Switch Fabric Research Articles

Quantum computation with photochromic films in a Mach–Zehnder interferometer

Photochromic materials are of great interest because they enable the fabrication of photo-activated switches. In this study, an experiment is proposed in which two chromene-based photochromic layers were inserted into the arms of a Mach–Zehnder interferometer. The chromene was studied from the perspective of optical absorption to determine the wavelength-dependent complex refractive index. Impinging ultraviolet light on one of the chromene layers induces a transition from the closed to the open form of the chromene, resulting in different phase shifts in the two arms of the interferometer. This results in a change in the probability of detecting a photon by the two detectors after the second mirror of the Mach–Zehnder interferometer. The experiment may be of interest to researchers working in the fields of quantum information and quantum communications.

Nanophotonic structure inverse design for switching application using deep learning

Switching functionality is pivotal in advancing communication systems, serving as a paramount mechanism. Despite numerous innovations in this field, optical switch design, fabrication, and characterization have traditionally followed an iterative approach. Within this paradigm, the designer formulates an informed conjecture regarding the switch's structural configuration and subsequently resolves Maxwell's equations to ascertain its performance. Conversely, the inverse problem, which entails deriving a switch geometry to achieve a targeted electromagnetic response, continues to pose formidable challenges and necessitates substantial time and effort, particularly under the constraints of specific assumptions. In this work, we propose a deep neural network-based method to approximate the spectral transmittance of all-optical switches. The findings substantiate the efficacy of deep learning in the design of all-optical plasmonic switches, which are renowned as the fastest switches at the nanoscale. The nonlinear Kerr effect in square resonators is leveraged to demonstrate the switching performance. Juxtaposed with conventional simulations, the proposed model showcases a remarkable improvement in computational efficiency. Furthermore, deep learning can resolve nanophotonic inverse design problems without reliance on trial-and-error or empirical strategies. Compared to simulations, the mean squared error for both forward and inverse models is meager, with values of around 0.03 and 0.02, respectively. The deep learning-proposed switches exhibit excellent suitability for integration into photonic integrated circuits, substantially influencing the progression of all-optical signal processing.

A fully textile-based, tunable, force and strain sensing resistor for e-textile applications

This work presents a novel approach towards integrating electronic components with textiles, by successfully creating a fully textile-based element that is capable of detecting applied forces by variation in its resistance value. The fabrication of the device consists of a specialized siliconized conductive fabric, which is placed above and below a layer of switch fabric, which acts as a force sensor. In this paper, the effects of three different geometries are observed, as well as the washability of the device, along with tension testing. Μoreover, the device behavior is simulated as well as applied in a real-life scenario. The proposed element demonstrates a good dynamic range, high repeatability and stability, and minimal impact of washing, creating a great candidate for integration in e-textiles.

Fully printed memristors made with MoS2 and graphene water-based inks.

2-Dimensional materials (2DMs) offer an attractive solution for the realization of high density and reliable memristors, compatible with printed and flexible electronics. In this work we fabricate a fully inkjet printed MoS2-based resistive switching memory, where graphene is used as top electrode and silver is used as bottom electrode. Memristic effects are observed only after annealing of each printed component. The printed memory on silicon shows low SET/RESET voltage, short switching times (less than 0.1 s) and resistance switching ratios of 103-105, comparable or superior to the performance obtained in devices with both printed silver electrodes on rigid substrates. The same device on Kapton shows resistance switching ratios of 102-103 and remains stable at least up to 2% of strain. The memristor resistance switching is attributed to the formation of Ag conductive filaments, which can be suppressed by integrating graphene grown by chemical vapour deposition (CVD) onto the silver electrode. Temperature-dependent electrical measurements starting from 200 K show that memristic behavior appears at a temperature of ∼300 K, confirming that an energy threshold is needed to form the conductive filament. This work shows that inkjet printing is a very powerful technique for the fabrication of 2DMs-based resistive switches onto rigid and flexible substrates.

Micro-transfer printing InP C-band SOAs on advanced silicon photonics platform for lossless MZI switch fabrics and high-speed integrated transmitters.

