OBS JET was defined as a one-way reservation scheme without any acknowledgement o f successful (or unsuccessful) burst transmission [QiaOO/1]. A two-way reservation scheme has also been proposed (no. 7, [W ei99]), but there it was assumed that bursts are also sent prior to the receipt o f an acknowledgement, so at the time o f sending it is unclear whether the burst w ill arrive at its destination. This scheme, termed ‘Just-in- Time (JIT)’ is explained along with OBS JET in more detail in section 126.96.36.199. Recognizing this as a limitation, schemes [Dol02, QiaOO/2, YooOO] have been proposed to provide class-of-service differentiation by offset times, i.e. to assign larger offsets for higher priority traffic. This, however would have the effect o f reducing the burst loss for high priority traffic, at the expense o f an increase for lower priority bursts, especially for dynamically varying traffic loads. The result is reduced network capacity for acceptable burst loss rates [DolOl/1], jeopardizing the initial rationale o f OBS to increase utilization o f resources. In OBS networks with one-way reservation, lower priority bursts experience loss as a penalty. However, given that each burst may contain a large number o f TCP/IP (transmission control protocol, internet protocol, [Kes97]) acknowledgements representing up to 50% o f traffic [XioOO], each lost burst would affect a number o f higher layer connections. So in OBS networks care should be taken to also minimize the loss o f lower priority bursts to prevent this. Keeping to predefined latencies is also essential since some protocols such as TCP/IP operate with timeouts and trigger re-sending o f packets after a pre-set time-out, even if packets were not lost but held up in a queue within the network. Even deflection routing (see for instance [MyeOl]) would bring little benefit since out-of-order burst arrivals w ill require large buffers in the receiving edge routers for re-ordering. Although buffers for higher layer protocols such as TCP are designed to hold (and re-order) traffic for a full network round-trip time, burst loss would aggravate the problem o f re-ordering since a number o f TCP sources would potentially re-start transmission, requiring larger buffer sizes than already used. Finally, in all the proposed schemes, wavelengths are assigned on a link- by-link basis, requiring full wavelength conversion at every node, as end-to-end lightpath reservation is difficult because o f short offset times and short packets. Hence wavelengths are not used for routing, as in WRONs (section 1.2.1), but simply to increase available transport channel capacity.
To achieve maximum redundancy and protection in the system, all the SFMs in the OTN switch should be able to share the traffic load. As well as achieving effective load balancing, this architecture ensures that, should one card fail, the remaining cards can redistribute the extra traffic between them to avoid service interruptions. This structure also enables CSPs to carry out upgrades while the OTN switch remains in service. Similarly, redundancy should be provided in the power supply cooling fans and system controllers. Combined with service protection, this results in the highest, carrier-grade, availability. Figure 5 summarizes the switch architecture from the perspective of the signal format. It illustrates ODU switching functionality, which is used for all different formats. Alternative approaches might include packet switching for MPLS/Ethernet signals using an MPLS interface card, or SONET interfaces for ODU or VC4-based switching, all handled by the same switch fabric. Therefore, the OTN switch becomes the only switching element for all the formats present in the network.
With the presence of all-optical networks it is important to realize that upper layers will still be functioning in electronic domain due to presence of electronic devices. Due to very high bandwidth the existing applications and presentation layers might not be able to cope with AONs and changes will be needed to meet the high-speed network demands. In OSI reference model, some of the network functions were duplicated in more than one layer, e.g., error and flow control was implemented at both data link and transport layer. It is targeted that once allopticalnetwork is deployed this complexity can be avoided and clear distinction of responsibilities be made for each layer. Opticalnetwork architecture aims to simplify the structure thus making it efficient enough to utilize the bandwidth of opticalnetwork efficiently. AONs with circuit switched networks bring a higher degree of transparency. Three generations of network architecture are shown in (Figure 29) ,  and .
In SS-FON, three switching paradigms are [8, 15]: (a) independent switching (Ind-Sw) that makes it possible to direct any spatial path independently to any output port; (b) joint switching (J-Sw) that switches all the spatial paths altogether, and (c) fractional joint switching (FrJ-Sw) that switches subgroups of spatial paths as an entity. The performance of different switching paradigms are investigated in regard to the number of needed transponders , required number of SSS , and traffic profile effect [16, 17]. Also, the fragmentation problem has been addressed in [18-20]. Ind-Sw brings out higher network performance for dynamic traffic, but it requires more complex switches. In addition, the used transmission media should have no crosstalk or energy coupling between spatial paths, e.g., use of SMF bundles or weak coupled MCFs. FrJ-Sw performance is between Ind-Sw and J-Sw. On the other hand, the reduction of cost per bit and transceivers number are the important outcomes of J-Sw. Also, it is possible to use all the SDM fibers in J-Sw. Therefore, J-Sw is an interesting solution for migration of an opticaltransportnetwork to a full flexible one. Thus, the network planning of SS-FONs with J-Sw paradigm is investigated in this paper.
