Second-order Dispersion Effects Research Articles

Pure-quartic soliton attracted state and multi-soliton molecules in mode-locked fiber lasers

This article explores the dynamic model of pure-quartic solitons (PQSs) in mode-locked fiber lasers. Firstly, the formation and dynamic behavior of the PQS attracted state in fiber lasers are investigated to demonstrate their exceptional stability, robustness, and predictability. Next, the transmission characteristics of single PQS in mode-locked fiber lasers is subsequently analyzed and compared to those of solitons generated while considering the effect of second-order dispersion. Finally, the evolution of multi-PQS molecules is explored, and a stability analysis method for these soliton molecules is proposed. The findings of this research are not only significant for a deeper understanding of nonlinear interaction mechanisms but also contribute to the development of ultrafast optical devices and offer new insights into the understanding and application of complex nonlinear systems.

Effects of second-order dispersion of ultrashort laser pulse on stimulated Raman scattering

Abstract The influence of second-order dispersion (SOD) on stimulated Raman scattering (SRS) in the interaction of an ultrashort intense laser with plasma was investigated. More significant backward SRS was observed with the increase of the absolute value of SOD ( $\mid \kern-1pt\!{\psi}_2\!\kern-1pt\mid$ ). The integrated intensity of the scattered light is positively correlated to the driver laser pulse duration. Accompanied by the side SRS, filaments with different angles along the laser propagation direction were observed in the transverse shadowgraph. A model incorporating Landau damping and above-threshold ionization was developed to explain the SOD-dependent angular distribution of the filaments.

Properties of Optical Soliton in a Three Level Medium with Quintic Nonlinearity

Propagation characteristics of optical soliton in a three level atomic medium are analyzed by treating the material medium quantum mechanically, but the electromagnetic wave classically. Both the cubic and quintic components of the nonlinear polarization of the electromagnetic field are considered along with those generated due to the dipole formation of the material. A numerical simulation is carried out with the help of split-step technique. It is observed that the power of the pulse, distance of propagation and degree of dispersion are intimately related. The role of polarization due to the material is duely compensated by keeping higher order dispersive terms. In this connection we have seen that keeping the higher order dispersive terms, up to the eighth order, which is actually the phenomenon of continuum generation, results in a better form of the pulse. In our paper, we have analyzed the effects in both the cases, that is, including and excluding the quintic terms and in each case we have considered the effects of second-order dispersion (β2) as well as the higher order dispersion terms ( 8 2 j j β =

XPM-induced crosstalk with combined effect of 2OD and 3OD in SCM–WDM optical transmission link

In this paper, the XPM-induced crosstalk has been evaluated with combined effect of second order Dispersion (2OD) and third order Dispersion (3OD) in SCM–WDM optical transmission link for varied dispersion parameters in different modulation frequencies and transmission lengths. It has been observed that there is significant effect of 2OD and 3OD on the XPM-induced crosstalk in a SCM–WDM transmission link. It has been observed that XPM-induced crosstalk lies between (−54 to −30) to (−42 to −18) dB and (−54 to −28) to (−38 to 16) dB in the presence of combined effect of 2OD and 3OD respectively for dispersion varied from 5ps/nm/km to 20ps/nm/km. Hence it observed that there is exponent increase in XPM-induced crosstalk with the increase in different modulation frequencies and transmission lengths and as dispersion increases, XPM-induced crosstalk also increases.

Effects of Second Order Dispersion in Free Space Optical Communication

Effects of Second Order Dispersion in Free Space Optical Communication

Self-phase-modulation in submicron silicon-on-insulator photonic wires

We measure the transmission of ps-pulses through silicon-on-insulator submicron waveguides for excitation wavelengths between 1400 and 1650 nm and peak powers covering four orders of magnitude. Self-phase-modulation induced spectral broadening is found to be significant at coupled peak powers of even a few tens of mW. The nonlinear-index coefficient, extracted from the experimental data, is estimated as n(2) ~ 5*10(-18) m(2)/W at 1500 nm. The experimental results show good agreement with model calculations that take into account nonlinear phase shift, first- and second order dispersion, mode confinement, frequency dispersion of n(2), and dynamics of two-photon-absorption-generated free carriers. Comparison with theory indicates that an observed twofold increase of spectral broadening between 1400 and 1650 nm can be assigned to the dispersion of n(2) as well as first order- rather than second-order dispersion effects. The analysis of pulse broadening, spectral shift and transmission saturation allows estimating a power threshold for nonlinearity-induced signal impairment in nanophotonic devices.

Nonlinear dynamics of a pulse in an anisotropic medium with birefringence

The dynamics of a wave packet propagating in an anisotropic nonlinear optical fiber with strong linear coupling of the orthogonal components of the pulse is studied. The regimes of modulation instability and formation of soliton-like pulses are analyzed for different polarization angles of the incident light with allowance made for the first-and second-order dispersion effects and the nonlinear effects of self-and cross-modulation.

Supraluminal velocity of a pulse envelope maximum in amplifying optical fiber

Frequency-modulated Gaussian pulse propagation in an amplifying fiber is described within the framework of a linear model with an allowance for the second-order dispersion effects. It is demonstrated that the presence of an imaginary part in the group velocity dispersion parameter of the single-mode optical fiber with luminous gain leads to the possibility of the pulse envelope at a supraluminal velocity.

