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Showing papers in "Photonic Network Communications in 2017"


Journal ArticleDOI
TL;DR: The main advantages of the proposed designation can be highlighted as its small sizing as well as simplicity, and the other improvement can be regarded as providing proper distinct space in output between “0” and “1” as logical states.
Abstract: The present study was designed and simulated for an all optical half-adder, based on 2D photonic crystals. The proposed structure in this work contains a hexagonal lattice. The main advantages of the proposed designation can be highlighted as its small sizing as well as simplicity. Furthermore, the other improvement of this half-adder can be regarded as providing proper distinct space in output between "0" and "1" as logical states. This improvement reduces the error in the identification of logical states (i.e., 0 and 1) at output. Because of the high photonic band gap for transverse electric (TE) polarization, the TE mode calculations are done to analyze the defected lines of light. The logical values of "0" and "1" were defined according to the amount of electrical field.

117 citations


Journal ArticleDOI
TL;DR: Simulation results indicate that optical power required to switch the state of PCRR from turn-on to turn-off, for the nonlinearity applied to inner PCRR, is at least 2000mW/μm2 and, for a tunable full-optical add–drop filter, at least 3,000mW-2, which corresponds to refractive index change.
Abstract: In this paper, we investigate the application of Kerr-like nonlinear photonic crystal (PhC) ring resonator (PCRR) for realizing a tunable full-optical add–drop filter. We used silicon (Si) nano-crystal as the nonlinear material in pillar-based square lattice of a 2DPhC. The nonlinear section of PCRR is studied under three different scenarios: (1) first only the inner rods of PCRR are made of nonlinear materials, (2) only outer rods of PCRR have nonlinear response, and (3) both of inner and outer rods are made of nonlinear material. The simulation results indicate that optical power required to switch the state of PCRR from turn-on to turn-off, for the nonlinearity applied to inner PCRR, is at least $$2000\, \hbox {mW}{/}\upmu \hbox {m}^{2}$$ and, for the nonlinearity applied to outer PCRR, is at least $$3000\, \hbox {mW}{/}\upmu \hbox {m}^{2}$$ which corresponds to refractive index change of $$\Delta n_\mathrm{NL }= 0.085$$ and $$\Delta n_\mathrm{NL }= 0.15$$ , respectively. For nonlinear tuning of add–drop filter, the minimum power required to 1 nm redshift the center operating wavelength $$(\lambda _{0} = 1550\, \hbox {nm})$$ for the inner PCRR scenario is $$125\, \hbox {mW}{/}\upmu \hbox {m}^{2}$$ (refractive index change of $$\Delta n_\mathrm{NL}= 0.005)$$ . Maximum allowed refractive index change for inner and outer scenarios before switch goes to saturation is $$\Delta n_\mathrm{NL }= 0.04$$ (maximum tune-ability 8 nm) and $$\Delta n_\mathrm{NL }= 0.012$$ (maximum tune-ability of 24 nm), respectively. Performance of add–drop filter is replicated by means of finite-difference time-domain method, and simulations displayed an ultra-compact size device with ultra-fast tune-ability speed.

65 citations


Journal ArticleDOI
TL;DR: The proposed eight-channel wavelength-division demultiplexer (WDDM) is proposed and designed using two-dimensional photonic crystal (2DPC) ring resonator whose corresponding functional parameters such as transmission efficiency, resonant wavelength, Q factor are investigated.
Abstract: In this paper, eight-channel wavelength-division demultiplexer (WDDM) is proposed and designed using two-dimensional photonic crystal (2DPC) ring resonator whose corresponding functional parameters such as transmission efficiency, resonant wavelength, Q factor are investigated. The proposed structure consists of bus waveguide, dropping waveguide and square ring resonators. Eight different channels are dropped by altering the cavity size and radius of the defect rods. The plane-wave expansion (PWE) and finite-difference time-domain (FDTD) methods are employed to analyse the photonic band gap (PBG) of periodic and non-periodic structure and to arrive normalized transmission spectra, respectively. The resonant wavelengths of eight-channel demultiplexers are 1496.9, 1502.3, 1506.9, 1512.3, 1515.0, 1520.4, 1525.3 and 1530.6 nm. The average transmission efficiency, Q factor and spectral width of proposed demultiplexer are 81%, 825 and 1.8 nm, respectively. The mean channel spacing is about 4.2 nm. The size of the demultiplexer is small; hence, it can be utilized for photonic integrated circuits (PIC).

