Reconfigurable Optical Switch Research Articles

Toward tailored light absorption manipulation by Kerr nonlinear nanoslits within a grating Fabry-Perot cavity coupled with reconfigurable GST225 material

In this paper, we investigate the absorption tunability of a silver plasmonic grating incorporating Kerr-type nonlinear graphene-oxide (GO) nanoslits and Ge2Sb2Te5 (GST225) phase-change material at telecom wavelengths. The linear absorption spectra reveal that the amorphous GST225 grating exhibits two distinct absorption peaks, while half-crystallization leads to a single pronounced peak, and full crystallization results in a redshifted peak with a slightly decreased value. These findings confirm that the crystalline degree of GST225 significantly modulates the absorption characteristics. Upon exposure to a nanosecond Gaussian pulse laser irradiation with appropriate fluences, the electric field confinement within the nanoslits intensifies, particularly at the center of the pulse, leading to a pronounced absorption adjustment due to Kerr nonlinearity. Temporal examination at the L-band wavelength of 1591.5 nm reveals a U-shaped absorption response for both amorphous and crystalline GST225, with a pronounced dip at the pulse’s peak. In the half-crystallized state, the weak linear absorption can be substantially enhanced at both the leading and trailing edges of the pulse, with a dip at the center, illustrating the Kerr nonlinearity within the GO nanoslits. The dynamic behavior of absorption under different laser fluences underscores the potential of this system for high-contrast optical switching. Our results offer insights into the development of reconfigurable optical switches utilizing nonlinear Kerr effects, paving the way for advancements in tunable optical communication technologies.

Dynamic capacity sharing with multi-wavelength integrated transmitters in hybrid datacenter networks

In datacenters, bursty and unevenly distributed traffic may lead to serious network performance degradation. Various methods, including reconfigurable optical circuit switching (OCS), traffic control techniques, valiant load balancing (VLB), and so on, have been proposed to solve this problem. Based on these solutions, our method makes a trade-off between cost and performance. In this paper, we propose to use multi-wavelength tunable transmitters in our previously proposed modular arrayed waveguide grating (AWG)-based interconnection network. We discuss how the multiple wavelengths can be shared in the network and then propose a computational model to study its blocking probability. Closed-form equations for low network load cases are also derived to provide the analytical expression for the blocking probability. We verify the accuracy of our computational model through simulations. Comparing the blocking probability of networks with and without multi-wavelength integrated transmitters, we show that network performance can be considerably improved after replacement. When traffic burstiness is 1.25 and traffic skewness is 0.08, the blocking probability is reduced from 0.14 to 3.60×10−3 after replacing in each sending module one fixed laser with multi-wavelength tunable transmitters with four wavelengths. Furthermore, we also discuss how different factors influence the blocking probability and the maximum load with the given network performance requirement.

A Thermally Reconfigurable Photonic Switch Utilizing Drop Cast Vanadium Oxide Nanoparticles on Silicon Waveguides

Photonic switches play a vital role in optical communications and computer networks for establishing and releasing connections of optical signals. With the growing demand for ultra‐compact switches in high‐speed optical computing and communications, thermally reconfigurable optical switches have gained significant attention. These switches offer simplicity, ease of fabrication, and leverage a wide range of thermo‐optic materials. Silicon remains an ideal platform for making photonic devices including the switches due to its compatibility with complementary metal‐oxide‐semiconductor (CMOS) technology and cost‐effectiveness. The article presents a drop cast sub‐stoichiometric vanadium oxide (VO2−x) nanoparticles combined with a silicon ridge waveguide to make a compact thermally reconfigurable optical switch with low transition temperature and accelerated phase transition. Furthermore, the design achieves high modulation depth in addition to its scalability and simplicity. This study demonstrates the potential of solution‐based VO2−x nanoparticles in combination with silicon waveguides for efficient optical switch design for various applications.

Interruptible Scheduling of Partially Re-Configurable Optical Switching in Data Center Networks

Interruptible Scheduling of Partially Re-Configurable Optical Switching in Data Center Networks

Reconfigurable optical logic in silicon platform

In this paper, we present a novel, scalable, and reconfigurable optical switch that performs multiple computational logic functions simultaneously. The free-carrier depletion effect is used to perform non-volatile switching operations due to its high speed and low power consumption. We adopt the concept of optical memory using a phase-change material to realize the non-volatile reconfigurability without a constant power supply, in addition to providing a large operating bandwidth required for reconfigurability. The proposed reconfigurable optical logic architecture is realized in a compact microdisk resonator configuration, utilizing both the carrier-depletion-based modulation and phase-change optical memory. This is the first time these two modulation schemes are implemented in the same optical microdisk for the purpose of reconfigurable optical logic.

