A versatile all-optical parity-time signal processing device using a Bragg grating induced using positive and negative Kerr-nonlinearity

The properties of gratings with Kerr nonlinearity and PT symmetry are investigated in this paper. The impact of the gain and loss saturation on the response of the grating is analysed for different input intensities and gain/loss parameters. Potential applications of these gratings as switches, logic gates and amplifiers are also shown

Constrained pre-equalization accounting for multi-path fading emulated using large RC networks: applications to wireless and photonics communications

Multi-path propagation is modelled assuming a multi-layer RC network with randomly allocated resistors and capacitors to represent the transmission medium. Due to frequency-selective attenuation, the waveforms associated with each propagation path incur path-dependent distortion. A pre-equalization procedure that takes into account the capabilities of the transmission source as well as the transmission properties of the medium is developed. The problem is cast within a Mixed Integer Linear Programming optimization framework that uses the developed nominal RC network model, with the excitation waveform customized to optimize signal fidelity from the transmitter to the receiver. The objective is to match a Gaussian pulse input accounting for frequency regions where there would be pronounced fading. Simulations are carried out with different network realizations in order to evaluate the sensitivity of the solution with respect to changes in the transmission medium mimicking the multi-path propagation. The proposed approach is of relevance where equalization techniques are difficult to implement. Applications are discussed within the context of emergent communication modalities across the EM spectrum such as light percolation as well as emergent indoor communications assuming various modulation protocols or UWB schemes as well as within the context of space division multiplexing

Unconditionally Stable Fundamental Alternating Direction Implicit FDTD Method for Dispersive Media

This chapter presents the formulation of novel unconditionally stable fundamental alternating direction implicit finite-difference time-domain (FADI-FDTD) method for dispersive media. A generalized formulation is provided, which is applicable for various dispersive models, such as Debye, Lorentz, Drude, and complex conjugate pole-residue pair models. The extension for full 3D dispersive media using novel FADI-FDTD method makes the resultant update equations much more concise and simpler than using conventional ADI-FDTD method. To demonstrate the application of novel FADI-FDTD method, the analysis of plasmonic waveguide using FADI-FDTD method is provided. The characteristics of a surface plasmon waveguides with Au (gold) and Ag (silver) metal cladding, modeled as combination of Drude-Lorentz dispersive media are analyzed. Further analysis of plasmonic waveguide grating filter is also considered.Accepted versio