Free-space optical backplane prototype for telecommunication equipment in the petabit/s range

The system performance of data- and telecommunication equipment must keep up with the increasing network speed. Optical interconnections technology is a promising alternative for high-throughput systems. We demonstrate the optical backplane system using a waveguide-embedded optical backplane and two processing boards. The transmitter and receiver modules were prepared for optical printed circuit boards (PCBs), which consists of the metal optical bench, the driver chips, vertical-cavity surface-emitting lasers (VCSELs), photodiodes, and a tapered polymeric waveguide. We report high-speed transmission of 27–1 pseudorandom bit sequence (PRBS) nonreturn to zero (NRZ) data up to 10 Gbits/s through the optical backplane system. The results demonstrate that the optical backplane system can be practical and valuable for the future high-throughput systems by using metal optical bench and precisely machined optical plug-adaptor structure to achieve stable board-to-board interconnection.

Current high performance switching and computing systems rely on an electrical interconnection network to transport information throughout the system for chip-to-chip and board-to-board communications [1]. This network however is limited relative to the bandwidth, connectivity, power consumption, and latency it offers. Because the aggregate bandwidth of the integrated circuits inside these systems continues to increase, so must the system's interconnection capabilities [2], The intrinsic limitations of current and projected electrical interconnection networks has lead system designers to consider optical interconnects deployed "inside the box" as a way of increasing system performance [3]. An optical backplanes is an example of such a system. The identification of critical issues in free-space optical backplanes is being pursued in the form of system demonstrator experiments [4-10]. Through the construction of several system demonstrators an iterative design, analysis, and implementation procedure has been used to address the critical issues associated with deploying optical interconnections at the board-to-board level. This talk will highlight the challenges and choices associated with the demonstrators.

In the next years, when the data throughput in the telecom equipment will increase, the electrical interconnections among the boards in a subrack will be a bottleneck for the signal transmission. For transmitting digital data at several tents of Gbps, it will be needed to pass to a transmission layer completely optical, where optical boards will be interconnected in the same subrack by means of optical backplanes. Actually the optical backplane design and manufacturing involves very sophisticated and expensive technologies. In this paper an example of low cost solution for optically interconnecting different boards in the same subrack is presented, highlighting the benefit from the data transmission point of view.

Optical backplanes are attractive components for systems with high data rates between subsystems and a large number of interconnects. An optical backplane which uses multimode polymer waveguides was originally developed for avionic applications but can be used in telecom switching systems as well. For transmission distances in the range of 100cm and data rates up to 10Gbps, the modal dispersion can be negelected. The waveguides are fabricated on large substrates (aluminum, FR4 and others) by a direct writing technique. Splitters and couplers can be fabricated with the same technique. The waveguides have a low loss (0.04dB/cm) and high temperature stability (up to 250°C) and are used with 840nm vertical cavity lasers. The waveguide cross section can be chosen between approx. 250μm x 250μm and 50μm x 50μm. We have successfully transmitted up to 10Gbit/s over multimode polymer waveguides with lengths of 100cm. A free space, expanded beam coupling is used for the board-backplane transition, resulting in high alignment tolerances. The overall insertion loss for a backplane connection is typically between 2 and 8 dB, depending on waveguide length, radius of curvature, number of waveguide crossings etc. A typical transceiver power budget of 15-20dB allows the integration of star couplers with up to 16 ports. Several test systems with different interconnection schemes have been realized and tested. Tests include mechanical stability (vibration), thermal stability (cycles, shocks and accelerated aging) and gamma irradiation as well as optical power levels, signal integrity and bit error rates.

Future bandwidth needs force the development of optical interconnects for data transmission at board level. The aim is to develop technology solutions for embedded optical architectures in data center and network systems to allow significant reduction in power consumption, increased energy efficiency, system density and bandwidth scalability, which is currently unfeasible in today's copper driven systems. A passive optical backplane comprising a printed circuit board (PCB) with integrated optical waveguides and standardized pluggable optical coupling interfaces to the line cards is proposed for future data communication systems. Our activities are focused on embedded glass-based electro-optical circuit boards (EOCB) with integrated gradient-index multimode waveguides, which exhibit very low propagation loss at key optical communication wavelengths. A pre-processed glass panel with planar integrated optical waveguides is embedded into a backplane by using proven industrial PCB processes. A pluggable optical connector and receptacle system is designed for connecting the optical fiber links of the line cards with the optical waveguide circuit of the backplane.

A performance comparison between the electrical Cu-based backplane and a full-optical fiber-based backplane is presented in terms of capacity and power consumption. By means of systematic simulations we find the electrical configuration, which allows to optimize the Cu-based backplane by exploiting the best technologies available today. On the other hand, a fiber-based optical backplane is proposed by exploiting the most performing VCSEL sources. Limitations of the electrical and optical approaches are discussed, considering their capabilities to support up to about 25-Gb/s transmission and the possibility to evolve towards higher bit-rates.