Graphene-boosted ultra-wide band reconfigurable optical switch for SOI-based telecom applications: A numerical study

In this work, we propose the design of a compact optical switch featuring a wide bandwidth of 360 nm, suitable for telecom operations. The switch is a passive 3dB splitter realized through a Y-branch, electrically activated via a graphene/insulator/graphene (GIG) capacitor embedded within the rib waveguide (WG). The capacitor itself is embedded within an SOI-based hybrid WG composed of crystalline (c-Si) and hydrogenated amorphous silicon (a-Si:H), with the GIG between the two layers. Such a photonic structure optimizes the light-matter interaction and enables a compact device with a length of only 100 μm. By applying a voltage bias to the graphene layers, we achieve the condition necessary for efficient data transmission through the WG. Indeed, the electrical doping of graphene enables the modulation of optical losses within the waveguide, ranging from total light absorption to up to 70% transmission. The simplicity and ease of fabrication of this innovative design offer significant advantages for integration into existing photonic circuits. Its wide bandwidth allows compatibility with a variety of telecom wavelengths, providing flexibility in network configurations. Consequently, this compact optical switch presents a promising solution for modern data communication needs, demonstrating a balance between efficiency and scalability.

Low-loss Optical Switching Based on Phase-change Material Sb2Se3 in a Micro-ring Resonator

In the past research, optical interconnection has successfully developed into an emerging technology due to its compatibility with CMOS, where an efficient and reconfigurable optical switch operating at ultra-low programming energy is a key element to realize optical signal routing and switching. Here we numerically demonstrate an optical switch operating in the telecommunications band, which shows a 20 dB switch ratio and insertion loss of 0.8 dB. The device is implemented in waveguide-coupled micro-ring resonator (MRR) using the phase materials Sb2Se3, which exhibits high contrast in its optical properties upon transitions between its crystalline and amorphous structural phases.

Electrically switchable metamaterial absorber in visible range based on micro-electro-mechanically system

Spectral control of light in the visible range is one of the fundamental topics in optical applications. Micro-electro-mechanically systems (MEMS) combine with metamaterial structures can further enrich the optical function. Here, a plasmonic metamaterial structures based on MEMS consist of the top metal film and bottom metal slab separated by a dielectric layer was proposed to achieve an electrically switchable metamaterial absorber (MMA). Each metamaterial unit cell is composed of an electrically driven suspended metal film and bottom metal substrate, which can perform independent MEMS functions. Full-wave numerical simulations demonstrated that the shifting of the absorption peaks of the spectrum can be achieved in the visible range. The absorption modulation ratio above 60% can be achieved at wavelengths near 570 nm and 640 nm, provided that the full distance (50 nm) between the top suspended metal film and bottom metal slab can be 100% modulated, which can be easily realized via current MEMS technology. This paves the way for MEMS integrated metamaterial absorber as a platform for reconfigurable optics and optical switching.

RGAIA: a reconfigurable AWGR based optical data center network.

Benefitting from the cost-effective and flexible interconnection between computing nodes and storing infrastructures, various applications and services are deployed in data centers (DCs). These traffic-boosting applications put tremendous pressures on current electrically switched DC networks (DCNs) which suffer the bandwidth bottleneck. Benefitting from the data-rate and format transparency, the optically switched DCN with intrinsic high-bandwidth characteristics is a promising solution to update the hierarchical electrical DCNs with bandwidth limitations. Moreover, the applications deployed in DCNs with mixed traffic characteristics require dynamic quality of service (QoS) provisioning. Optical DCNs thus need to be designed in a flexible topology with the capability of bandwidth reconfigurability to adapt the variety of the traffic. In this paper, we propose and experimentally investigate a reconfigurable optical packet switching DCN named RGAIA, based on flexible top of racks (ToRs) and fast optical switch, where the optical switch is implemented by tunable transceiver combing with arrayed waveguide grating router (AWGR). Under the management of the designed software defined network (SDN) control plane, RGAIA can dynamically distribute the wavelength resource and then reconfigure the bandwidth in real-time based on the monitored traffic characteristics. Experimental assessments validate RGAIA improving performance of 37% and 66% in latency and packet loss, respectively, compared with the network with rigid interconnections at the traffic load of 0.8.

