Soliton Switching Research Articles

Vector soliton switching by using the cascade connection of saturable absorbers

We have numerically studied the cascade connection of a nonlinear amplifying loop mirror and a length of birefringent fiber with two linear polarizers. This structure is shown to work as a vector soliton switch under certain conditions. After optimizing each structure separately, we show the improvement of the switching response when the cascade connection is used. It is also demonstrated that this design acts as a good intensity filter for vector soliton pulses.

Effects of third-order dispersion on soliton switching in fiber nonlinear directional couplers

The split-step Fourier method is used to study the energy switching characteristics of fiber nonlinear directional couplers with the third-order dispersion. The effects of the third-order dispersion increases with the third-order dispersion coefficient and input power and result in pulse shift and energy decreases. Adding high-order nonlinear can partly overcomes these effects.

Femtosecond-Soliton Switching in a Three-Core Coupler

Soliton switching in a three-core Kerr-coupler is studied numerically by taking into account intermodal dispersion (IMD), third-order dispersion and higher-order nonlinear effects, like the Raman and self-steepening effects. It is shown that the weak coupling regime is the most suitable for the purpose. Also, it is shown that IMD has negligible influence on switching, while, out of the higher-order nonlinear effects, Raman intrapulse scattering has the dominant effect.

Incoherent blocker soliton interactions in Kerr waveguide arrays

We have observed the incoherent interaction between a highly confined (blocker) soliton and wide, moving signal beams of a different wavelength in a one-dimensional discrete Kerr medium. Digital switching of the blocker solitons to successive adjacent channels was measured with increasing signal power via both one and two cascaded interactions in an AlGaAs waveguide array, operations equivalent to a reconfigurable three-output router.

Analytical and numerical studies of the performance of a nonlinear directional fiber coupler with periodically modulated dispersion

In this paper, we report numerical and analytical studies of the propagation of ultrashort optical soliton pulses in two-core nonlinear fiber couplers constructed with periodically modulated dispersion fiber (PMDF). Our simulations is taking into account different amplitude and frequency modulations. Using the technique developed by Anderson, we convert the coupled nonlinear Schrödinger equations (NLSEs) into a variational problem with a corresponding Lagrangian equations of motion for a finite number of degrees of freedom and obtain the switching characteristics of the device. The transmission characteristics, the critical energy, extinction ratio (Xratio), and the crosstalk level (Xtalk) for first order solitons were studied for low to high pump powers. The analytical and numerical procedure was compared. Comparing both techniques we can say that the analytical procedure (Lagrangian formulation) provide very good description of soliton switching in the PMDF coupler for pump energies below the critical energy of the coupler.

Polarization instability, steering, and switching of discrete vector solitons

We study the dynamics of discrete vector solitons in arrays of weakly coupled birefringent optical waveguides with cubic nonlinear response. We start with a modulational instability analysis, followed by approximate analytical solutions in the form of strongly localized modes. Next, we compute the effective Peierls-Nabarro potential for these modes and obtain the spatial average of the power transfer between both polarizations modes as a function of their relative phase. Finally, we combine the concepts of polarization mode instability with discreteness-induced beam trapping by the array, and demonstrate numerically the amplification of a weak signal by a strong pump of the other polarization, combined with simultaneous discretized all-optical switching.

Compression, splitting and switching of bright and dark solitons in nonlinear directional coupler

Abstract A detailed numerical simulation of the switching, compression and splitting characteristics of various solitary pulses (bright, grey and dark) are carried out by a direct solution of the associated coupled NLS equation. Important physical parameters of the out going pulse such as, intensity distribution, root mean square spatial and temporal width and chirp are calculated. Both the cases of symmetric and asymmetric couplers are considered. The important phenomenon of periodic power transfer from one channel to the other unfolds. The compression varies with the type of pulse launched in the initial channel. It is observed that the chirping of the initial pulse has an optimum value and it vary quite noticeably with the character of the pulse and couplers, symmetric and asymmetric.

All-optical switching and amplification of discrete vector solitons in nonlinear cubic birefringent waveguide arrays

We study all-optical switching based on the dynamic properties of discrete vector solitons in waveguide arrays. We employ the concept of polarization mode instability and demonstrate simultaneous switching and amplification of a weak signal by a strong pump of the opposite polarization.

Optical crosstalk in a periodically inhomogeneous nonlinear dispersion directional fiber coupler

We present a numerical investigation of the propagation and the switching of fundamental solitons in a two-core nonlinear fiber coupler constructed with periodically modulated dispersion fiber (PMDFC). Our simulations are taking into account different amplitude and frequency modulations of the PMDFC. The transmission characteristics, the critical energy, the compression factor, the crosstalk (Xtalk) and extinction ratio (Xratio) levels of the first order solitons were studied for low to high pump energies. It was observed that for low modulation frequencies, the augmentation of pump power leads to an increase of the critical energy and decrease of the transmission efficiency. For higher modulation frequencies the effect in the critical energy is minimum but at high pump powers the transmission is less efficient. The switched pulses are broader for low frequency and high amplitude of modulation. The Xtalk level is a decrease function with the increase of pump power, however it is getting worse with the augmentation of the amplitude of modulation. At higher frequencies, the increase of the amplitude modulation is leading the Xtalk to a minimum as a function of pump power. In summary, we have shown that the introduction of a periodically modulated dispersion profile is leading the nonlinear directional coupler to strong variations in the transmission efficiency, Xtalk and Xratio levels as a function of the modulation amplitude and frequency as well as pump energy.

