Evolution of femtosecond pulses in single-mode fibers having higher-order nonlinearity and dispersion

Soliton behavior for a generalized mixed nonlinear Schrödinger model with N-fold Darboux transformation

A spectral problem, the x-derivative part of which is a simple generalization of the standard Ablowitz-Kaup-Newell-Segur and Kaup-Newell spectral problems, is presented with its associated generalized mixed nonlinear Schrödinger (GMNLS) model. The N-fold Darboux transformation with multi-parameters for the spectral problem is constructed with the help of gauge transformation. According to the Darboux transformation, the solution of the GMNLS model is reduced to solving a linear algebraic system and two first-order ordinary differential equations. As an example of application, we list the modulus formulae of the envelope one- and two-soliton solutions. Note that our model is a generalized one with the inclusion of four coefficients (a, b, c, and d), which involves abundant NLS-type models such as the standard cubic NLS equation, the Gerdjikov-Ivanov equation, the Chen-Lee-Liu equation, the Kaup-Newell equation, and the mixed NLS of Wadati and/or Kundu, among others.

CEP stable 1.6 cycle laser pulses at 1.8 μm

By using the novel approach for pulse compression that combines spectral broadening in hollow-core fiber (HCF) with linear propagation in fused silica (FS), we generate 1.6 cycle 0.24 mJ laser pulses at 1.8 μm wavelength with a repetition rate of 1 kHz. These pulses are obtained with a white light seeded optical parametric amplifier (OPA) and shown to be passively carrier envelope phase (CEP) stable.

Soliton switching and multi-frequency generation in a nonlinear photonic crystal fiber coupler

Soliton switching in nonlinear directional couplers implemented in photonic crystal fibers (PCF) examined here. A vector finite element method (FEM) has been developed to precisely calculate the dispersion along with coupling length of the guided modes. The PCF coupler geometry was carefully designed so that it can support soliton pulses. Soliton switching is demonstrated numerically at 1.55 microm for 100 femto-second (fs) pulses. Our theoretical results explain some of the key spectral features previously observed in the experiment.

New types of solitary wave solutions for the higher order nonlinear Schrodinger equation

We present new types of solitary wave solutions for the higher order nonlinear Schrodinger (HNLS) equation describing propagation of femtosecond light pulses in an optical fiber under certain parametric conditions. Unlike the reported solitary wave solutions of the HNLS equation, the novel ones can describe bright and dark solitary wave properties in the same expressions and their amplitude may approach nonzero when the time variable approaches infinity. In addition, such solutions cannot exist in the nonlinear Schrodinger equation. Furthermore, we investigate the stability of these solitary waves under some initial pertubations by employing the numerical simulation methods.

Spectrotemporal measurement of picosecond pulses propagating in nonlinear single-mode fibers

The combined effects of positive group-velocity dispersion, self-phase modulation, and stimulated Raman scattering experienced by 85-psec pulses propagating along a 960-m-long single-mode fiber are experimentally studied. The use of a spectrograph followed by a streak camera provides measurements in the spectrotemporal domain of the induced frequency modulation of a pump pulse. As a result, optical wave breaking, depletion of the leading edge with symmetrical spectral broadening, and complex instantaneous frequency structures are observed when the peak power of the input pulse is gradually increased to 435 W. The experimental method is also adapted for single-shot event analysis.

Numerical and experimental comparison of spectral broadening of femtosecond optical asymmetric pulses in a monomode fiber

The experimental self-phase-modulation spectra of 55-fsec optical pulses after propagation along 11 mm of monomode fiber are compared with the computed spectra obtained by a numerical solution of the nonlinear wave-propagation equation. We discuss the relative importance of the pertinent additional terms (third-order-disperson, shock, and reflection terms) and the importance of an asymmetric profile of the input pulses. This asymmetry is found to be a dominant parameter in the self-phase-modulation process. No other physical effect must be used in order to explain the observed spectra, which agree well with the numerical data.