Comparison of the Nonlinear Dynamic Pre- and Post-LED Equalization.

Visible Light Communications (VLC) have gained much popularity lately. In such a system, a white LED (Light-Emitting Diode) plays a double role as a light source and a transmitter. The main problem here is that the LED exhibits a low bandwidth and high nonlinearity, so the equalization of the LED nonlinear dynamic response is necessary.

Modeling of transmission characteristics in step-index polymer optical fiber using the matrix exponential method.

In this paper, we propose to calculate the impulse and frequency response of step-index polymer optical fiber in the presence of mode coupling using the matrix exponential method. The computation time in this method is independent of the fiber length and is typically 2 orders of magnitude shortened compared with the standard numerical procedures involving finite difference methods. Results obtained with our method are compared with those of known cases, where an analytical solution for the time-dependent power flow equation exists, and with a finite difference method.

Volterra Kernel Estimation of White Light LEDs in the Time Domain.

In this paper, we present a time domain method for extracting coefficients of nonlinear Volterra-series kernels for white light-emitting diodes (LED) used both for illumination and visible light communications. We show that this method may have several advantages over the thus far more popular frequency domain method. We successfully apply the measured kernel coefficients up to the 3rd order for the modeling of nonlinear distortion impact on advanced modulation formats: pulse amplitude modulation, carrierless amplitude phase and orthogonal frequency division multiplexing.

Carrierless amplitude phase modulation of VCSEL with 4 bit/s/Hz spectral efficiency for use in WDM-PON.

We experimentally demonstrate successful performance of VCSEL-based WDM link supporting advanced 16-level carrierless amplitude/phase modulation up to 1.25 Gbps, over 26 km SSMF with spectral efficiency of 4 bit/s/Hz for application in high capacity PONs.