51 citations


Journal ArticleDOI
TL;DR: This paper has proposed a novel structure for photonic crystal ring resonator with octagon-shaped core that is very sensitive upon the variation of refractive index of total structure and core part of the resonator.
Abstract: Quality factor and refractive sensitivity are significant parameters in designing optical devices such as filters, demultiplexers, switches and sensors. In this paper, we proposed a novel structure for photonic crystal ring resonator with octagon-shaped core. The transmission efficiency of the proposed ring resonator at $$\lambda =1551\,\hbox {nm}$$ is about 99.6 % with bandwidth and quality factor values equal to 0.3 nm and 5170. The proposed structure is very sensitive upon the variation of refractive index of total structure and core part of the resonator, such that the refractive index sensitivity to the refractive index of total structure and the resonant ring core is $$\Delta \lambda /\Delta \lambda =3.1\,\hbox {nm}\,/\,0.01$$ and $$\Delta \lambda /\Delta \hbox {n}=2.9\,\hbox {nm}\,/\,0.01$$ , respectively.

49 citations


Journal ArticleDOI
TL;DR: A MMI-based photonic crystal all-optical logic gate structure for logic functions such as XNOR, XOR, OR and NAND with square-type lattice of Si rods in air host to produce intensity-based logic outputs with high contrast ratio.
Abstract: We present a MMI-based photonic crystal all-optical logic gate structure for logic functions such as XNOR, XOR, OR and NAND with square-type lattice of Si rods in air host. Phase-based logic inputs produce intensity-based logic outputs with high contrast ratio. The calculated ON to OFF contrast ratio for the logic functions XNOR/XOR and OR/NAND is 40.41 and 37.40 dB, respectively. Further, it is improved by 11.53 and 12.46% for XNOR/XOR and OR/NAND logic functions, respectively, by reducing the back reflection with the introduction of absorbing waveguides. The structure in both the forms has a fast response period that is less than or equal to 0.131 ps. The size of the structure is quite compact with dimension $$6.4\,\upmu \hbox {m} \times 8.8\,\upmu \hbox {m}$$ .

48 citations


Journal ArticleDOI
TL;DR: The compact size of the proposed structure and the materials used make the proposed demultiplexer suitable for optical integrated circuits and the use of the device for optical communication applications.
Abstract: In this paper, we employed multilayer ring resonators in a silicon rod base structure to realize 6-channel and 8-channel demultiplexers based on two-dimensional photonic crystals. Both the main rings and basic structures are composed of silicon rods, and the interior rings of the multilayer rings are composed of carbon. Employing silicon and carbon rods of different radii in multilayer ring resonators enhanced the coupling efficiency between the rings and waveguides. The average quality factor and power transmission efficiency were 4320 and 93%, respectively. Crosstalk values from $$-11$$ to −46 dB in conjunction with the mentioned characteristics suggest the use of the device for optical communication applications. The compact size of the proposed structure and the materials used make the proposed demultiplexer suitable for optical integrated circuits.

42 citations


Journal ArticleDOI
TL;DR: This work compares power efficiency of various MLR and single-line-rate (SLR) solutions, and investigates the trade-off that exists between spectral and power efficiency in a WDM network, finding that focusing on spectral efficiency alone results in extra power consumption.
Abstract: In order to tackle the increasing heterogeneous global Internet traffic, mixed-line-rate (MLR) optical wavelength division multiplexed (WDM) networks have emerged as the cost- and power-efficient solution. In MLR WDM networks, channels are structured as sub-bands, each of which consists of wavelengths operating at a similar data rate. By reducing the (1) spacing within a sub-band, or (2) spacing between sub-bands operating at different data rates, spectral efficiency can be improved. However, owing to high physical layer impairment levels, decrease in sub-band spacing adversely affects transmission reach of the channels, which results in higher power consumption due to requirement of increased signal regeneration. In this work, we compare power efficiency of various MLR and single-line-rate (SLR) solutions, and also investigate the trade-off that exists between spectral and power efficiency in a WDM network. Simulation results indicate that (1) for high transmission capacities, a combination of 100 Gbps transponders and 40 Gbps regenerators will obtain the highest power efficiency; (2) for long connection distances, a point ofmerging occurs for various SLR and MLR designs, where power consumption is independent of the frequency band distribution; and (3) for MLR systems, both spectral and power efficiency can be improved by using either shorter links with higher bandwidth assignment to 100 Gbps wavelengths, or longer links with higher bandwidth assignment to 40 Gbps wavelengths. Finally, the results indicate that focusing on spectral efficiency alone results in extra power consumption, since high quality of transmission and spectral efficiency leads to increased regeneration.