We present an approach for the heterogeneous integration of InP semiconductor optical amplifiers (SOAs) and lasers on an advanced silicon photonics (SiPh) platform by using micro-transfer-printing (µTP). After the introduction of the µTP concept, the focus of this paper shifts to the demonstration of two C-band III-V/Si photonic integrated circuits (PICs) that are important in data-communication networks: an optical switch and a high-speed optical transmitter. First, a C-band lossless and high-speed Si Mach-Zehnder interferometer (MZI) switch is demonstrated by co-integrating a set of InP SOAs with the Si MZI switch. The micro-transfer-printed SOAs provide 10 dB small-signal gain around 1560 nm with a 3 dB bandwidth of 30 nm. Secondly, an integrated transmitter combining an on-chip widely tunable laser and a doped-Si Mach-Zehnder modulator (MZM) is demonstrated. The laser has a continuous tuning range over 40 nm and the transmitter is capable of 40 Gbps non-return-to-zero (NRZ) back-to-back transmission at wavelengths ranging from 1539 to 1573 nm. These demonstrations pave the way for the realization of complex and fully integrated photonic systems-on-chip with integrated III-V-on-Si components, and this technique is transferable to other material films and devices that can be released from their native substrate.

Low-power and wide-band 1 × 8 silica waveguide optical switch

A silica waveguide 1 × 8 thermo-optic switch consisting of cascaded three-stage Mach-Zehnder interferometers (MZIs) is demonstrated. The multimode interference (MMI) coupler is adopted in the MMI-MZI 1 × 2 switch unit due to its insensitivity to wavelength and favorable fabrication tolerance. Beam propagation method (BPM) is used in the switch design and optimization. Standard CMOS technologies have been adopted in the preparation of switch fabric. At 1550 nm, the measurement results of 1 × 8 switch show that the fiber-to-fiber insertion loss ranges from 3.4 to 3.6 dB for all routing states. Meanwhile, the extinction ratio is no less than 15.63 dB, and the crosstalk is restrained to be lower than −15.65 dB. Due the adoption of MZI structure, the average driving power for the channel switching is 315.8 mW. Within the wavelength range from 1500 to 1620 nm, the extinction ratio is larger than 15.06 dB, the insertion loss is less than 5.8 dB, and PDL is smaller than 1.18 dB for all routing states. The experimental results fit the simulations well, which proves the proposed switch good potentials in wideband applications.

Controllable fluorescent switch based on ferrocene derivatives with AIE-active tetraphenylethene moiety

Stimuli-responsive supramolecular materials have attracted much attention because of their controllable microstructure and luminescence behavior. In this study, the fluorescent molecule ((1E)-1-((4-(1,2,2-triphenylvinyl)benzylidene)hydrazineylide-ne)ethyl)ferrocene (FcMe-TPE) with aggregation-induced emission (AIE) property and redox activity was synthesized. The morphology as well as fluorescence behavior could be modulated by changing solvent, adding oxidant or applying voltage, and the translation mechanism was explored in detail by means of density functional theory (DFT). Based on the presence of competitive hydrogen bonding, FcMe-TPE assemblies showed different aggregate behaviors and properties under different water contents (fw). As fw increased from 20% to 60%, the morphology of assemblies could be transformed from 2D sheet to elliptical crystal structure, then the precipitation gradually disappeared for the further increase of fw. At the same time, the addition of oxidant as well as the application of voltage could also cause changes in the fluorescence intensity of the assemblies. When the voltage increased from 0 V to 3 V, the fluorescence intensity increased and reached the maximum value at 1 V. Based on this property, the electrofluorochromic (EFC) device with low trigger voltage was made. This work provides a feasible strategy for controllable self-assembly and the fabrication of multiple fluorescence switches, which has potential practical application in the field of advanced anti-counterfeiting, intelligent display and information encryption.

Multicast Space-Conversion-Space Strict-Sense Nonblocking Switching Fabrics with Multicast Opportunity in the Last Stage for Continuous Multislot Connections

This paper introduces two nonblocking switching fabric architectures designed for multicast connections. These connections are defined using the multislot connection approach, mainly applied in elastic optical networks. In contrast to earlier solutions, this approach assumes that multislot connections are consistently established in adjacent continuous slots. This implies that previously established solutions could not be applied. Our study presents a comprehensive theoretical framework applicable to the general case of three-stage switching fabrics. These fabrics feature external stages equipped with space switches, while the middle stage incorporates conversion switches that operate in the wavelength, time, or frequency domain. In addition, multicast capabilities are deliberately confined to the output-stage switch or switches. A fundamental contribution of this work lies in the formulation of the worst-case scenario, which serves as the foundational basis for deriving strict-sense nonblocking conditions governing such multicast switching fabrics. Our analysis formally demonstrates that the fundamental structure of the multicast nonblocking switching fabric aligns closely with that of the previously examined point-to-point fabric. The only difference is related to the ability to multicast within the output stage of the switching fabric.