In the context of the implementation of the main strategic goal of national development — digital transformation, the tasks of intensive implementation of information technologies in the business processes of enterprises come to the fore. To optimize this process, it is important to correctly determine the strategic direction of the enterprise development and choose a business model for digital transformation. The article deals with issues related to the assessment of the digital maturity of an enterprise. The possibility of using the indicators of the development of the information society of the Russian Federation to create a model of an integral indicator for assessing digital maturity is determined. The question of the interdependence of development indicators in the sections on the availability of financial resources and e-business is considered in detail. The studies are carried out using the method of pairwise correlation analysis based on the data of federal statistical observations on the issues of monitoring the development of the information society in the Russian Federation. In general, the impact of 29 out of 32 indicators from the "Electronic Business" section, which have a sufficient amount of statistical data, on the indicator "Volume of investments in fixed assets directed to information, computer and telecommunications equipment" was studied. Only two of them (The share of organizations that had special software for managing the purchase of goods (works, services), in the total number of surveyed organizations and the share of organizations that had special software for managing the sale of goods (works, services), in the total number of surveyed organizations) show little or no correlation. The rest demonstrate the tightness of the correlation from noticeable to very high. The identified indicators from the e-business section, which have stable relationships with the indicator "Volume of investments in fixed assets aimed at the acquisition of information, computer and telecommunications equipment", will be further included in the integral indicator for assessing the digital maturity of an enterprise, which allows for a quantitative assessment based on the model multiple regression.

Our paper proposes significant changes to AI technology. We believe this is necessary because current implementations have stagnated at average error rates of approximately 8%. Implementers hope that further improvements will lower error rates to 5% by 2025. This would require 1028 floating-point operations, which is not possible with today’s algorithms and computer technology. Even errors of 5% are excessive for many practical applications. The current AI implementations have ignominious errors. Near bankruptcy of a prominent real estate corporation, and the obligatory resignation of an elected government official resulted from AI errors. The causation errors were ludicrous and unlikely performed by humans. Applications of AI are therefore limited to those for which errors are nugatory. In contrast, the human brain’s capabilities and efficiency are astonishing. In significant contrast to current AI models, the human brain is impressive in terms of its relatively small size (adult average 79 in3), weight (approximately 4#), and power consumption (nominally 15W). We feel that this implies that AI technology needs to adopt excluded neurological properties. The current AI neuron model is an overly simplified linear model, which was proposed about 70 years ago. We propose emulating the neurological neuron’s nonlinear capabilities. The versatility of the improved AI model would be many orders of magnitude beyond that of the currently implemented linear neuron models. Also, the proposed neurological properties are of neural plasticity. Specifically, we describe the neurological associative learning aspect of neuroplasticity, partitioning associative plasticity into “inter-association” (neural network structure), and “intra-association” (neuron functioning).

Vapor compression systems have technical limitations to reduce power consumption and environmental effects due to chemical refrigerants. Therefore, we are paying attention to a membrane air-conditioning system using water as a refrigerant. Since there is no chemical refrigerator and compressor, power consumption of the membrane air-conditioning system can be greatly reduced and there is no environmental impact such as global warming. A dehumidifying nanocomposite membrane has been developed. Since this dense membrane has hydrophilic nanochannel, water vapor can be permeated. Therefore, if a difference in water vapor partial pressure occurs using a vacuum pump, this membrane can remove moisture from the supply air. We built a permeability testing device of the developed membrane. The test cell was placed in a thermo-hygrostat bath. The flow rate, temperature and relative humidity at the inlet and outlet of the test cell were measured and recorded. The water vapor permeability through the membrane was measured to 50 g/m2h/kPa. The membrane dehumidification module was designed based on this experimental result and assembled with an IEC (indirect evaporative cooler) module for integrating the air-conditioning system. The cooling capacity measured up to 1.2 kW. The feasibility of the membrane air conditioning system has been demonstrated.

A guided-wave optical backplane bus system intended for use in high-performance board-to-board interconnects is described. Its multiplexed polymeric holograms can implement optical signal broadcast between boards so that all boards share common optical channels. By introducing an active coupler to the doubly multiplexed hologram at the center board, signals received from any board can be rebroadcast to all other boards. We describe the design concepts for a centralized optical backplane and the resulting performance and assembly advantages over previously developed guided-wave and free-space optical backplane bus systems used for broadcasting signals. These advantages include equalized fan-out power, increased interconnect distance, and simpler fabrication.

The phase variation characteristics of emissions radiated from telecommunication equipment were examined to determine how much the radiated emission will increase when the number of devices or their size increases. Simulation using an extrapolation model in which the devices are represented as wave sources expressed as current sources (whose phase varied randomly) showed that the characteristics are close to a power sum. Experiments showed that the harmonics of radiated emissions from actual equipment had large phase variations. The experimental results were close to the calculated ones. The radiated emission strength of large-scale telecommunication equipment can be estimated from the emission strength of a single device.