Switching of discrete optical solitons in engineered waveguide arrays.

We demonstrate a simple concept for controlling nonlinear switching of discrete solitons in arrays of weakly coupled optical waveguides, for both cubic and quadratic nonlinear response. Based on the effective discrete nonlinear equations describing light propagation in the waveguide arrays in the tight-binding approximation, we demonstrate the key ideas of the array engineering by means of a steplike variation of the waveguide coupling. We demonstrate the digitized switching of a narrow input beam for up to 11 neighboring waveguides, in the case of the cubic nonlinearity, and up to 10 waveguides, in the case of the quadratic nonlinearity. We discuss our predictions in terms of the physics of the engineered Peierls-Nabarro (PN) potential experienced by strongly localized nonlinear modes in a lattice, and calculate the PN potential for the quadratic nonlinear array for the first time.

Spatial soliton switching in quasi-continuous optical arrays.

We report on the phenomenon of trapping and switching of one-dimensional spatial solitons in Kerr-type nonlinear media with transverse periodic modulation of the refractive index. The solitons slowly radiate upon propagation along the periodic structure and are finally trapped in one of its guiding channels. The position of the output channel can be varied by small changes in the launching angle.

Soliton switching in a Kerr coupler with coupling constant dispersion: a variational analysis

Soliton switching in a nonlinear directional coupler (NLDC) with Kerr nonlinearity and coupling constant dispersion (caused by intermodal dispersion between the symmetric and the anti-symmetric modes of the coupler) is studied using the well-known variational method. Switching characteristics are calculated and discussed. It is shown that the switching characteristics of the Kerr coupler for all the pulses, with pulse width ranging from 10 to 100 fs, are identical for a given value of the coupling coefficient. The effect of the coupling coefficient on the critical energy for switching is studied and discussed. The amplitude and pulse width variations inside the coupler are presented, discussed and compared with the result of our numerical calculation of soliton evolution inside the coupler.

Numerical Modeling of Solitons in a Low Birefringent Optical Fiber

A numerical investigation, based on the split-step Fourier transform algorithm of all optical switching of solitons in a low birefringent optical fiber is presented. The numerical algorithm is described in detail.

Controlled switching of discrete solitons in waveguide arrays.

We suggest an effective method for controlling nonlinear switching in arrays of weakly coupled optical waveguides. We demonstrate digitized switching of a narrow input beam for as many as 11 waveguides in the engineered waveguide arrays.

Switching of solitons in tunnel-coupled optical waveguides by a weak signal of a different frequency

Switching of solitons in tunnel-coupled optical waveguides by a weak signal of a different frequency

Influence of group-velocity mismatch on soliton switching in a nonlinear fibre coupler

In this work, the influence of group-velocity mismatch on soliton self-routing pulse switching in a nonlinear fibre coupler is discussed in detail by the use of both variational approach and numerical simulation. The results obtained show that the group-velocity mismatch leads to the relative displacement between the two orthogonal polarization modes, increase of the critical power and reduction of the elimination-light ratio. For sub-ps pulse, the influence cannot be neglected.

Influence of birefringence on soliton switching in a twin‐core fiber coupler

AbstractIn this paper, the effects of randomly varying birefringence on soliton switching in a twin‐core fiber coupler are discussed in detail by numerical simulation. The results obtained show that these effects on sub‐ps soliton switching cannot be neglected, they would degrade the quality of the coupler. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 502–506, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10649

Spatial solitons in semiconductor microresonators

We describe experiments showing the existence of spatial solitons in semiconductor microresonators. We describe the manipulation of such solitons in view of technical applications: switching solitons on and off by coherent, as well as incoherent light, reducing the light power necessary to sustain and switch a soliton by optical pumping, and the limit in which independent solitons become so strongly bound that they form a coherent hexagonal pattern, marking the maximum information storage density.

Short Optical Pulse Switching in Three-core Nonlinear Fiber Couplers

The propagation and switching of short optical pulses in a three-core nonlinear fiber coupler have been investigated with a variation method within the framework of the Lagrangian density formulation.The analytical solutions were directly obtained from the coupled nonlinear Schr?dinger equations.It is shown that the soliton switching behavior predicted by the present analytical method agrees well with the results from numerical analysis.In addition,the coupling length and the switching threshold of solitons in a nonlinear coupler were obtained.

Bistable soliton states and switching in doubly inhomogeneously doped fiber couplers

Switching between the bistable soliton states in a doubly and inhomogeneously doped fiber system is studied numerically. Both the cases of lossless as well as lossy couplers are considered. It is shown that both up-switching (from the low state to the high state) and down-switching (from the high state to the low state) of solitons between bistable states are realizable, if the amplification of the input soliton for up-switching and the extraction of energy from it for down-switching are suitably adjusted.