Photonic slot routing has been proposed as an approach to implement an all-optical packet-switched network in a manner which is scalable and not overly complex. In photonic slot routing, packets are transmitted within a basic transport unit referred to as a photonic slot. The photonic slot is fixed in length and spans multiple wavelengths. Each photonic slot is routed through the network as a single entity; thus, individual wavelengths do not need to be multiplexed or demultiplexed at intermediate nodes through which the photonic slot is traversing. When implementing photonic slot routing in a mesh environment, a number of significant issues must be addressed. Two such issues are fairness and contention resolution. In this study, we propose a novel approach for allocating capacity on each link in a fair manner, and we investigate various approaches, such as buffering and deflection, for handling contention. We develop an analytical model to evaluate the performance of such networks, and validate the analysis through simulation. It is shown that the proposed capacity allocation approach can significantly reduce contention in the network and provide a fair allocation of bandwidth to each source-destination pair.
For that the device geometry is such that with input optical signals at one facet and output at another with insignificant facet reflections taken as a traveling wave amplifier. For the reflective SOA (RSOA) mode the output and input optical signals utilize the similar facet, and the opposite facet is arranged extremely reflective and parameter power reflectivity is defined. Here the signals experience two passes all the way through the SOA prior to exiting. Here there are two input ports and one output port. Accordingly one or more optical signals are accepted by first input where as second input accepts an elective electrical modulation current. Subsequently, resulting output optical signal is generated by output port. It makes use of cross gain modulation, for the augment in the input power there is depletion of carriers in the gain region of the semiconductor optical amplifier (SOA) as a consequence there is reduction in the gain of amplifier and the gain acts in tune with the variations in input power on a bit-by-bit basis. Low and high gains are experienced for one and zero bit in the input signal respectively when a low-power probe wave at a different wavelength is injected within semiconductor optical amplifier. An optical filter Fabry Perrot is used to eliminate the high-powered signal in order to avoid counter propagation of pump and probe signal. The key simulation parameters are as explored in the table1. For the necessary measurement subsequently output is employed to BER scope and eye pattern measurement.
agreement of simulated and measured MTFs further was resisted. It would be over-optimistic to think that alloptical and x-ray processes were modeled accurately given the unknowns. Firstly, experimental errors and uncertainties are inevitable in the measurement of MTFs e.g. in extrapolation of line-spread-function tails. 18 Secondly, there is uncertainty in the amount, composition and location of scattering material that was above and below the phosphor screens in experimental measurements. 345
The OptiSystem software was developed to equip the academic world with an advance teaching and research product in order to minimize the lecture preparation hour, promoting efficient learning process by providing samples to be simulated during class hour and supporting the researchers to understand the background of the optical device and network by simulating and analyzing their design before building up the real test bed (Carl, 2007). Furthermore, there are numbers of paper reporting on the new achievements and studies using this powerful and user friendly simulation tool (Hamel-Bissell, 2010; Xiang-Yue et al., 2011; Ali et al., 2012; Junita et al., 2012; Khaleel, 2012).
Growing demand for high speed internet is the primary driver for the new access technologies which enable experiencing true broadband. It leads telecommunication operators to seriously consider the high volume roll-out of optical-fiber based access networks. They have to renew their access networks that are clearly becoming the bottleneck in terms of bandwidth. Fiber to the Home FTTH appears the most suitable choice for a long term objective: if the clients are wholly served by optical fibers, it will be easier to increase the bandwidth in the future. FTTH is future proof solution for providing broadband services such as Video on demand, Online Gaming, HD TV and VoIP. Passive opticalnetwork (PON) based FTTH access network is a point-to-multipoint, fiber to the premises network architecture in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises, typically 32–128.Fiber to the Home networks exploit the low attenuation (0.2–0.6 dB/km) and high bandwidth (>30,000 GHz) of single mode optical fibers  to provide many times more bandwidth than currently available with existing broadband technologies. In addition, these networks have the ability to provide all communication services viz. voice, data and video from one network platform. Several Time Division Multiplexing TDM PON technologies are standardized for FTTH deployments, Table 1 summarizes these standards with their important parameters. The main disadvantage of TDM PON is that it not possible for different operators to physically share the same fiber. A multi-fiber deployment is necessary to physically share the access network. Wavelength Division Multiplexing Passive Optical Networks WDM PONs is the next generation in the development of access networks. Two flavors of WDM-PON are being studied by Study Group 15 (SG15) of the International Telecommunication Union Telecom Standardization Sector (ITU–T) . The first one is time and wavelength division multiplexing PON (TWDM PON) which transmits 4-16 wavelengths on the same fiber to support higher number of users per fiber at higher transmission rates or more importantly to allow more than one operator sharing the same fiber, i.e. Operators can work with different wavelengths. The second one is arrayed waveguide grating (AWG)-based
The main objective of new technologies is to provide best services to users with lower cost terms. Main part is to be considering here is for making cost-efficient network with better capacity, speed and in better flexibility manner. Hence for cost-efficient network number of ONU should be placed in optimal way. As we can see that up till now work on ONU placement is done by applying Hybrid and Genetic algorithms is the best solution in terms of deployment reduction in cost but from practical implementation we can see that number of ONU is reducing but number of users were as it is in available network. We cannot predict exact number of users or traffic in a specific region of network. These may causes interference between communications and also weaken the network in terms of efficiency. In that way we can say that method which provides us better results in reduction of ONUs and reducing the interference between users is effective and cost-efficient network. Through extensive simulation, we have determined that our algorithm requires less number of ONUs than in previously discussed algorithms. So we can say that, the HA and GA algorithm is better for deployment of cost-efficient FiWi network.