40 citations


Journal ArticleDOI
TL;DR: All-optical N-bit digital-to-analog converter based on silicon microring resonators (MRRs) and 1×2 optical splitters, which can convert N- bit optical digital signal to an optical analog signal, is proposed and described in this paper.
Abstract: All-optical N-bit digital-to-analog converter based on silicon microring resonators (MRRs) and $$1\times 2$$ optical splitters, which can convert N-bit optical digital signal to an optical analog signal, is proposed and described in this paper. We design and simulate 2-bit digital-to-analog converter based on two MRRs and two $$1\times 2$$ optical splitters. Two optical pump signals represent the two operands of the logical operations to modulate the two MRRs. The proposed silicon MRRs has high extinction ratios of 16.94 and 15.98 dB at very low pump powers of 1.76 and 1.82 mW, respectively.

29 citations


Journal ArticleDOI
TL;DR: The bee colony optimization (BCO) metaheuristic approach is applied to solve the RSA problem in EON with static traffic demands and results demonstrate that considerable spectrum savings could be achieved with the BCO–RSA algorithm compared to other considered approaches.
Abstract: Elastic optical network (EON) technology is considered as a very promising candidate for future high-speed networks due to its intrinsic flexibility and high efficiency in allocating the optical spectrum resources. The key issue that has to be addressed in EON is the routing and spectrum allocation (RSA) problem. RSA is NP-hard problem that has to be solved in an efficient manner. It is a highly challenging task particularly in the case of large problem instances. In this paper, we applied the bee colony optimization (BCO) metaheuristic approach to solve the RSA problem in EON with static traffic demands. The objective of the proposed BCO---RSA algorithm is to minimize both the network spectrum utilization and the average path length criterions. The results of numerous experimental studies show that our BCO---RSA algorithm performs superior compared to some benchmark greedy heuristics as well as to differential evolution (DE) metaheuristic algorithm recently proposed in the literature. The algorithm is evaluated in different realistic size optical networks, such as the NSFnet, two European optical networks (EON-19 and EON-28) and the USA network topology. Simulation results demonstrate that considerable spectrum savings could be achieved with our BCO---RSA algorithm compared to other considered approaches. In addition, we analyzed the efficiency of the BCO---RSA algorithm and compare it with the competitive DE approach according to the required CPU time and the convergence speed.

27 citations


Journal ArticleDOI
TL;DR: Ring resonator-based channel drop filters are investigated conceptually and analytically with different ring (square and hexagonal) structures and the resonance of circular pillar falls over the region of the third window at C-band which has the lowest attenuation losses and most widely used.
Abstract: Ring resonator-based channel drop filters are investigated conceptually and analytically with different ring (square and hexagonal) structures. In the proposed architecture, silicon rods ($$n=3.4641$$n=3.4641) are contrived over an air substrate of refractive index $$n=1$$n=1 in the equilateral triangular lattice which has the lattice constant $$a=900\,\hbox {nm}$$a=900nm. The characteristics of the design are examined for various types of pillars (circular and elliptical) and are reported in the analysis. The band gap for each structure is calculated and observed by plane-wave expansion method. The normalized transmission spectra and resonance wavelengths for different photonic crystal ring resonators are obtained using 2D finite-difference time-domain method. From the investigation, the resonance of circular pillar falls over the region of the third window at C-band (1530---1565 nm) which has the lowest attenuation losses and most widely used. Full width at half maximum and quality factor of the desired layout are also being calculated. The size of the device is about $$20 \times 14\,{\upmu }\hbox {m}$$20×14μm which is highly compact and useful for the integration of photonic circuits.

27 citations


Journal ArticleDOI
TL;DR: Performance evaluation reveals that the proposed VLC-based model for smart homes is efficient with superior BER performance in a typical smart home environment except for the far corners.
Abstract: Driven by increase in automation, smart homes play an important role in today's human life. This paper presents a new model for smart home technologies based on multi-device bidirectional visible light communication (VLC). For multiple devices and users, orthogonal code-based wavelength division (color beams) full-duplexed bidirectional VLC link is proposed. The color beams from RGB LEDs are utilized to transmit data and synchronize multi-device transmission. To enhance the performance of the proposed model, receiver diversity is also employed. Performance evaluation reveals that the proposed VLC-based model for smart homes is efficient with superior BER performance in a typical smart home environment except for the far corners. The maximum achievable data rate for each user up to four users is found to be 24 Mbps at both uplink and downlink transmissions.