This paper considers the problem of synthesizing application-specific network-on-chip (NoC) architectures. We propose two heuristic algorithms called CLUSTER and DECOMPOSE that can systematically examine different set partitions of communication flows, and we propose Rectilinear-Steiner-tree (RST) based algorithms for generating an efficient network topology for each group in the partition. Different evaluation functions in fitting with the implementation backend and the corresponding implementation technology can be incorporated into our solution framework to evaluate the implementation cost of the set partitions and RST topologies generated. In particular, we experimented with an implementation cost model based on the power consumption parameters of a 70 nm process technology where leakage power is a major source of energy consumption. Experimental results on a variety of NoC benchmarks showed that our synthesis results can on average achieve a 6.92 x reduction in power consumption over the best standard mesh implementation. To further gauge the effectiveness of our heuristic algorithms, we also implemented an exact algorithm that enumerates all distinct set partitions. For the benchmarks where exact results could be obtained, our CLUSTER and DECOMPOSE algorithms on average can achieve results within 1% and 2% of exact results, with execution times all under 1 second whereas the exact algorithms took as much as 4.5 hours.

A 2-D neural network and its optical implementation are presented. The neural network consists of two interconnection layers. The first layer is a modified Hamming net layer that calculates the Hamming distance between the input and each of the stored patterns. Instead of performing a winner-take-all operation, thresholding is performed within each hidden neuron. The second layer is a mapping network for pattern association. The presented neural network has fewer interconnections and a higher storage capacity than a fully interconnected Hopfield network. In comparison with multilayer perceptrons, it has advantages such as easy and direct training and unipolar binary interconnection weights and therefore is more suitable for optical implementation with currently available optoelectronic devices. The neural network can be easily reconfigured when the training set needs to be updated or extra training patterns need to be added into the training set. The attraction basins of stored patterns can be adjusted, and the input fault tolerance can be enhanced locally. An optical system employing Dammann gratings has been used in the preliminary experiments. Experimental results verified the feasibility of the neural network model as well as its optical implementation.

In this paper, we present the novel scheduling algorithm of the multimedia data retrieval for the mobile disk drive. Our algorithm is focused on minimizing the power consumption in multimedia data retrieval. While the disk based storage devices, e.g. hard disk and optical disk becomes small enough to be used in mobile devices, the practical usage of which leaves much to be desired due to the stringent power consumption restriction of the mobile device. The playback of multimedia data requires that data blocks are delivered to the destination in periodic fashion. The major issue here has been how to guarantee the continuous flow of data. Most of preceding works assume that the disk drive always operates in the steady state. However, this does not hold in modern disk drive for the mobile device. Modern low power disk drive for mobile device goes into standby state when it is not in use. While this feature can significantly extend the battery life, it adds another dimension of complexity in scheduling of the multimedia data retrieval. We elaborately model the power consumption behavior of the low power mobile drive and develop an Adaptive Round Merge(ARM) scheduling algorithm which guarantees a certain disk bandwidth for the multimedia playback while minimizing the power consumption of the storage device. According to our simulation based experiment, the ARM algorithm reduces the power consumption by as much as 23%. It manifests itself when the video clip is relatively short, typically less than 30 sec.

Recent experimental advances in preparing regular defect-free 2D arrays of atoms with optical traps have offered new opportunities to engineer strong collective couplings between light and atoms as quantum optical dipoles. Applications of such collective light-matter interactions include the realization of atom-thick mirrors, retrieval of quantum memories with high efficiency, or the implementation of topological quantum optics. I will present novel applications in the context of quantum networking. First, I will discuss the design of a chiral photonic quantum link, where distant single atoms interact by exchanging photons propagating in a unique direction in free space. This is achieved by coupling both single atoms, representing qubits implemented using a pair of Rydberg states, to bi-layer atomic arrays which act as quantum phased-array antennas. Exploiting the combination of a “Rydberg-dressing” laser and a control laser driving the atomic arrays, an effective Rydberg dipole-dipole interaction can be engineered between atoms and atomic arrays as quantum emitters, allowing to match the spatial modes of spontaneously emitted and absorbed photons to a Gaussian mode of interest. In this way, we realize a chiral quantum interface, i.e., where atoms couple to photonic modes with a unique direction of propagation. This setup provides a basic building block of a novel platform for quantum networks in free space, i.e., without requiring coupling atoms to modes of cavities or nanostructures, which I will illustrate with the deterministic coherent transfer of quantum states between single atoms with high fidelity. Second, I will discuss the collective radiation properties of two distant single-layer atomic arrays acting as quantum memories. This system can support a long-lived non-local superposition state of atomic excitations exhibiting strong subradiance. This “dark” mode consists of an atomic excitation which is delocalized between the two distant atomic arrays, in such a way that the overall radiation is strongly suppressed by quantum interference. I will describe the preparation of these states and their application as resource of non-local entanglement. In particular, by weakly driving the arrays, the state of the quantum memories, localized in each array, can be transferred to this “non-local” subradiant state, allowing again for a deterministic coherent quantum state transfer with high fidelity between the memories. Finally, I will discuss experimental realizations using cold atoms in optical trap arrays, and the effect of experimental imperfections in the arrays, such as finite defect probability, temperature, and depth of the optical traps.