112 strong-coupling regime via stimulated polariton-polariton scattering 19-21 by an applied probe beam to a final state where light is more photonic in character. Though enhancement from a spectrally well-defined pump resonant with the exciton-polariton bottleneck reservoir is a common focus of stimulated scattering literature, direct observation of initial state depopulation 22 as well as scattering from nonresonant pump excitation into a broad distribution of final state momentums 23 have also been reported. Figure 8.6a shows a nanowire with 40 nm-wide cut, as well as optical images of the upper portion lasing under Ti:Sapphire excitation and the lower portion emitting photoluminescence under focused Ar+ excitation (Ti:Sapphire pumping off). Spectra collected from the bottom end facet are shown for each case in Figure 8.6b and Figure 8.6c, respectively, and the experimental waveguide dispersion for the lower portion as culled from the Fabry-Pérot peaks 4 in Figure 8.6c is plotted alongside the numerically- calculated fundamental mode dispersion. 15 As shown in Figure 8.6c, the addition of the Ar+ laser not only creates additional polaritons at the same momentum as the dominant laser peak at 2.505 eV, but also partially occupies many final states over the momentum range k z = 2.1 x 10 7 to 2.5 x 10 7 m -1 . We believe scattering of the primary laser peak to
While optical technology provides the best solution for the transmission of information, all-optical devices must satisfy several qualitative criteria to be used as logic elements. In particular, cascadability is difficult to obtain in optical systems, and it is assured only if the output of one stage is in the correct form to drive the input of the next stage. Exciton-polaritons, which are composite particles resulting from the strong coupling between excitons and photons, have recently demonstrated huge non-linearities and unique propagation properties. Here we demonstrate that polariton fluids moving in the plane of the microcavity can operate as input and output of an all- optical transistor, obtaining up to 19 times amplification. Polariton propagation in the plane of the microcavity is then used in turn to control the switching of a second, spatially separated transistor, demonstrating the cascadability of the system. Moreover, the operation of the polariton transistor as an AND/OR gate is shown, validating the connectivity of multiple transistors in the microcavity plane and opening the way to the implementation of polariton integrated circuits.
Austria features an excellent network of transport system and transshipment hubs. Inland ports on the Danube with a connection to the North Sea and the Black Sea, railway links to the large Adriatic ports, Vienna as the interface for air freight, especially to South East and Eastern Europe, and the excellent interaction of all these modes of transport provide the ideal pre-requisites for modern business. On balance, Austria has 26 intermodal terminals which ensure the optimal combination of road, rail and waterway traffic. Four further large rail terminals located in Wolfurt, Wörgl, Wels and Vienna will be expanded by 2017 at a cost of EUR 390 million.
In conclusion, we demonstrated an all-optical tunable filter using coupled photonic crystal nanobeam cavities, where a considerable portion of the tuning is affected by mechanical reconfiguration. Specifically, we measured a total tuning of filter resonance of more than 18 linewidths, out of which 20% was due to OM effects. As demonstrated, OM-tuning effects are much faster than the thermal ones in our system, which is important for practical applications. The operating speed of OM devices could be pushed into the giga- hertz regime by using smaller and stiffer structures, at the expense of the increased optical power needed to actuate them. Our scheme allows for a wide range of pump wavelength selection while over- coming the limitation of self-detuning of the pump and can be used to simultaneously control multiple devices. At the same time, independent control over the mechanical response was also achieved by varying the pump laser’s wavelength. Our technique is a promising candidate for realization of reconfigurable and program- mable optical devices, including filters and filter banks, routers and modulators.
