

This lesson demonstrates the light amplification caused by the stimulated Raman scattering effect. The layout and its global parameters are shown in Figure 1.   Figure 1: Layout and global parameters  Figure 2 shows the setup for the optical fiber component.    Figure 2: Setup parameters  The spectrum of the input signal consists of a strong pump monochromatic wave…

Stimulated Raman Scattering—Separated Channels

The purpose of this lesson is to demonstrate light amplification resulting from the stimulated Raman scattering effect. The layout with its global parameters is shown in Figure 1   Figure 1: Layout and global parameters  The input spectrum (Figure 2) consists of a strong (pump) wave at 193 THz (100W) and four weak (probe) waves at frequencies 188…

SPM-Induced Spectral Broadening

This lesson demonstrates the basic effects of self-phase modulation (SPM) on pulse propagation. These include: Pulse chirping Pulse spectral broadening  The effects SPM of are described by [1]:where E(z, t) is the electric field envelope, and the parameter y is given by: In Equation 2, ω0 is the carrier (or reference) frequency, n2 is the nonlinear-index…