In an effort to reduce greenhouse gas emissions, experts are looking to substitute fossil fuel energy with renewable energy for environmentally sustainable and emission free societies. This paper presents the hybridization of particle swarm optimization (PSO) with grey wolf optimization (GWO), namely a hybrid PSO-GWO algorithm for the solution of optimal power flow (OPF) problems integrated with stochastic solar photovoltaics (SPV) and wind turbines (WT) to enhance global search capabilities towards an optimal solution. A solution approach is used in which SPV and WT output powers are estimated using lognormal and Weibull probability distribution functions respectively, after simulation of 8000 Monte Carlo scenarios. The control variables include the forecast real power generation of SPV and WT, real power of thermal generators except slack-bus, and voltages of all voltage generation buses. The total generation cost of the system is considered the main objective function to be optimized, including the penalty and reserve cost for underestimation and overestimation of SPV and WT, respectively. The proposed solution approach for OPF problems is verified on the modified IEEE 30 bus test system. The performance and robustness of the proposed hybrid PSO-GWO algorithm in solving the OPF problem is assessed by comparing the results with five other metaheuristic optimization algorithms for the same test system, under the same control variables and system constraints. Simulation results confirm that the hybrid PSO-GWO algorithm performs well compared to other algorithms and shows that it can be an efficient choice for the solution of OPF problems.

Optical injection locking and cavity enhanced four-wave mixing in semiconductor ring lasers have been used to generate data modulated millimeter (mm)-wave optical signals. The scheme is shown to have multigigahertz (multi-GHz) modulation bandwidth. The 4-Gb/s data is transferred directly from an intensity modulated optical signal onto an mm-wave optical signal with the mm-wave frequency tunable in steps of 62.5 GHz and with flexible radio-frequency modulation formats over the optical carrier. Bit-error-rate and eye-diagram measurements confirm excellent signal quality.

Bistability in a semiconductor ring laser with two external optical injections is studied theoretically, numerically, and experimentally. Two optical injections are added to the two counterpropagating modes in the laser respectively. We first predicted theoretically that, with one of them acting as a static holding beam, the intensities of both modes will form a hysteresis loop as a function of the intensity of the second injection due to nonlinear mode competition. The bistability and the hysteresis characteristics such as its width depend heavily on the intensity of the holding beam. Average switching power will increase as the intensity of the holding beam is increased, accompanied by shrinking width of the hysteresis loop. Numerical simulations and experiment are then carried out to verify the theoretical prediction, and the hysteresis loops at different holding beam strength are plotted. The numerical results together with the qualitative experimental results demonstrate what has been predicted by the theoretical analysis, and a good agreement is obtained. The interaction between the two injections demonstrates potentials for application in all-optical digital signal processing.

In this letter we theoretically and numerically investigate the effectiveness of a compact pulse in terms of producing less inter-symbol interference (ISI) and thus less symbol error rate (SER). We present theoretical equations to express the signal to interference plus noise ratio (SINR) for different levels of ISI as well as theoretical SER in terms of quantified compactness of the pulse. In a single compact form equation, we expressed the relationship that connects all the aforementioned terms with each other and with the spectral efficiency. A well-studied ‘better-than-raised cosine’ (BTRC) pulse shape in quadrature amplitude modulation (QAM) is considered and the performance are compared with standard pulses such as Gaussian and raised cosine pulse shapes. Performance comparison results are presented showing that the BTRC pulse outperforms the conventional pulses in both SNIR and SER metrics.

A novel all-optical multicast scheme based on cavity-enhanced four wave mixing in a monolithically integrated semiconductor ring laser (SRL) is proposed. By employing an injecting optical signal resonant with a cavity mode of the SRL, one-to-seven all-optical multicast by means of highly efficient simultaneous multi-wavelength conversion has been experimentally demonstrated up to multi-gigabit data rates. The scheme offers several advantages including low power penalty, reconfigurability, monolithic integration and low cost.