A single mode laser based on coupled cavities of an active ring laser and a Fabry Perot is presented. The laser exhibits tunable single mode behaviour with a side mode suppression ratio of 41 dB and a line-width of 400 kHz.

The trial function approach is a useful technique to modelling soliton solutions for equations that cannot be solved exactly. The authors use the variational approach to find approximate solutions for the dissipative solitons described by the cubic-quintic complex Ginzburg–Landau equation. They find that the evolution equations for the soliton parameters are similar to those derived using the method of moments. The existence of both stationary and pulsating soliton solutions is indicated by both approaches.

The authors investigate the impact of big data's velocity on greening IP over WDM networks. They classify the processing velocity of big data into two modes: expedited-data and relaxed-data modes. Expedited-data demands higher amount of computational resources to reduce the execution time compared with the relaxed-data. They developed a mixed integer linear programming model to progressively process big data at strategic locations, dubbed processing nodes (PNs), built into the network along the path from the source to the destination. The extracted information from the raw traffic is smaller in volume compared with the original traffic each time the data is processed, hence, reducing network power consumption. The results showed that up to 60% network power saving is achieved when nearly 100% of the data required relaxed processing. In contrast, only 15% of network power saving is gained when nearly 100% of the data required expedited processing. The authors obtained around 33% power saving in the mixed modes (i.e. when ∼50% of the data is processed in the relaxed mode and 50% of the data is processed in expedited mode), compared with the classical approach where all the processing is achieved inside the centralised data centres only.

The unified M distribution is recently proposed for analysing turbulence-induced fading effects in wireless optical communication (WOC) systems. In developing this model, the large-scale fluctuations have been approximated by gamma distribution, instead of widely accepted log-normal distribution. However, the accuracy of this approximation decreases when the variance of the log-normal distribution is large. As another approach, the inverse-Gaussian (IG) distribution has been proposed in the literature to model the large-scale fluctuation, results in a new accurate, closed-form distribution termed as S model. To generalise the above results, in this study, the authors propose to approximate the large-scale fluctuations by generalised IG distribution. They show that this new approach results in an accurate, closed-form generalised distribution, called here as H model which includes M and S models as its special cases. To show the applicability of the presented model, they consider a WOC system with heterodyne detection scheme and investigate its bit error rate (BER) performance over H-distributed fading channel. They derive closed-form analytical expression for the BER of the considered system and show that in a special case, it coincides with the results presented in the open technical literature.

Introduction of multiple quantum wells (MQWs) is an efficient way to enhance the light absorption capability in phototransistors. Direct band gap Ge_{1− x} Sn _x alloy (x > 0.08) having large absorption coefficient is an attractive material for heterojunction phototransistors (HPTs) compatible with CMOS platform. In this work, simulations are employed to obtain current gain, responsivity and collector current characteristics of Ge/GeSn/Ge HPTs with incorporation of MQWs (Ge_0.87Sn_0.13/Ge_0.83Sn_0.17) in the base region. The performances of bulk, single quantum well and MQW HPT structures are examined and compared. Best performance is shown by HPTs having MQW structure over a wide range of base emitter voltage.

In this study, the statistical distribution of the received signal in a coherent optical orthogonal frequency-division multiplexing (CO-OFDM) system with quadrature-phase shift keying modulation in the orthogonal frequency-division multiplexing (OFDM) subcarriers is investigated, and the accuracy and correctness of the Gaussian probability density function (pdf) assumption is analysed. The well-known Anderson–Darling test is utilised to measure the deviation extent of the statistical distribution of the received signal from the Gaussian pdf. Finally, the Johnson -distribution is suggested as a more exact distribution for the statistical modelling of the received signal. After non-linear propagation, its accuracy is assessed through comparison with Monte-Carlo simulations, based on the time-domain split-step Fourier method.

A novel coupled electro-optic delayed feedback chaotic system is proposed and studied here. Both electrical coupling and optical coupling are used in this model, where electrical coupling is mainly used to suppress the time-delay signature, and optical coupling is mainly used to improve its complexity. The dynamical performances and complexity are demonstrated, and the simulation results show that the complexity of this model has been greatly improved. Moreover, the time-delay signature cannot be recognised with a low gain, and the suppress effect will be enhanced by increasing the gain coefficient. Comparing with other recently proposed models, the authors model is competitive in security, and has potential applications in secure communication and random number generation.