Linear dynamics of a Gaussian frequency-modulated pulse in a single-mode fiber with a complex refractive index

By using a frequency-modulated Gaussian pulse as an example, it is shown within the framework of the linear model taking into account the second-order dispersion effects that the presence of the imaginary part of the dispersion parameter of the group velocity substantially affects the pulse dynamics in a single-mode optical fiber with gain. Absorption insignificantly influences the dispersion characteristics of the fiber and its transformation properties. The possibility of the realization of “supercompression,” under which the pulse duration τp → 0, as well as of compression of a pulse without initial frequency modulation, is revealed. It is shown that in these fibers, the propagation of the pulse peak with a faster-than-light velocity and the wavefront reversal effect are possible.

Measurement of phase and amplitude error distributionsin InP-based arrayed-waveguidegrating multi/demultiplexers

The authors have measured the phase and amplitude error distributions in an InP-based arrayed-waveguide grating (AWG) multi/demultiplexer using Fourier transform spectroscopy and signal data processing. The signal data processing technique was based on wavenumber scale transformation and was applied to reduce the effect of second-order dispersion in a measured interferogram. The results reveal that the main origins of the crosstalk and dispersion in an InP-based AWG are random and slowly-varying phase errors, respectively.

Rigorous assessment of small-signal analysis for linear and dispersive optical communication systems operating near zero-dispersion wavelength

This paper presents a rigorous small-signal theory for linear single-mode fibers taking into account the first- and second-order fiber dispersion. From this theory, exact small signal intensity modulation (IM) and frequency modulation (FM) fiber transfer functions are presented. Exact expressions of the intensity and frequency noise spectra at fiber output due to laser noise taking into account all Langevin noise terms are also derived. Accurate numerical simulations of the IM and FM fiber transfer functions, and intensity and frequency noise spectra after linear transmission along single-mode fiber are compared with theoretical predictions and very good agreement is achieved. In addition, the theoretical predictions are compared with other author's results and the discrepancies are thoroughly explained. A new expression for the transmission distance which can lead to further significant reduction of intensity noise spectrum in systems using single-mode lasers with reduced linewidth enhancement factor is presented. The theoretical and simulation results show that the magnitude of the small-signal IM and FM fiber transfer functions, and the intensity and frequency noise spectra after linear single-mode fiber transmission are not affected by second-order fiber dispersion. The theory indicates that second-order fiber dispersion solely introduces delay distortion in the IM and PM fiber transfer functions. So, with linear transmission second-order dispersion effects on the intensity and frequency noise have proved to be irrelevant even for very long broad-band fiber systems.

Ultra-broadband and chirp-free frequency doubling in β-barium borate

A method is presented to render first- and second-order dispersion effects in second-harmonic generation in β-barium borate negligible in the bandwidth of 5 fs Ti:sapphire pulses.

Intensity and frequency noise transmission along singlemode fibre at zero-dispersion wavelength

A rigorous small-signal theory for linear and dispersive singlemode fibre communication systems operating at the zero-dispersion wavelength is presented. From this theory, the intensity and frequency noise transmission along the singlemode fibre is assessed. The new theory shows excellent consistency with accurate numerical simulations of intensity and frequency noise spectra after singlemode fibre transmission. Theoretical and simulation results show that fibre transmission at zero-dispersion wavelength leads to intensity and frequency noise spectra at fibre output, similar to intensity and frequency noise spectra, respectively, at the input to the fibre. Accordingly, at zero-dispersion wavelength, second-order dispersion effects on the intensity and frequency noise are irrelevant even for ultra-high bit rates and long-haul fibre links.

Analysis of Low-coherence Excitation of a Two-mode Fibre Waveguide in the Michelson Interferometer Configuration

Abstract Low-coherence excitation of a two-mode fibre waveguide that leads to a suppressed interference pattern at its exit face is analysed. The use of classical coherence formalism and guided modes field representation reveals that the principle of coherence modulation can be used, i.e., the optical path difference between guided modes that exceeds the source coherence length can be compensated in the Michelson interferometer configuration. General considerations presented here also show the role played by the effect of second-order dispersion which substantially affects the use of this new fibre waveguide interferometer configuration for sensing applications.

Dispersion-compensating single-mode fibers: efficient designs for first- and second-order compensation

Single-mode dispersion compensating fiber designs with absolute dispersion values of greater than 100 ps/(nm km) are described. A multiclad fiber with a triangular refractive-index profile in the core gives a dispersion of −250 ps/(nm km), resulting in a 15:1 compensation scheme. All fiber designs use only the fundamental LP01 mode for dispersion compensation and can account for first- and second-order dispersion effects.

Statistical theory of polarization dispersion in single mode fibers

An analytical characterization of polarization dispersion measurements is presented. The authors report the solution of Poole's stochastic dynamical equation for the evolution of the polarization dispersion vector with fiber length. The authors extend this to a more complete description by considering small, second-order dispersion effects through the frequency derivative of the dispersion vector. The complete analytical solution is seen to accord with what were originally empirically derived features of the joint probability distribution of the polarization dispersion vector and its frequency derivatives. Among the analytically determined properties are the Gaussian probability densities of the three components of the dispersion vector, and the hyperbolic secant (soliton shaped) probability densities of the components of the derivative of the dispersion vector.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Second-Order Electro-Optic Effect in Diamond

A second-order electro-optic effect has been observed in diamond. An order of magnitude is established for the appropriate second-order electro-optic coefficient of diamond. A linear effect, forbidden by symmetry, is also observed and attributed to random residual strains, an average estimate of which is obtained as 10−5 for the particular sample used in this experiment. Birefringence due to second-order dispersion effects is also discussed.