Phase Conjugation Using Four-Wave Mixing in Fast Green FCF Dye-Doped Gelatin Film

We present optical phase conjugation based on the degenerate four-wave mixing (DFWM) arrangement in gelatin films doped with acid blue 3 dye (FAST GREEN FCF) using He-Ne laser of total power 50 mW. Various parameters which influence the phase-conjugate (PC) signal during the DFWM process were studied (angle of between the forward pump and the probe beam, transition of gelatin film, reflectivity as a function of forward and backward beam). A maximum phase-conjugate beam reflectivity of about 0.02% has been observed in these dye-doped gelatin films. PACS: 42.65.-k, 42.65.Hw.

Localized Waves in Optical Systems with Periodic Dispersion and Nonlinearity Management

We overview our recent developments in the theory of dispersion-managed (DM) solitons within the context of optical applications. First, we present a class of localized solutions with a period multiple to that of the standard DM soliton in the nonlinear Schrödinger equation with periodic variations of the dispersion. In the framework of a reduced ordinary differential equation-based model, we discuss the key features of these structures, such as a smaller energy compared to traditional DM solitons with the same temporal width. Next, we present new results on dissipative DM solitons, which occur in the context of mode-locked lasers. By means of numerical simulations and a reduced variational model of the complex Ginzburg-Landau equation, we analyze the influence of the different dissipative processes that take place in a laser.

Localized States in Bi-Pattern Systems

We present a unifying description of localized states observed in systems with coexistence of two spatially periodic states, calledbi-pattern systems. Localized states are pinned over an underlying lattice that is either a self-organized pattern spontaneously generated by the system itself, or a periodic grid created by a spatial forcing. We show that localized states are generic and require only the coexistence of two spatially periodic states. Experimentally, these states have been observed in a nonlinear optical system. At the onset of the spatial bifurcation, a forced one-dimensional amplitude equation is derived for the critical modes, which accounts for the appearance of localized states. By numerical simulations, we show that localized structures persist on two-dimensional systems and exhibit different shapes depending on the symmetry of the supporting patterns.

Parabolic Pulse Generation Using Tapered Microstructured Optical Fibres

This paper presents a numerical study of parabolic pulse generation in tapered microstructured optical fibres (MOFs). Based on our results and the algorithms presented, one can determine the linear taper profile (starting and finishing pitch values and taper length) needed to achieve parabolic pulse shaping of an initial Gaussian pulse shape with different widths and powers. We quantify the evolution of the parabolic pulse using the misfit parameter and show that it is possible to reach values significantly better than those obtained by a step index fibre.

Analysis of High Birefringence of Four Types of Photonic Crystal Fiber by Combining Circular and Elliptical Air Holes in Fiber Cladding

This paper presents a numerical study of high birefringence induced by four types (Type 1–4) of different sizes of elliptical air holes in photonic crystal fibers (PCFs). The numerical simulation is carried out by using the finite element method. The statistical correlations between the birefringence and the various parameters are obtained. Based on our results, the birefringence is found to be largely dependent on the variation of the normalized frequency, size ratio, effective area of the circular and elliptical air holes, and the ring number of cladding. Two of our suggested structures, Type 1 and Type 3, can considerably enhance the birefringence in PCFs leading to values as high as7.697×10−3and8.002×10−3, respectively, which are much higher than that obtained by a conventional step-index fiber.