Journal ArticleDOI
TL;DR: Two novel SAC-OCDMA codes are compared in terms of their performances such as bit error rate, number of active users that is accommodated with minimum cross-correlation property, high data rate that is achievable and the minimum power that the OCDMA system supports to achieve a minimum BER value.
Abstract: The optical code division multiple access (OCDMA), the most advanced multiple access technology in optical communication has become significant and gaining popularity because of its asynchronous access capability, faster speed, efficiency, security and unlimited bandwidth. Many codes are developed in spectral amplitude coding optical code division multiple access (SAC-OCDMA) with zero or minimum cross-correlation properties to reduce the multiple access interference (MAI) and Phase Induced Intensity Noise (PIIN). This paper compares two novel SAC-OCDMA codes in terms of their performances such as bit error rate (BER), number of active users that is accommodated with minimum cross-correlation property, high data rate that is achievable and the minimum power that the OCDMA system supports to achieve a minimum BER value. One of the proposed novel codes referred in this work as modified random diagonal code (MRDC) possesses cross-correlation between zero to one and the second novel code referred in this work as modified new zero cross-correlation code (MNZCC) possesses cross-correlation zero to further minimize the multiple access interference, which are found to be more scalable compared to the other existing SAC-OCDMA codes. In this work, the proposed MRDC and MNZCC codes are implemented in an optical system using the optisystem version-12 software for the SAC-OCDMA scheme. Simulation results depict that the OCDMA system based on the proposed novel MNZCC code exhibits better performance compared to the MRDC code and former existing SAC-OCDMA codes. The proposed MNZCC code accommodates maximum number of simultaneous users with higher data rate transmission, lower BER and longer traveling distance without any signal quality degradation as compared to the former existing SAC-OCDMA codes.

Journal ArticleDOI
TL;DR: Simultaneous ultra-compact optical triplexer designed that offers strong transverse confinement of light and is promising candidates for photonic integrated circuits such as wavelength division multiplexing, optical communication and compatible with complementary metal–oxide–semiconductor-Si fabrication processes is reported.
Abstract: Here we reported capable ultra-compact optical triplexer on silicon-on-insulator substrate with resonance cavity for an application of optical communication network Three cavities are used which can separate three communication wavelengths 131, 1445 and 155 $$\upmu $$ m The average output efficiency and quality factor of proposed structure 98% and 2335 obtained, respectively Proposed triplexer has the very low cross talk of −25 to −50 dB Total foot print of structure 284 $$\upmu \mathrm{m}^{2}$$ designed that offers strong transverse confinement of light and is promising candidates for photonic integrated circuits such as wavelength division multiplexing, optical communication and compatible with complementary metal–oxide–semiconductor-Si fabrication processes

Journal ArticleDOI
TL;DR: The performance analysis of relay selection in decode-and-forward (DF)-based mixed radio frequency/free-space optical (RF/FSO) system is carried out and novel analytical expressions for cumulative density function and the moment generating function of the equivalent end- to-end signal-to-noise ratio are derived.
Abstract: In this paper, we carry out the performance analysis of relay selection in decode-and-forward (DF)-based mixed radio frequency/free-space optical (RF/FSO) system. We consider two relay selection schemes, namely max-select and distributed switch and stay, and compare their performance with the system having all relays active. The selected DF relay decodes the received RF signal from source and converts it into an optical signal using the subcarrier intensity modulation scheme for transmission over FSO links. The RF links follow generalized $$\eta -\mu $$?-μ distribution, while the FSO links are subjected to pointing errors and are assumed to follow gamma---gamma distribution. Novel analytical expressions for cumulative density function and the moment generating function of the equivalent end-to-end signal-to-noise ratio are derived. Capitalizing on the derived statistics, we provide the new closed-form expressions of the outage probability for different relay selection schemes.

