Analytical study of nonlinear phase shift through stimulated Brillouin scattering in single mode fiber with the pump power recycling technique.

We present a theoretical study of nonlinear phase shift through stimulated Brillouin scattering in single mode optical fiber. Analytical expressions describing the nonlinear phase shift for the pump and Stokes waves in the pump power recycling technique have been derived. The dependence of the nonlinear phase shift on the optical fiber length, the reflectivity of the optical mirror and the frequency detuning coefficient have been analyzed for different input pump power values. We found that with the recycling pump technique, the nonlinear phase shift due to stimulated Brillouin scattering reduced to less than 0.1 rad for 5km optical fiber length and 0.65 reflectivity of the optical mirror, respectively, at an input pump power equal to 30mW

Analytical analysis of second-order Stokes wave in Brillouin ring fiber laser.

This paper details a theoretical modeling of Brillouin ring fiber laser which incorporates the interaction between multiple Brillouin Stokes signals. The ring cavity was pumped at several Brillouin pump (BP) powers and the output was measured through an optical coupler with various coupling ratios. The first-order Brillouin Stokes signal was saturated with the presence of the second-order Stokes signal in the cavity as a result of energy transfer between them. The outcome of the study found that the optimum point for the first-order Stokes wave performance is at laser power reduction of 10%. Resultantly, at the optimum output coupling ratio of 90%, the BFL was able to produce 19.2 mW output power at BP power and Brillouin threshold power of 60 and 21.3 mW respectively. The findings also exhibited the feasibility of the theoretical models application to ringtype Brillouin fiber laser of various design parameters

An optimal algorithm for better efficiency in WMSN for multimedia applications

Abstract The recent trends in wireless network sensor technology are moving towards multimedia applications. Multimedia sensor nodes are difficult to communicate, but communication is necessary. Multimedia service offers both video monitoring and voice over wireless sensor networks. This causes severe problems with usage of data, power, bandwidth, energy usage and wireless sensor network deployment costs. The key restriction for the expansion of a network is the energy conservation. The nodes are distributed in the field to collect audio, video and density information so as to collect the information from sensors. The network of wireless sensors provides different layer nodes depending on their power level. In this work, Enhanced Greedy Forwarding with efficient Multi‐path and Dynamic Routing (EGFMDR) protocol was proposed and the results were compared with existing state‐of‐the‐art protocols like Ad‐hoc On‐demand Distance Vector and DYMO. Depending on how powerful they are, multi‐stage architectures were employed in various areas such as observation, military, media and traffic surveillance. They retain the effectiveness of wireless sensor network in multimedia applications. Service quality protocol parameters were analysed, and from the simulation results attained, the proposed EGFMDR protocol displays reduced end‐to‐end delay, lesser packet loss ratio and increased energy efficiency

Analytical modeling, experimental investigation and applications of stimulated Brillouin scattering in optical fibers