Harnessing self-heating effect for ultralow-crosstalk electro-optic Mach–Zehnder switches

This paper presents a novel approach to counterbalance free-carrier-absorption (FCA) in electro-optic (E-O) Mach–Zehnder interferometer (MZI) cells by harnessing the self-heating effect. We show insights on crosstalk limitations in MZIs with direct carrier-injection and provide a detailed design methodology on a differential phase shifter pair. Leveraging both free-carrier dispersion (FCD) and self-heating effects, our design enables arbitrary phase tuning with balanced FCA loss in the pair of arms, eliminating the need for additional phase corrections and creating ultralow crosstalk MZI elements. This neat design disengages from the commonly used nested structure, thus providing an opportunity of embedding tunable couplers for correcting imperfect splitting ratios given that only two are needed. We show that with the use of tunable directional couplers, a standard ±10 nm process variation is tolerated, while achieving a crosstalk ratio below −40 dB. By direct carrier injection in both arms, the proposed device operates at nanosecond scales and can bring about a breakthrough in the scalability of E-O switch fabrics, as well as other silicon integrated circuits that have stringent requirements for crosstalk leakage.

A Controller for Si MZI-Based Spanke-Benes Optical Switch Fabric With Automatic Calibration Capability

A Controller for Si MZI-Based Spanke-Benes Optical Switch Fabric With Automatic Calibration Capability

Ultra-low-loss multi-layer 8 × 8 microring optical switch

Microring-based optical switches are promising for wavelength-selective switching with the merits of compact size and low power consumption. However, the large insertion loss, the high fabrication, and the temperature sensitivity hinder the scalability of silicon microring optical switch fabrics. In this paper, we utilize a three-dimensional (3D) microring-based optical switch element (SE) on a multi-layer Si3N4-on-SOI platform to realize high-performance large-scale optical switch fabrics. The 3D microring-based SE consists of a Si/Si3N4 waveguide overpass crossing in the bottom and the top layers, and Si3N4 dual-coupled microring resonators (MRRs) in the middle layer. The switch is calibration-free and has low insertion loss. With the 3D microring-based SEs, we implement an 8×8 crossbar optical switch fabric. As the resonance wavelengths of all SEs are well aligned, only one SE needs to be turned on in each routing path, which greatly reduces the complexity of the switch control. The optical transmission spectra show a box-like shape, with a passband width of ∼69 GHz and an average on-state loss of ∼0.37 dB. The chip has a record-low on-chip insertion loss of 0.52–2.66 dB. We also implement a non-duplicate polarization-diversity optical switch by using the bidirectional transmission characteristics of the crossbar architecture, which is highly favorable for practical applications. 100 Gb/s dual-polarization quadrature-phase-shift-keying (DP-QPSK) signal is transmitted through the switch without significant degradation. To the best of our knowledge, this is the first time that 3D MRRs have been used to build highly scalable polarization-diversity optical switch fabrics.

Simultaneous Connections Routing in Wavelength–Space–Wavelength Elastic Optical Switches

In this paper, we investigate the three-stage, wavelength-space-wavelength switching fabric architecture for nodes in elastic optical networks. In general, this switching fabric has r input and output switches with wavelength-converting capabilities and one center-stage space switch that does not change the spectrum used by a connection. This architecture is most commonly denoted by the WSW1 (r, n, k) switching network. We focus on this switching fabric serving simultaneous connection routing. Such routing takes place mostly in synchronous packet networks, where packets for switching arrive at the inputs of a switching network at the same time. Until now, only switching fabrics with up to three inputs and outputs have been extensively investigated. Routing in switching fabrics of greater capacity is estimated based on routing in switches with two or three inputs and outputs. We now improve the results for the switching fabrics with four inputs and outputs and use these results to estimate routing in the switching fabric with an arbitrary number of inputs and outputs. We propose six routing algorithms based on matrix decomposition for simultaneous connection routing. For the proposed routing algorithms, we derive criteria under which they always succeed. The proposed routing algorithms allow the construction of nonblocking switching fabrics with a lower number of wavelength converters and the reduction of the overall switching fabric cost.