Journal ArticleDOI
TL;DR: Comparisons among these approaches for the adaptive control of the operating point of a cascade of erbium-doped fiber amplifiers (EDFAs) show that the three proposals outperformed the previous ones in terms of noise figure, gain ripple and BER.
Abstract: In this work we present and analyze three approaches for the adaptive control of the operating point of a cascade of erbium-doped fiber amplifiers (EDFAs), aimed at optical networks performance enhancement. The first approach is called Annealing Search Heuristic with Backpropagation and flexible output (AsHB flex) and uses machine learning concepts to update the amplifier gains through an iterative process. The second one (Exhaustive Method) uses an exhaustive search to evaluate all possible solutions for the problem and obtain the optimum solution. The last one (MaxGain) is a heuristic method that uses previous knowledge about the problem to obtain the solutions. The amplifier characteristics and specifications were obtained experimentally through measurements of gain, noise figure, gain ripple and power consumption on commercially available EDFAs. We performed comparisons among these approaches and others found in the literature, and the results show that the three proposals outperformed the previous ones in terms of noise figure, gain ripple and BER. For example, in a link with four amplifiers the Exhaustive Method achieved a reduction in the cascade noise figure from 10.05 to 5.18 dB, a reduction in the gain ripple from 24.08 to 18.56 dB and a reduction in the BER in almost two orders of magnitude, when compared with the traditional approach, which defines the gain to compensate the loss of the previous link. However, the computation time of Exhaustive Method becomes prohibitive as the number of amplifiers in the link increases. Both MaxGain and AsHBflex obtained similar solutions, close to the optimum operation point in a reasonable time.

Journal ArticleDOI
TL;DR: A new routing algorithm in which turning models, circuit-switching method, different traffic patterns such as Random, Paratec, Madbench, Bitreverse, Cactus, and Tornado are used to reduce optical loss to photonic layer is proposed.
Abstract: Photonic Network-on-Chips is a new generation of Network-on-Chips and has been proposed as a novel solution for the communication infrastructure of chip multiprocessors as well as a different solution to eliminate limitations of Network-on-Chips. Photonic Network-on-Chips has important properties such as increasing communication bandwidth, lowering transmission latency, and lowering power consumption. These networks have some challenges such as routing for transfering photonic data over photonic layer. In this paper, we propose a new routing algorithm in which we use turning models, circuit-switching method, different traffic patterns such as Random, Paratec, Madbench, Bitreverse, Cactus, and Tornado to reduce optical loss to photonic layer. To do this, we have also considered non-blocking five-port router and 2-D Mesh topology. The new proposed routing algorithm can choose different source and destination nodes through selecting the path with the lowest optical loss. So to evaluate optical loss in different paths, we have considered best-case loss path, average-case, and worst-case. This was because we can use best-case loss path in order to transfer photonic data over photonic layer. In the end, proposed routing algorithm with turning models and different traffic patterns shows some improvements of optical loss in photonic layer and notably reduce this factor compared to the other XY dimension-order routing algorithm with 5 ports router.

Journal ArticleDOI
TL;DR: Three- and four-port circulators based on resonators in 2D photonic crystals with square unit cell possessing a low symmetry are investigated and the calculated frequency responses of two circulators are presented.
Abstract: Three- and four-port circulators based on resonators in 2D photonic crystals with square unit cell possessing a low symmetry are investigated. The three-ports are described by only one specific element named antiplane of symmetry. On the other hand, the four-port circulators formed by cascading these two three-ports can have one of the two symmetries. One of them is described by the antiplane of symmetry, and the other symmetry corresponds to a twofold rotational axis. The theoretical part of our paper concerns scattering matrix analysis of the devices with different symmetries and also the operation of the four-port circulator as a single-pole triple-throw switch. Finally, the calculated frequency responses of two circulators are presented.

Journal ArticleDOI
TL;DR: For improving the resource efficiency of dynamic shared path protection in elastic optical networks, a survivable RSA (SRSA)-based heuristic algorithm is proposed in the paper.
Abstract: For improving the resource efficiency of dynamic shared path protection in elastic optical networks, a survivable RSA (SRSA)-based heuristic algorithm is proposed in the paper. In SRSA, an adaptive adjustment link cost function is devised to effectively select working and protection paths. The cost function sufficiently considers available spectrum resources and the length of light paths for both working and protection paths. In order to achieve high resource efficiency, a spectrum allocation strategy named minimal cost stable set is proposed to allocate spectrum for protection paths with respect to the resource efficiency in the link cost function. And the graph coloring algorithm is introduced to select the shared protection path with the highest resource efficiency for the request. Compared with the shared path protection and dynamic load balancing shared path protection, simulation results show that the proposed SRSA decreases bandwidth blocking probability and achieves high resource efficiency.

