Optical Multistage Networks Research Articles

Power loss analysis in thermally-tuned nanophotonic switch for on-chip interconnect

Nanophotonic is considered an emerging technology for future many-core systems due to its potentials for low-power and high-bandwidth communications. Nevertheless, challenges such as crosstalk noise and temperature variation of photonic devices significantly reduce the optical signal-to-noise ratio which leads to reliability decrease in the optical network on chips. In this paper, we propose a thermally-tuned symmetric optical switch (TTSOS) and analyze its thermal effects. Using thermal-based adjustment in this design leads to reduce power loss under temperature variation. The functionality of the switch is examined through several numerical simulations with 10Gb/s non-return-to-zero signals. The simulation results show the data transmissions at 10Gb/s with low crosstalk and power penalty less than −50 dB and 0.1 dB, at 1.1×10−31 bit error rate, respectively. TTSOS improves the reliability in the resonant wavelength shift of micro-ring resonator, as well as the performance of the optical multi-stage networks. Finally, at the system-level, we systematically study the worst case as well as the average insertion loss in Benes-based optical network-on-chip.

A strictly nonblocking network based on nonblocking 4×4 optical switches

Recently, the demand for communication has been growing rapidly. Hence, optical multistage network technologies are more appreciated nowadays. A double-layer network is a strictly nonblocking network, and it has the lowest system insertion loss of non-dilated networks. A Beneš network is a rearrangeably nonblocking network, and it has the same system insertion loss as a double-layer network. We have proposed the use of modified polarization selection elements (PSEs). The system insertion loss, number of drivers, and number of required components of a double-layer network could be reduced if it is constructed with modified PSEs. A nonblocking 4×4 optical switch with two stages of polarization selective elements has been presented in our previous study. Based on this nonblocking 4×4 optical switch, we propose a strictly nonblocking network structure which features even lower system insertion loss than those of a double-layer network and a Beneš network. The signal-to-noise ratio of the proposed network structure is a constant, and is higher than the constraint, although it is lower than that of the double-layer network. The number of major components of the proposed network is less than that of a double-layer network and larger than that of a Beneš network, since a Beneš network is rearrangeably nonblocking. We also offer a routing algorithm for the new proposed network; the time complexity of the routing algorithm is O ( 1 ) .

Simulated annealing routing and wavelength lower bound estimation on wavelength-division multiplexing optical multistage networks

Multistage interconnection networks (MINs) are popular in switching and communication applications and have been used in tele- communication and parallel computing systems for many years. Crosstalk a major problem introduced by an optical MIN, is caused by coupling two signals within a switching element. We focus on an efficient solution to avoiding crosstalk by routing traffic through anN3N optical network to avoid coupling two signals within each switching element us- ing wavelength-division multiplexing (WDM) and a time-division ap- proach. Under the constraint of avoiding crosstalk, the interest is on realizing a permutation that uses the minimum number of passes for routing. This routing problem is an NP-hard problem. Many heuristic al- gorithms are already designed by researchers to perform this routing such as a sequential algorithm, a degree-descending algorithm, etc. The genetic algorithm is used successfully to improve the performance over the heuristic algorithms. The drawback of the genetic algorithm is its long running times. We use the simulated annealing algorithm to improve the performance of solving the problem and optimizing the result. In addition, a wavelength lower bound estimate on the minimum number of passes required is calculated and compared to the results obtained using heu- ristic, genetic, and simulated annealing algorithms. Many cases are tested and the results are compared to the results of other algorithms to show the advantages of simulated annealing algorithm. © 2004 Society of

Optimal all-to-all personalized exchange in a class of optical multistage networks

All-to-all personalized exchange is one of the most dense collective communication patterns and it occurs in many important parallel computing/networking applications. In this paper, we look into the issue of realizing an all-to-all personalized exchange in a class of optical multistage networks. Advances in electrooptic technologies have made optical communication a promising networking choice to meet the increasing demands for high channel bandwidth and low communication latency of high-performance computing/communication applications. Although optical multistage networks hold great promise and have demonstrated advantages over their electronic counterpart, they also hold their own challenges. Due to the unique properties of optics, crosstalk in optical switches should be avoided to make them work properly. In this paper, we provide a systematic scheme for realizing an all-to-all personalized exchange in a class of unique-path optical multistage networks crosstalk-free. The basic idea of realizing an all-to-all personalized exchange in such a multistage network is to transform it to multiple semipermutations and ensure that each of them can be realized crosstalk-free in a single pass. As can be seen, the all-to-all personalized exchange algorithm we propose has O(n) time complexity for n processors, which is optimal for an all-to-all personalized exchange. The optimal time complexity combined with the property of a single input/output port per processor suggests that a multistage network could be a better choice for implementing an all-to-all personalized exchange due to its shorter communication latency and better scalability.

Field-programmable smart-pixel arrays: design, VLSI implementation, and applications

A smart-pixel array is a two-dimensional array of optoelectronic devices that combine optical inputs and outputs with electronic processing circuitry. A field-programmable smart-pixel array (FP-SPA) is a smart-pixel array capable of having its electronic functionality dynamically programmed in the field. Such devices could be used in a diverse range of applications, including optical switching, optical digital signal processing, and optical image processing. We describe the design, VLSI implementation, and applications of a first-generation FP-SPA implemented with the 0.8-microm complementary metal-oxide semiconductor-self-electro-optic effect device technology made available through the Lucent Technologies-Advanced Research Projects Agency Cooperative (Lucent/ARPA/COOP) program. We report spice simulations and experimental results of two sample applications: In the first application, we configure this FP-SPA as an array of free-space optical binary switches that can be used in optical multistage networks. In the second, we configure the device as an optoelectronic transceiver for a dynamically reconfigurable free-space intelligent optical backplane called the hyperplane. We also describe the testing setup and the electrical and the optical tests that demonstrate the correct functionality of the fabricated device. Such devices have the potential to reduce significantly the need for custom design and fabrication of application-specific optoelectronic devices in the same manner that field-programmable gate arrays have largely eliminated the need for custom design and fabrication of application-specific gate arrays, except in the most demanding applications.

Design of space-multiplexed three-dimensional Omega networks and their optical implementation

A method is described for arrangement of channels from different stages of a three-dimensional shuffle/exchange network so that only a single set of optics is needed to perform the two-dimensional shuffles. This arrangement is based on our earlier one-copy algorithm. It requires a feedback system and is an example of a space-multiplexed optical multistage network. We discuss the design issues and experimental results.