Comparison between theory and experiment of nonlinear propagation for a-few-cycle and ultrabroadband optical pulses in a fused-silica fiber

Abstract

Abstract-Wave-propagation equations, including effectively the second derivative in time under the condition of a small difference between the group and phase velocities and the first derivative in position in the group velocity coordinate, are derived based on the slowly evolving wave approximation. These can describe ultrabroadband optical pulse propagation with not only self-phase modulation (SPM), but also induced-phase modulation (IPM) in the monocycle regime in a fiber. It is shown that linear dispersion effects can be rigorously included in the numerical calculations. Calculations including SPM in a single-mode fused-silica fiber with the Raman effect are performed and compared with experimental results. Also, calculations including IPM in the fused-silica fiber are compared with experimental results. The effects of each term in the calculations on spectra are analyzed and it is shown that inclusion of the Raman effect and the dispersion of the effective core area is important for obtaining better agreement with experiments. It is shown that inclusion of more than third-order dispersion terms is necessary for calculations of monocycle pulse propagation.Index Terms-Nonlinear fiber optics, ultrabroadband and monocycle pulse propagation, self-and induced-phase modulation.

Comparison between Finite-Difference Time-Domain Method and Experimental Results for Femtosecond Laser Pulse Propagation

“…The spectrabroadening by the induced-phase modulation (IPM) is one of these methods. There have been some reports of experiments on ultrabroadband-pulse generation using IPM in a silica fiber (Xu et al, 1999), (Karasawa et al, 2001b), (Shibata et al, 2002), (Yamashita et al, 2004) and an Ar-gas-filled hollow fiber, (Karasawa et al, 2000b) and also on optical pulse compression by nonlinear chirp compensation. (Yamashita et al, 2004) For these experiments on generating few-optical-cycle pulses, characterizing the spectral phase of ultrabroadband pulses analytically as well as experimentally is very important.…”

Optical solitons from a photonic crystal fiber and their applications

“…1, such as higher-order dispersion terms, self-steepening terms, and the Raman term become important. If we use a slowly-evolving wave approximation (SEWA) instead of SVEA, the following propagation 202 Photonic Crystals -Introduction, Applications and Theory www.intechopen.com equation can be derived (Karasawa et al, 2001),…”

“…If we consider the electric field (considered to be scalar) that depends on only time t and propagation position z such that E(z, t)=Re [A(z, t)e i(β 0 z−ω 0 t) ],whereRe shows the real part, ω 0 is the central angular frequency, and β 0 is the propagation constant at ω 0 (β 0 = β(ω 0 )) of a pulse, the slowly varying envelope approximation (SVEA) equation for 10 www.intechopen.com the envelope A(z, t) (normalized to have the unit [W 1/2 ]) may be obtained from the Maxwell equation after various approximations (Karasawa et al, 2001) as follows,…”

Single Radial/Azimuthal Mode Photonic Crystal Fibers With Anisotropic Elliptical-Hole Lattice Core

“…The radius of cladding air hole is represented by R c . Considering the material dispersion of SiO 2 existing in the real applications, we calculate the refractive index of fused-silica based on the Sellmeier equation [15], which is expressed as follows:…”