Journal ArticleDOI
TL;DR: A survey of data center network architectures that use both optical and packet switching components, including electronic processing-based packet switch architectures and hybrid optical–electronic-based switch architectures are presented.
Abstract: This paper presents a survey of data center network architectures that use both optical and packet switching components. Various proposed architectures and their corresponding network operation details are discussed. Electronic processing-based packet switch architectures and hybrid optical---electronic-based switch architectures are presented. These hybrid optical switch architectures use optical switching elements in addition to traditional electronic processing entities. The choice of components used for realizing functionality including the network interfaces, buffers, lookup elements and the switching fabrics have been analyzed. These component choices are summarized for different architectures. A qualitative comparison of the various architectures is also presented.

Journal ArticleDOI
Anwar Alyatama1
TL;DR: An algorithm based on the superposition concept in electrical networks using the Kaufman/Delbrouck recursion model to accurately compute the revenue loss in the OFDM-based single link is developed.
Abstract: Elastic optical networks based on orthogonal frequency-division multiplexing (OFDM) have emerged as the preferred technology for future optical networks because of their good spectral efficiency and flexibility. In OFDM optical networks, multiple subcarriers can be allocated to accommodate both subwavelength and superwavelength traffic. In this work, we developed an algorithm based on the superposition concept in electrical networks using the Kaufman/Delbrouck recursion model to accurately compute the revenue loss in the OFDM-based single link. The algorithm is applicable when there are many call types requesting diverse numbers of contiguous subcarriers offered to a link with numerous subcarriers.

Journal ArticleDOI
TL;DR: An energy efficient adaptive optical code division multiple access (OCDMA) random access protocol based on particle swarm optimization (PSO) is described, based on the S-ALOHA with power and rate allocation based on PSO.
Abstract: In this paper, an energy efficient adaptive optical code division multiple access (OCDMA) random access protocol based on particle swarm optimization (PSO) is described. This protocol is based on the S-ALOHA with power and rate allocation based on PSO. This scheme evaluates jointly optimal power and rate allocation PSO based under the random access protocol as a new and simplified scheme for high performance, high energy efficiency suitable for OCDMA systems. The aim is to maximize the aggregate throughput, subject to predetermined quality of service restrictions and energy efficiency constraint in terms of the signal-to-noise-plus interference ratio of each user class. Numerical results are discussed taking into account realistic network operation scenario.

Journal ArticleDOI
TL;DR: A new QoS provisioning tri-mode energy saving scheme is proposed, by integrating the Doze mode into original dual-mode design, to allow the ONU to switch to one of the energy saving modes whenever no upstream traffic exists.
Abstract: The Ethernet passive optical network provides broadband Internet access but also consumes a lot of energy. Energy saving mechanisms using the dual-mode--Active and Sleep modes--design for optical network unit (ONU) in EPON still suffer unnecessary energy consumption, especially in asymmetric data flow such as video streaming downloading service. The Doze mode is particularly suitable for handling the asymmetric data flow since it allows the ONU's transmitter to turn off while turning on its receiver to receive data from optical line termination (OLT). However, adding Doze mode into original dual-mode design incur a greater challenge for OLT to identify the current status of the ONU since the ONU cannot transmit any upstream message to OLT at either Doze or Sleep mode. In this paper, we propose a new QoS provisioning tri-mode energy saving scheme, by integrating the Doze mode into original dual-mode design, to allow the ONU to switch to one of the energy saving modes whenever no upstream traffic exists. A high-priority upstream packet, arriving at ONU of energy saving modes, is able to trigger the ONU back to Active mode for QoS provisioning purpose. Performance evaluation via simulation has demonstrated the effectiveness of such mechanism in various asymmetric data flow. Furthermore, we propose two additional enhanced approaches to increase the energy saving effects by deferring the triggering action of the high-priority upstream packet as well as coalescing new arrival packets during waiting time into the same scheduling cycle.