Multicolor Adjustable B-N Molecular Switches: Simple, Efficient, Portable, and Visual Identification of Butanol Isomers.

As intelligent probes, dynamic and controllable molecular switches are useful tools for probing and intervening in life processes. However, the types and properties of molecular switches are still relatively single and often can only make two actions: "off" and "on". Therefore, the development of novel molecular switches with multiple colors and multiple instructions is very challenging. Herein, we propose a novel strategy based on the instability of the Lewis acid-base pair (boron (B) and nitrogen (N)), such as introducing the Schiff base (C═N) group into the aminoborane skeleton and preparing the novel molecular switches BN-HDZ and BN-HDZ-N. These two molecules were found to have good multicolor fluorescence switching capability for methanol. Surprisingly, the compound BN-HDZ-N shows unprecedented visual identification for the butanol isomers and could be made into a portable strip for simple and rapid visual identification of the four isomers of butanol, promising an alternative to conventional Lucas reagents. This provides a novel strategy for the design and fabrication of novel multicolor-tunable molecular switches with visual identification of isomers.

A Future Proof Reconfigurable Wireless and Fixed Converged Optical Fronthaul Network Using Silicon Photonic Switching Strategies

Broadband access services in the era of 5G and beyond are driving the evolution of optical access networks from a fiber-to-the-home/ fiber-to-the-building infrastructure to a more common access platform, compatible with both wired and wireless broadband services. Accordingly, a flexible optical access network plays a pivotal role in catering to various service requirements. This work proposes a reconfigurable converged optical fronthaul network for wireless and wired services using a 4◊4 microring resonator (MRR) based silicon photonic (SiP) switch fabric. Reconfigurable service selection is demonstrated for wavelength selective, multicast and space switching scenarios. The reconfiguration of digital data and digital radio-over-fiber (DRoF) services for cloud radio access networks (C-RAN) is demonstrated.

Enhancing meta slot space space wavelength to solve blocking case in elastic optical networks

Elastic optical networks (EONs) are a promising technology for the development of flexible and wideband communication systems. The (FSU) frequency slot unit concept is used in this technology to define the bandwidth unit in the frequency domain. The use of a specified number of consecutive FSUs allows bandwidth to be assigned to a data stream in a flexible manner. Nonblocking optical switching networks are required for a successful elastic optical network operation. This article concentrates on the Wavelength Space Wavelength,Space, Wavelength switching network topologies that were previously presented. In comparison to the other architectures, the SSW switching fabric requires fewer Spectrum converters (SCs). n relation to Wavelength Space Wavelength, a prior study clarified that using the meta-slot approach reduces hardware complexity, which is measured by the number of frequency slot unit. A frequency range with one or more (FSUs) is called a meta-slot. The previous study did not discuss how to optimize the meta-slot class sizes, despite the fact that its effectiveness depends on the sizes of the meta-slot classes. Additionally, the use of meta-slots for Space Space Wavelength was not taken into account in the earlier analysis. The optimization of meta-slot class sizes is looked into in this study, and it is shown that this optimization may be modeled as the shortest path issue. For Wavelength Space Wavelength, the previously reported nonblocking conditions are contrasted with the meta-slot scheme optimized using the shortest path model. The outcome attests to the optimized meta-slot scheme's superiority. The distribution of meta-slots among S-switches is also crucial for Space Space Wavelength. The assignment of meta-slots is modeled as a bin-packing problem in the study. Thus, a well-known bin-packing heuristic can be used to find the assignment that is close to ideal. The number of S-switches is calculated for using the optimized meta-slot scheme and previously known nonblocking conditions. The outcome confirms that the meta-slot scheme benefits both Space, Wavelength and Wavelength Space Wavelength.

Design and Analysis of a Fluid-Filled RF MEMS Switch

In the present study, a fluid-filled RF MEMS (Radio Frequency Micro-Electro-Mechanical Systems) switch is proposed and designed. In the analysis of the operating principle of the proposed switch, air, water, glycerol and silicone oil were adopted as filling dielectric to simulate and research the influence of the insulating liquid on the drive voltage, impact velocity, response time, and switching capacity of the RF MEMS switch. The results show that by filling the switch with insulating liquid, the driving voltage can be effectively reduced, while the impact velocity of the upper plate to the lower plate is also reduced. The high dielectric constant of the filling medium leads to a lower switching capacitance ratio, which affects the performance of the switch to some extent. By comparing the threshold voltage, impact velocity, capacitance ratio, and insertion loss of the switch filled with different media with the filling media of air, water, glycerol, and silicone oil, silicone oil was finally selected as the liquid filling medium for the switch. The results show that the threshold voltage is 26.55 V after filling with silicone oil, which is 43% lower under the same air-encapsulated switching conditions. When the trigger voltage is 30.02 V, the response time is 10.12 μs and the impact speed is only 0.35 m/s. The frequency 0-20 GHz switch works well, and the insertion loss is 0.84 dB. To a certain extent, it provides a reference value for the fabrication of RF MEMS switches.