In the work presented in this dissertation, the generation of stimulated Brillouin scattering (SBS) and its applications in optical fibres are theoretically and experimentally investigated. The initial work is concerned with the investigation of SBS threshold power reduction techniques. The method under study is namely a pump recycling technique in which the residual pump power is recycled back to act as the secondary pump. A new mathematical model was developed for the proposed technique. The results obtained from this model compare favorably with the experimental results. The pump recycling technique can reduce the SBS threshold by around 50% as compared to the one obtained from the conventional technique. The threshold exponential gain of SBS is very critical in determining the performance of the Stokes signal. Particle swarm optimization (PSO) is utilized to optimize this parameter. The simulation results obtained from the PSO model are compared with two other established models: the localized, non-fluctuating source model and the distributed (non-localized) fluctuating source model. For the PSO model, the threshold exponential gain increases from 15.9 to 17.4 from 5 to 1 km respectively. The threshold exponential gain for long fibers (L > 5 km) is gradually decreased and close to 14.6. Theoretical models of the Brillouin fiber laser in a ring cavity were also developed. Even though the Stokes laser is designed to propagate unidirectionally along the optical fibre, the second-order Stokes signal can also be produced when the SBS threshold condition is satisfied. Even though this second-order Stokes signal cannot make a complete round trip because of the isolation provided by the circulator, it affects the amplification of the first-order Stokes signal. This influence has been considered in the development of the theoretical model. An optimum operating point is determined in order to obtain an acceptable output power with only 10% of the power transferred from the first-order Stokes signal to the second-order Stokes signal.A theoretical model of a double-Brillouin-frequency shifter (DBFS) is demonstrated to achieve a double-spacing Stokes signal. Evidence of the higher-order Stokes signal generation becomes the foundation of the theoretical model development of DBFS. For the proposed structure, the 4-port circulator is used to isolate the propagation of odd- and even-order Stokes signal in a ring cavity structure. Although the proposed double- Brillouin-frequency shifter is able to generate the second-order Stokes signal, it also suffers from producing higher-order Stokes waves. Therefore, the developed theoretical model includes the Stokes wave interaction up to its fourth order. The analysis of sidemode suppression ratio can be achieved because the proposed DBFS allows the propagation of the remaining Brillouin pump and higher even-order Stokes signal. There is an optimum Brillouin pump power to achieve a maximum side-mode suppression ratio

Brillouin linewidth characterization in single mode large effective area fiber through co-pumped technique

Brillouin linewidth has been studied experimentally for single mode large effective area fiber using the co-pumped technique. The Brillouin linewidth with different fiber lengths and it relationship with stimulated Brillouin scattering threshold power are given. Our experimental results indicates that threshold power of stimulated Brillouin scattering reduction by 23.018% using the dual-end-pumped technique to the co-pumped technique measured for -7 dBm. This ratio at threshold depends on both Brillouin pump and probe signal powers. Evolution from the non-stimulated to stimulated scattering regions is examined by calculating the linewidth of the Brillouin gain spectrum. It is shown that linewidth undergoes Brillouin gain spectrum narrowing as the Brillouin pump power is increased and probe signal power is decreased. The results highlight the narrowest Brillouin linewidth of the Stokes wave range lies between 9 MHz and 14 MHZ for input probe signal power -7 dBm and 14 dBm laser pump power with different fiber lengths

Effects of pump recycling technique on stimulated Brillouin scattering threshold: a theoretical model

We develop a theoretical model that can be used to predict stimulated Brillouin scattering (SBS) threshold in optical fibers that arises through the effect of Brillouin pump recycling technique. Obtained simulation results from our model are in close agreement with our experimental results. The developed model utilizes single mode optical fiber of different lengths as the Brillouin gain media. For 5-km long single mode fiber, the calculated threshold power for SBS is about 16 mW for conventional technique. This value is reduced to about 8 mW when the residual Brillouin pump is recycled at the end of the fiber. The decrement of SBS threshold is due to longer interaction lengths between Brillouin pump and Stokes wave

A Provably Secure Anonymous Authentication Protocol for Consumer and Service Provider Information Transmissions in Smart Grids

Smart grids integrate information technology, decision support systems, communication networks, and sensing technologies. All these components cooperate to facilitate dynamic power adjustments based on received client consumption reports. Although this brings forth energy efficiency, the transmission of sensitive data over the public internet exposes these networks to numerous attacks. To this end, numerous security solutions have been presented recently. Most of these techniques deploy conventional cryptographic systems such as public key infrastructure, blockchains, and physically unclonable functions that have either performance or security issues. In this paper, a fairly efficient authentication scheme is developed and analyzed. Its formal security analysis is carried out using the Burrows–Abadi–Needham (BAN) logic, which shows that the session key negotiated is provably secure. We also execute a semantic security analysis of this protocol to demonstrate that it can resist typical smart grid attacks such as privileged insider, guessing, eavesdropping, and ephemeral secret leakages. Moreover, it has the lowest amount of computation costs and relatively lower communication overheads as well as storage costs