In this work optical networks in mesh topology with OPS/OBS photonic switching are analysed and evaluated. Analytical and computer simulation methods are utilised for evaluation of average number of hops (ANH), packet loss fraction (PLF) and transmission delay (latency). These OPS/OBS networks show that under high input traffic, networks with nodes of higher interconnection grade are more efficient than just larger networks (increased number of nodes). For both optical packest and bursts results indicate high throughput, low ANH, low latency and very low packet loss fraction at the optical layer in our networks.
In this paper, the impact of the number of channels on the performance of elastic optical networks (EONs) is examined considering a multilevel modulation format and coherent transmission. Network design parameters such as spectral bandwidth and channel symbol error rate (SER), are analysed. We simulated the transmission of quadrature phase shift-keying (QPSK) signals, modulated at 56 and 100 Gbps, to evaluate a proposed flexible spectral allocation method in order to evaluate the effect of number of channels and the required total spectral bandwidth.
We evaluate through computer simulation the performance of Photonic switching OPS/OBS networks of various sizes and configurations, based on a lossless (amplified) photonic switching node experimentally demonstrated previously. The great advantage of photonic switching is transparency to signal rate and format. Thus we propose a basic flexible network, with low-energy consumption and high-efficiency. In simulations traffic load is varied and network parameters such as, average number of hops (ANH), network latency (delay) and packet loss fraction are evaluated. Consistent results for the various configurations are presented, analyzed and discussed; and Interesting conclusions emerge.
The main proposal of this work is to show the importance of using simulation tools to project optical networks. The simulation method supports the investigation of several system and network parameters, such as bit error rate, blocking probability as well as physical layer issues, such as attenuation, dispersion, and nonlinearities, as these are all important to evaluate and validate the operability of optical networks. The work was divided into two parts: firstly, physical layer preplanning was proposed for the distribution of amplifiers and compensating for the attenuation and dispersion effects in span transmission; in this part, we also analyzed the quality of the transmitted signal. In the second part, an analysis of the transport layer was completed, proposing wavelength distribution planning, according to the total utilization of each link. The main network parameters used to evaluate the transport and physical layer design were delay (latency), blocking probability, and bit error rate (BER). This work was carried out with commercially available simulation tools.
Results and analysis of semiconductor optical amplifiers (SOA) are presented as applied to Photonic switching nodes in OPS/OBS future optical networks. Detailed characterization is provided to investigate physical constraints of optical power, gain and noise figure of SOAs. Two different lasers, one external cavity tunable laser and one DFB laser, verify that although the SOA gain is not significantly sensitive to input source a clear difference on the noise figure (NF) is observed. Another important result is that by limiting the average number of hops in the network accumulated ASE power from the amplifiers should not impair signal quality.
Frequently, assessment and monitoring of mechanical (acoustic) vibrations is necessary in large structures. Cost and reliability are major issues for field-deployment. We present a simple, compact and reliable optical accelerometer designed and constructed in our labs, capable of consistent measurement of vibrations in low and intermediate acoustic ranges (few Hz to few kHz). The principle of operation is based on the variation of the optical signal power coupled between singlemode fibers fixed in the optical sensor head. The device sensitivity has a lower limit to accelerations below 1g, and surprising upper value above 180 m/s<sup>2</sup> (18g).
A new system for generation, switching and routing of optical packets in photonic networks, having 2x2 optical transparent nodes, is described. The optical packets are constituted of a frequency tone header in the low RF range (MHz), and a digital payload which can be of different rates or formats, in the range 1 to 5 Gb/s. Packets can have time frame between 2-6 μs, with separate fields for header and payload; the header field being much shorter than the payload field. The optical packet switch node includes blocking, routing and drop functions, controlled by electronic logic circuits, processing only the header information. Switching is performed on a packet-by-packet basis; and packets are routed according to header frequency allocation, which relates to node output ports and packet destination node addresses. Processing times for header recognition and packet switching are 2 μs. The digital payload remains untouched throughout the network, delivering high-bandwidth to final users, with very low latency in the network, and very small packet loss. This system is designed for application in metro-access next-generation optical networks (NGON), one example being interconnection of high-capacity wireless base stations.
This paper describes an eight channel optical fiber interconnection module based on linear array of lasers and photodiodes and multimode fiber ribbon. From the experimental results the skew was estimated to be lower than 5 ns. No error was observed during a long term test. A twenty-two channel optical interconnection module was implemented based on the eight channel module and it was installed in a TROPICO switching system with no degradation in the performance.