Manipulation of infrared dispersive waves in customized microstructured optical fibers for 1.7 and 2.0 µm light sources.

We demonstrate the controllable generation of infrared dispersive waves (DWs) from customized, in-house fabricated silica microstructured optical fibers (MOFs) by manipulating the location of zero dispersion wavelength (ZDW) through the structure of the fibers. The highly enriched shaping mechanism of arrested soliton in the MOFs with two ZDWs provides a technique for efficient energy transfer into the targeted eye-safe wavelengths at 1.7 and 2.0 µm by the virtue of DW formation.

Variational approach to study soliton dynamics in a passive fiber loop resonator with coherently driven phase-modulated external field.

We report a detailed semianalytical treatment to investigate the dynamics of a single cavity soliton (CS) and two copropagating CSs separately in a Kerr mediated passive optical fiber resonator which is driven by a phase-modulated pump. The perturbation is dealt with by introducing Rayleigh's dissipation function in the framework of a variational principle that results in a set of coupled ordinary differential equations describing the evolution of individual soliton parameters. We further derive closed-form expressions for quick estimation of the temporal trajectory, drift velocity, and the phase shift accumulated by the CS due to the externally modulated pump. We also extend the variational approach to solve a two-soliton interaction problem in the absence as well as in the presence of the externally modulated field. In the absence of a phase-modulated field, the two copropagating solitons can attract, repulse, or propagate independently depending on their initial delay. The final state of interaction can be predicted through a second-order differential equation which is derived by the variational method. While in the presence of the phase-modulated field, the two-soliton interaction can result in annihilation, merging, breathing, or a two-soliton state depending on the detuning frequency and the pump power. Variational treatment analytically predicts these states and portrays the related dynamics that agrees with the full numerical simulation carried out by solving the normalized Lugiato-Lefever equation. The results obtained through this variational approach will enrich the understanding of complex pulse dynamics under a phase-modulated driving field in passive dissipative systems.

Strong infrared radiation through passive dispersive wave generation and its control.

We observe strong infrared (IR) radiation as a result of passive dispersive wave generation for a realistic microstructured fiber having two zero-dispersion wavelengths. The IR radiation frequency can be suitably controlled by varying the operational wavelength, which falls in the first normal dispersion regime. The amplitude of the radiation can be significantly increased by introducing a suitable amount of chirp in the input pulse. This strong phase-matching radiation can be considered as an alternative solution for the IR laser for different applications.

Dynamics of Raman soliton during supercontinuum generation near the zero-dispersion wavelength of optical fibers.

We observe unique dynamics of Raman soliton during supercontinuum process when an input pulse experiences initially normal group-velocity dispersion with a negative dispersion slope. In this situation, the blue components of the spectrum form a Raman soliton that moves faster than the input pulse and eventually decelerates because of Raman-induced frequency downshifting. In the time domain, the soliton trajectory bends and becomes vertical when the Raman shift ceases to occur as the spectrum of Raman soliton approaches the zero dispersion point. Parts of the red components of the pulse spectrum are captured by the Raman soliton through cross-phase modulation and they travel with it. The influence of soliton order, input chirp and dispersion slope on the dynamics of Raman soliton is discussed thoroughly.

Generation of supercontinuum and its theoretical study in three-ring silica microstructured optical fibers.

We report supercontinuum generation in nonlinear microstructured optical fibers (MOFs) especially fabricated in a two-step stack and draw process having three rings of airholes. High air-filling fraction (>0.9) is obtained in a simple and straightforward way during the drawing process which is essential to enhance nonlinearity. Two of the fabricated samples are characterized and zero dispersion wavelength is tailored to achieve efficient pumping in the anomalous group velocity dispersion regime. The characteristics of the supercontinuum band as observed experimentally show good agreement with the predicted numerically simulated results, where soliton mediated dispersive waves are distinctly observed.

Effects of higher-order dispersion on resonant dispersive waves emitted by solitons.

Dispersive waves (DW) are generated owing to perturbation of solitons by higher-order dispersion (HOD) and nonlinearity during supercontinuum (SC) generation. The frequencies of these waves are governed by a phase-matching condition in the form of a polynomial whose coefficients depend on the numerical values of the properly normalized third- and HOD parameters. Our extensive numerical solutions show that all odd HOD terms generate a single peak on the blue or the red side of the carrier frequency, depending on the sign of the corresponding term. In contrast, positive even HOD terms create conjugate DW peaks, in both the blue and red sides. No radiation is observed for negative values of these parameters. The combination of all even and odd HOD coefficients may generate more than two DW peaks for some specific choice of parameters. The results predicted by the phase-matching condition agree well with extensive numerical simulations revealing interesting facts of SC generation.