Design rules for nonlinear spectral compression in optical fibers

Abstract

International audienceWe present comprehensive design rules to optimize the process of spectral compression arising from nonlinear pulse propagation in an optical fiber. Extensive numerical simulations are used to predict the performance characteristics of the process as well as to identify the optimal operational conditions within the space of system parameters. It is shown that the group-velocity dispersion of the fiber is not detrimental and, in fact, helps achieve optimum compression. We also demonstrate that near-transform-limited rectangular and parabolic pulses can be generated in the region of optimum compression

Impact of initial pulse shape on the nonlinear spectral compression in optical fibre

“…where z is the propagation distance, t is the reduced time, β2 is the group-velocity dispersion (GVD) With such parameters that are typical of various demonstrations of spectral compression due to SPM in fibre [12], the nonlinearity-dominant regime of propagation is applicable [17]. In this regime, the dispersion term in Eq.…”

“…1(a2). Note that the nonlinear propagation problem being studied can be conveniently normalized by introducing a normalized distance through the nonlinear length 1 /  P associated with the pulse at the entrance of the fibre [17,18].…”

“…However, several recent studies have demonstrated that the use of pre-shaped input pulses with a parabolic waveform can achieve spectral compression to the Fourier transform limit owing to the fact that for such pulses the cancellation of the linear and nonlinear phases can be made complete [15][16][17]. The purpose of this paper is to provide insight into the influence of the input temporal intensity profile on the spectral dynamics of negatively chirped pulses that occurs upon nonlinear propagation in a fibre.…”

Nonlinear sculpturing of optical pulses with normally dispersive fiber-based devices

“…According to the initial conditions of the input pulse, the initial stage of nonlinear dynamics in the fiber, where Kerr-induced self-phase modulation (SPM) dominates over GVD, may be very different. Indeed, input pulses with a negative chirp coefficient will experience spectral compression as a result of SPM [15,28,29], whereas for initially positively chirped (or Fourier transform-limited) pulses, spectral broadening will drive the nonlinear dynamics and eventually lead to optical wave-breaking [30]. Moreover, propagation in the nonlinear fiber is impacted by both GVD and SPM effects, which are characterized by the respective coefficients 2 and .…”

“…The region featuring low input powers (N below 2) and large propagated lengths corresponds to a long-term far-field evolution regime in the fiber characterized by the formation of pulses of a spectronic nature [20,21,46]. Finally, the region featuring anomalous input chirping and rather high input powers underpins nonlinear pulse dynamics dominated by a spectral compression process [29]. Figure 3 shows the temporal and spectral characteristics of the pulse generated at the point (C = −2, N = 5,  = 3).…”