the HOT. These controls, named "amplitude" and "offset", changed the gradient and y-intercept of the straight line representing the SLM response. They were altered until the straight line matched the linear regime shown in 4.4. In practice this is accomplished by displaying a blazed grating on the SLM and observing the relative intensities of the zeroth and first diffracted orders. The optimal values of the amplitude and offset are those which maximise the intensity of the first diffracted order. Even once the performance of the SLM has been maximised there will still be losses associated with it . An as example case, consider a SLM displaying a single blazed grating. Because only the first diffracted order is used in HOT, optical power that remains in the zeroth order is effectively lost by the system. Additionally, the structure of the SLM itself leads to further loses. Although SLMs are available which use their whole surface , most do not. Rather, the surface of the SLM is not continuous, but is instead made from a collection of pixels, each padded with a deadzone. As a result, the SLM acts as a 2 − D grating and therefore diffracts light into other orders regardless of what phase pattern is displayed on it.
Photonic membranes (PMs) are thin, highly-flexible, membranes which can be imbued with specific photonic functionalities when used to play host to plasmonic features. 1–3 PMs can then take that photonic functionality and transfer it to an external object, provided that they can be manipulated with enough precision. We demon- strate a fabrication and optical manipulation protocol that allows PMs to be manoeuvred through a microfluidic environment, and show that the trap stiffness of such a scheme is on par with current techniques. The PMs shown here are 90 nm thick, with the potential to be extremely flexible. We comment on their current deformability.
Several recent studies have combined a genetically encoded calcium indicator with an optogenetic probe for all-optical inter- rogation in vivo. Two groups (Rickgauer et al., 2014; Packer et al., 2015) combined two-photon population calcium imaging with two-photon optogenetics to achieve simultaneous readout and manipulation with single-cell and single-action-potential preci- sion in head-fixed awake mice in vivo. Rickgauer et al. (2014) used TF to target manipulation to individual CA1 pyramidal cells, enabling them to bias place cell firing during navigation in virtual reality. In contrast, Packer et al. (2015) used an SLM to target multiple functionally characterized cells for simultaneous photoactivation. In a complementary approach, a holographic fiberscope was developed by coupling an SLM into a fiber with an objective, combining it with one-photon calcium imaging with a micromirror array also delivered to the fiber, which allows simul- taneous photoactivation and readout with near-cellular resolu- tion in freely moving mice (Fig. 3; Szabo et al., 2014). Finally, the development of the new red GECI RCaMP2 has allowed blue- light-activated channelrhodopsins to be combined with readout of activity in freely moving C. elegans (Inoue et al., 2015). To- gether, these experiments have demonstrated the viability of all- optical interrogation in a range of experimental applications for manipulation of neural circuits in behaving animals. The next steps will be to engineer order-of-magnitude improvements in the different elements of the all-optical toolkit—most notably, the parallel development of new sensors and actuators with non- overlapping wavelength spectra and the refinement of optical strategies for light targeting of multiple cells deep in tissue while minimizing excitation of “out-of-focus” neurons expressing the actuators—and then to assess which stimulation strategies (scanning versus parallel) are best suited to different types of experiments.
A photon can provide unmatched high speed and can store the information in a signal of zero mass. These properties of photon have attracted the attention of researchers to implement the reversible logic gates in alloptical domain. In the recent years, researchers have implemented several reversible logic gates in optical computing domain such as Feynman gate, Toffoli gate, Peres gate and Modified Fredkin gate. The alloptical implementation of reversible logic gates can be achieved using semiconductor optical amplifier (SOA) based Mach-Zehnder interferometer (MZI) optical switches.
chirp-rates, which relates to the development of flat spectral-density supercontin- uum sources. Recently, a few techniques based either on similariton generation in highly nonlinear-fibre amplifiers  or parabolic pulse seeding into a conventional highly-nonlinear fibre  have shown flat spectral-density over more than 20 nm. Other techniques that can eventually produce a wider flat spectrum is the shaping of a SPM-broadened spectrum with a dymanic-gain-equaliser, which however can only provide limited spectral shaping. The pre-shaping technique proposed in this thesis is another possibility, but wider spectrum generation requires further investigation. The optical gating of the linearly-chirped pulses at the above speed (160 Gb/s) re- quires the use of an ultrafast switch. Still, the NOLM switch is likely to be the most suitable choice. However, to assure constant switching efficiency over the wide band- width of the linearly-chirped pulses, highly nonlinear fibres with reduced higher-order dispersion terms should be used . A problem that has affected the NOLM switch- ing performance in this thesis experiments is the cross-phase modulation between the counter-propagating signals in the NOLM. This is likely to become a major impair- ment at higher bit-rates, and a NOLM scheme that eliminates the contribution of the counter-propagation XPM should be considered . Another possible solution for the ultrafast gating of linearly-chirped pulses is LiNbO 3 integrated devices . The