Journal ArticleDOI
TL;DR: A novel software-defined clustered-optical access networking (SD-COAN) architecture is proposed for data center services in ubiquitous data center optical interconnection to enhance the responsiveness to the dynamic end-to-end data center demands and globally optimize optical access network and application resources effectively.
Abstract: Ubiquitous data center optical interconnection between user and data center has become a promising scenario gradually to accommodate high-performance services with end-to-end quality guaranteed. In our previous work, we implemented to provision data center application in inter-data center optical interconnection. In view of this, this study extends to consider the networking relationship between user and data center. We propose a novel software-defined clustered-optical access networking (SD-COAN) architecture for data center services in ubiquitous data center optical interconnection. A cross-stratum flow schedule (CSFS) strategy is introduced for SD-COAN based on the proposed architecture. The SD-COAN can enhance the responsiveness to the dynamic end-to-end data center demands and globally optimize optical access network and application resources effectively. The overall feasibility and efficiency of the proposed architecture are experimentally verified on our OpenFlow-based enhanced SDN testbed. The performance of CSFS strategy under heavy traffic load scenario is also quantitatively evaluated based on SD-COAN architecture in terms of resource occupation rate, average throughput and average provisioning delay, compared with other provisioning strategy.

Journal ArticleDOI
TL;DR: It is found that the advantage in reducing the transmission bandwidth of SM cannot compensate its limitation in suffering from geometric spreading, and it is proposed to combine N-SM with pulse-position modulation (L-PPM) and transmit diversity to improve the performance of SM-based FSO systems.
Abstract: A number of studies recently have proposed optical spatial modulation (SM) as a simple, power- and bandwidth efficient modulation scheme for free-space optical communication (FSO) systems. In these studies, it was assumed that an active laser source only sends the signal to one targeted photodetector (PD). However, undesirable PDs still can receive the signal from the active source due to geometric spreading (i.e., laser beam broadening). In addition, if the fading channels between the active source and multiple PDs are correlated, the probability of wrong detection of the active source’s index during spatial demodulation process may increase. In this paper, we first analyze the impact of geometric spreading on the performance of FSO systems using SM over uncorrelated Gamma–Gamma fading channel. We find that the advantage in reducing the transmission bandwidth of SM cannot compensate its limitation in suffering from geometric spreading. We then propose to combine N-SM with pulse-position modulation (L-PPM) and transmit diversity ( $$M\,\times \,1$$ MISO) to improve the performance of SM-based FSO systems. The numerical results, which are validated by Monte–Carlo simulations, confirm the superiority of the proposed system in comparison with the conventional ones.

Journal ArticleDOI
TL;DR: It has been revealed that reduced gain recovery time-optimized SOAs-based all-optical half-subtracter arranged in a co-propagating manner exhibits improved Q-factor and ER (dB) performance at high bit rates of operation.
Abstract: In this article, the acceleration attained in gain recovery dynamics of travelling-wave-type semiconductor optical amplifier (SOA) at the expense of structural optimization is illustrated via numerical simulations. A pump–probe scheme has been utilized in order to study the outcomes of optimization of SOA operational and structural parameters on its effective gain recovery time ( $${\tau _\mathrm{e}}$$ ). A set of optimized SOA parameters are formulated from gain recovery dynamics studies after keeping practical implementation considerations in vision. Further, the impacts of altering SOA structural and operational parameters such as injection current (I), amplifier length (L), active region width (w), active region thickness (t) and optical confinement factor ( $${\varGamma } $$ ) on gain recovery time improvement achieved are further investigated on the performance of a cross-gain modulation (XGM) in SOA-based all-optical half-subtracter in terms of two designated performance metrics: quality factor (Q-factor) and extinction ratio (ER). It has been revealed that reduced gain recovery time-optimized SOAs-based all-optical half-subtracter arranged in a co-propagating manner exhibits improved Q-factor and ER (dB) performance at high bit rates of operation ( $$\le $$ 80 Gbps).

Journal ArticleDOI
TL;DR: A simple wavelength-division-multiplexing passive optical network that can support the virtual-ring local area network (LAN) services transmitted among optical network units in a cost-effective way is proposed.
Abstract: A simple wavelength-division-multiplexing passive optical network is proposed in this paper. By simply designing the remote node, the virtual-ring local area network (LAN) services transmitted among optical network units are realized. And coupled with conventional broadband light source and spectrum-sliced technology, the network can support the LAN services in a cost-effective way. More particularly, the whole wavelength band of downstream services can also be reused for LAN services by selecting a special port of Arrayed Waveguide Grating. The simulation results indicate the 10 Gb/s LAN communication in this network can be achieved with the help of forward error correction.

