A. A. Rieznik

Highly efficient generation of broadband cascaded four-wave mixing products

We propose a novel way to efficiently generate broadband cascaded Four-Wave Mixing (FWM) products. It consists of launching two strong pump waves near the zero-dispersion wavelength of a very short (of order a few meters) optical fiber. Simulations based on Split Step Fourier Method (SSFM) and experimental data demonstrate the efficiency of our new approach. Multiple FWM products have been investigated by using conventional fibers and ultra-flattened dispersion photonic crystal fibers (UFD-PCFs). Measured results present bandwidths of 300 nm with up to 118 FWM products. We have also demonstrated a flat bandwidth of 110 nm covering the C and L bands, with a small variation of only 1.2 dB between the powers of FWM products, has been achieved using highly nonlinear fibers (HNLFs). The use of UFD-PCFs has been shown interesting for improving the multiple FWM efficiency and reducing the separation between the pump wavelengths.

Uncertainty relation for the optimization of optical-fiber transmission systems simulations.

The mathematical inequality which in quantum mechanics gives rise to the uncertainty principle between two non commuting operators is used to develop a spatial step-size selection algorithm for the Split-Step Fourier Method (SSFM) for solving Generalized Non-Linear Schrödinger Equations (G-NLSEs). Numerical experiments are performed to analyze the efficiency of the method in modeling optical-fiber communications systems, showing its advantages relative to other algorithms.

Analytical solution for the dynamic behavior of erbium-doped fiber amplifiers with constant population inversion along the fiber

We present an analytical solution for the coupled rate and propagation equations for a dynamic two-level homogeneously broadened system interacting with radiation and with constant population inversion along the longitudinal axis of the fiber, z. We derive an analytical solution for the z dependence of these equations, which greatly simplifies the numerical solution for the output powers’ time dependence. Amplified spontaneous emission and background loss influences are considered in the model, in contrast to the previous analytical solution presented by Y. Sun et al. The solution is derived, and the importance of each term for the dynamic modeling of typical erbium-doped fiber amplifiers is analyzed.

Study on a new split-step Fourier algorithm for optical fiber transmission systems simulations

Recently we presented a new split-step Fourier algorithm to the simulation of optical-fiber transmission systems. To check it, we show here its efficiency to model a two first-order soliton collision, which is a situation of practical interest because of its sensitivity to numerical errors.

Accurate numerical simulation of short fiber optical parametric amplifiers

We improve the accuracy of numerical simulations for short fiber optical parametric amplifiers (OPAs). Instead of using the usual coarse-step method, we adopt a model for birefringence and dispersion which uses fine-step variations of the parameters. We also improve the split-step Fourier method by exactly treating the nonlinear ellipse rotation terms. We find that results obtained this way for two-pump OPAs can be significantly different from those obtained by using the usual coarse-step fiber model, and/or neglecting ellipse rotation terms.

Designing fiber dispersion for broadband parametric amplifiers

We present a method to determine the fiber chromatic dispersion curve that optimizes the gain bandwidth and ripple of fiber optical parametric amplifiers. We found that controlling high order dispersion terms a great enhancement of the gain spectrum is achieved. We provide a simulation example of a photonic crystal fiber, designed to control up to the sixth order dispersion parameter that gives 33 dB of gain from 1440 nm to 1600 nm, within 0.2 dB of gain variation.

Multiple four-wave mixing in ultra-flattened dispersion photonic crystal fibers

The generation of multiple four-wave mixing products in ultra-flattened dispersion photonic crystal fibers is presented. We obtained more than 200 products spanning over 170 nm by launching 3 lasers at ITU-T grid specification.

Black-box model for the complete characterization of the spectral gain and noise in semiconductor optical amplifiers

A Black Box Model for the quick complete characterization of the optical gain and amplified spontaneous emission noise in Semiconductor Optical Amplifiers is presented and verified experimentally. This model provides good accuracy, even neglecting third order terms in the spectral gain shift, and can provide cost reduction in SOA characterization and design as well as provide simple algorithms for hybrid integration in-package control.

Spontaneous decay rates in active waveguides.

We present a new method of measuring the guided, radiated, and total decay rates in uniform waveguides. It is also shown theoretically that large modifications of the total decay rate can be achieved in realistic erbium-doped fiber amplifiers and erbium-doped waveguide amplifiers with effective mode area radii smaller than approximately 1 microm.

Mitigating PMD in Fiber Optical Parametric Amplifiers With Alternating Fiber Twists

We show by means of analytical calculations and numerical simulations that the impact of polarization-mode dispersion (PMD) on the gain spectrum of fiber optical parametric amplifiers (OPAs) can be reduced by imposing twists along the fiber axis. Alternating twists are used in order to cancel the induced circular birefringence.