Fault Tolerant Gamma-Minus Network

In large-scale supercomputers thousands of processors are connected together to their respective memory modules which are controlled by several control units connected in parallel. Large data streams have to be communicated between these processors and memories through interconnection networks. Multistage interconnection network (MIN) is an efficient way to provide these communications at a very reasonable cost. For such large systems MIN employed should be highly reliable and fast to meet the desired specifications of these high speed switch fabrics. In this paper two new architectures of MIN are proposed which are named as fault-tolerant Gamma-Minus (FTGM-1 & FTGM-2) networks. These proposed architectures are multipath MIN with totally disjoint paths and are highly reliable and fault tolerant. The routing algorithm proposed for these structures is simple distance tag routing with non-backtracking which overcomes rerouting overheads and hence improve communication delays. The proposed MIN ensures multiple fault tolerance at each stage including input and output stage with minimal horizontal distance between source node to destination node. For validating the results, a comparison has been presented between existing MINs with these proposed designs. The proposed MINs outperform the existing MIN in terms of reliability, fault tolerance and up to some extent cost as well.

Fabrication of electronic switches based on low-dimensional nanomaterials: a review

Fabrication of electronic switches based on low-dimensional nanomaterials: a review

N譔 Clos Digital Cross-Connect Switch Using Quantum Dot Cellular Automata (QCA)

Quantum dot cellular automata (QCA) technology is emerging as a future technology which designs the digital circuits at quantum levels. The technology has gained popularity in terms of designing digital circuits, which occupy very less area and less power dissipation in comparison to the present complementary metal oxide semiconductor (CMOS) technology. For designing the routers at quantum levels with non-blocking capabilities various multi-stage networks have been proposed. This manuscript presents the design of the N×N Clos switch matrix as a multistage interconnecting network using quantum-dot cellular automata technology. The design of the Clos switch matrix presented in the article uses three input majority gates (MG). To design the 4 × 4 Clos switch matrix, a basic 2 × 2 switch architecture has been proposed as a basic module. The 2 × 2 switching matrix (SM) design presented in the manuscript utilizes three input majority gates. Also, the 2 × 2 SM has been proposed using five input majority gates. Two different approaches (1&2) have been presented for designing 2 × 2 SM using five input majority gates. The 2 × 2 SM design based on three input majority gate utilizes four zone clocking scheme to allow signal transmission. Although, the clocking scheme used in 2 × 2 SM using three input MG and in 2 × 2 SM approach 1 using five input MG is conventional. The 2 × 2 SM approach 2 design, utilizes the clocking scheme in which clocks can be applied by electric field generators easily and in turn the switch element becomes physically realizable. The simulation results conclude that the 2 × 2 SM is suitable for designing a 4 × 4 Clos network. A higher order of input-output switching matrix, supporting more number of users can utilize the proposed designs.

Multichannel non-blocking system area network with direct channels

An unblockable non-blocking self-routing network with direct channels has been developed, in which packet conflicts are resolved at the entrance to the network by the procedure of connecting sources to the first cascade of the network , providing a packet duality. Packets blocked during conflict resolution are retransmitted by sources with minimal delays. Within the network, the occurrence of conflicts is prevented by means of parallelization of the network itself. The network is designed in 2-, 4- and 8-stage versions with scaling of the number of channels from several hundred to many millions, keeping the same network performance. The network can provide 1- or 2-channel fault tolerance at the same link rate. The overhead cost of achieving these properties is higher complexity of the network, that becomes comparable to the complexity of the theoretical non-blocking Clos switch, which has no known practical implementation.The purpose of the proposed networks is photonic networks with routing information transmission in packet headers represented as one-time-use binary numbers. The proposed networks are made in an extended circuit basis, consisting of switches and separate multiplexers and demultiplexers. The paper presents the characteristics of the constructed networks with the specified method of presenting routing information.