Journal ArticleDOI
TL;DR: A QoS-aware energy-saving mechanism designed to reduce the delay and congestion caused by ONUs’ sleep, and which can effectively improve the energy efficiency and meet the QoS requirements of packets is proposed.
Abstract: Hybrid optical-wireless broadband access network (HOWBAN) takes full advantage of the high capacity and reliability of the passive optical network and the flexibility, ubiquity of the wireless network. Similar to other access networks, the issue of high energy consumption is a great challenge for HOWBAN. In HOWBAN, optical network units (ONUs) consume a great amount of energy. The sleep of ONUs can greatly improve the energy efficiency of HOWBAN. However, the quality of service (QoS) will be decreased while the packets are waiting in ONUs and optical line terminal. In this paper, we propose a QoS-aware energy-saving mechanism. A dynamic bandwidth allocation mechanism is designed to guarantee the QoS, where different priorities are considered. Meanwhile, we employ different sleep strategies by taking different priorities’ tolerant delays into account to prolong the sleep time of ONUs. Then, based on the evaluation of packet delay, the optimal sleep parameter is derived to maximum the energy efficiency. In addition, a load balancing and resource allocation mechanism is adopted in the wireless domain to reduce the delay and congestion caused by ONUs’ sleep. Results show that the proposed mechanism can effectively improve the energy efficiency and meet the QoS requirements of packets.

Journal ArticleDOI
TL;DR: The considered Routing, Modulation Level and Spectrum Allocation problem covers path length minimization while still meeting the spectrum continuity constraints, non-overlapping spectra constraints, spectrum contiguity constraints, and choice of modulation level.
Abstract: The considered Routing, Modulation Level and Spectrum Allocation (RMLSA) problem covers path length minimization while still meeting the spectrum continuity constraints, non-overlapping spectra constraints, spectrum contiguity constraints, and choice of modulation level. In this problem, the relationship between spectrum connection and bit rate of the incoming request has been taken into account. In this paper, two algorithms have been proposed. The first one is based on a set of shortest paths whose lengths are determined by the number of links in the network. The second one is a modified version of Dijkstra’s algorithm. Modification of this algorithm is based on introduction of weights of the network links depending on the utilization of the links and the introduction of a aggregated spectrum of the path that is being selected. Extensive research has shown that algorithms reject the lower traffic volume as compared to well-known algorithms proposed in literature.

Journal ArticleDOI
TL;DR: The characteristics of the simulator, its architecture and considered parameters, along with some examples of the simulations that can be executed on it are presented and an developed simulation tool called Simulator for Elastic Optical Networks (SimEON) is presented.
Abstract: In comparison with wavelength division multiplexing optical networks, elastic optical networks are much more flexible, presenting an efficient alternative to use the frequency spectrum to establish call requests in a scenario with different transmission bit rates and modulation schemes. Due to the variety of optical devices, node architectures and physical topologies, it is difficult to implement optical network prototypes to analyze operational scenarios in terms of blocking probability of call requests, the impact of capital and operational expenditures and energy consumption, for example. To our knowledge, there is no available open-source simulation tool exclusively for elastic optical networks in the literature. There are a few simulation tools that were used to obtain results for optical networks but most of their source codes are unavailable. The state of the art of these simulators and our developed simulation tool called Simulator for Elastic Optical Networks (SimEON) are presented. SimEON is an open-source software. It is developed under the GNU Lesser General Public License and takes into account principles of software engineering. In this article, we present the characteristics of our simulator, its architecture and considered parameters, along with some examples of the simulations that can be executed on it.

Journal ArticleDOI
TL;DR: It is shown that it is possible to expand the optical network with limited available channel bandwidth by utilizing the wavelength converter and gives an approach to implement wavelength converter for future hybrid optical access networks.
Abstract: In this paper, the design and analysis of the all-optical up- and down-wavelength converter based on four-wave mixing (FWM) effect of semiconductor optical amplifier Mach–Zehnder interferometer (SOA-MZI) have been presented. The return-to-zero (RZ) modulated data signal at a bit rate of 60 Gbps has been evaluated for error-free operation to show the feasibility of proposed system at different pump wavelength. The converted signal power and quality factor are investigated as the function of variable signal power and pump power. The optimized operating input signal power of −5 dBm with Q-factor of $$\sim $$ 28 dB for RZ modulated signal by using SOA-MZI structure with enhanced FWM effect. The important contribution of these investigations that it is possible to expand the optical network with limited available channel bandwidth by utilizing the wavelength converter and gives an approach to implement wavelength converter for future hybrid optical access networks.