Demonstration of a Hybrid Analog–Digital Transport System Architecture for 5G and Beyond Networks

In future mobile networks, the evolution of optical transport architectures enabling the flexible, scalable interconnection of Baseband Units (BBUs) and Radio Units (RUs) with heterogeneous interfaces is a significant issue. In this paper, we propose a multi-technology hybrid transport architecture that comprises both analog and digital-Radio over Fiber (RoF) mobile network segments relying on a dynamically reconfigurable optical switching node. As a step forward, the integration of the discussed network layout into an existing mobile infrastructure is demonstrated, enabling the support of real-world services through both standard digital and Analog–Intermediate- Frequency over Fiber (A-IFoF)-based converged fiber–wireless paths. Emphasis has been placed on the implementation of a real-time A-IFoF transceiver that is employed through a single embedded fully programmable gateway array (FPGA)-based platform that serves as an Ethernet to Intermediate Frequency (IF) bridge for the transmission of legacy traffic over the analog network segment. The experimental evaluation of the proposed concept was based on the dynamic optical routing of the legacy Common Public Radio Interface (CPRI), 1.5 GBaud analog-intermediate frequency-over-fiber (A-IFoF)/mmWave and 10 Gbps binary optical waveforms, showing acceptable error vector magnitude (EVM) values for the complex radio waveforms and error-free operation for binary optical streams, with Bit Error Rate (BER) values less than 10−9. Finally, the end-to-end proof-of-concept demonstration of the proposed solution was achieved through the delivery of 4K video streaming and Internet Protocol (IP) calls over a mobile core network.

A Universal Method for Constructing N-Port Reconfigurable Non-Blocking Optical Switches on a Silicon Chip

A Universal Method for Constructing <i>N</i>-Port Reconfigurable Non-Blocking Optical Switches on a Silicon Chip

FLEET—Fast Lanes for Expedited Execution at 10 Terabits: Program Overview

The DARPA FastNICs program targets orders of magnitude improvement in applications such as deep learning training by making radical improvements to network performance: While raw bandwidth has grown dramatically, the fundamental roadblock to application performance has been in delivering that data to the application. <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FLEET</small> provides a primarily off-the-shelf solution with high-end servers and shared computational and storage resources connected via PCIe over a reconfigurable MEMS optical switch; it uses custom Optical NICs to allow arbitrary topologies that can be configured before or even during execution to take advantage of shared resources and to flow data between components. <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FLEET</small> 's software is derived from Stanford Legion, which we are modifying to use the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FLEET</small> hardware and to plan application execution for these dynamic network topologies.

Ultrafast reconfigurable nanoscale optical switch based on photonic crystal waveguide

We propose reconfigurable photonic switches with very low input power, ultracompact size, fast response, and low optical loss for high-speed optical network and on-chip interconnect applications. The photonic crystal waveguide-based nanostructure is used to realize the reconfigurable 3 × 3 and 4 × 4 optical switches. The two different operating wavelengths of 1550 and 1630 nm play a significant role in the nanophotonic switching platform. The reconfiguration of optical signal path is effectively attained using these wavelengths with low delay time and high data rate. The performance of nanoswitch parameters is numerically investigated by the finite-difference time-domain method. The proposed optical switch is designed with a low input power of 0.5 mW, fast response time of 607.33 fs, and high data rate of 1.646 Tbps. This high-performance device can be suitable for lightwave communication network, quantum computing, and nanoscale photonic integrated systems.

HoneyComb ROS: A 6 × 6 Non-Blocking Optical Switch with Optimized Reconfiguration for ONoCs

Silicon photonics has become a commonly used paradigm for on-chip interconnects to meet the requirements of higher bandwidth in computationally intensive applications for manycore processors. Design of an optical switch is a vital aspect while constructing an optical NoC topology which influences the performance of network. We present a HoneyComb optimized reconfigurable optical switch (HCROS), a 6 × 6 non-blocking optical switch where optimized reconfiguration of optical links utilizing the states of basic 2 × 2 optical switching elements (OSE) was achieved while keeping the input-output (I/O) interconnection intact. The proposed 6-port HCROS architecture was further optimized to reduce the number of OSEs to minimize overall power consumption. We proposed a generic algorithm to find the optimal switching combination of OSEs for a particular I/O link to minimize the insertion loss and power consumption. In comparison to other non-blocking architectures, a maximum of 66% reduction in OSEs was observed for the optimized HCROS, which consumes only 12 OSEs. Simulations were performed for all 720 I/O links in different configurations to evaluate the power consumption and insertion loss. We observed up to 92% power savings in the case of optimized HCROS as compared to un-optimized HCROS, and a 79% minimization in insertion loss was also reported as a result of optimization.

On the Complexity of Non-Segregated Routing in Reconfigurable Data Center Architectures

By enhancing the traditional static network (e.g., based on electric switches) with a dynamic topology (e.g., based on reconfigurable optical switches), emerging reconfigurable data centers introduce unprecedented flexibilities in how networks can be optimized toward the workload they serve. However, such hybrid data centers are currently limited by a restrictive routing policy enforcing artificial segregation: each network flow can only use either the static or the flexible topology, but not a combination of the two. This paper explores the algorithmic problem of supporting more general routing policies, which are not limited by segregation. While the potential benefits of non-segregated routing have been demonstrated in recent work, the underlying algorithmic complexity is not well-understood. We present a range of novel results on the algorithmic complexity of non-segregated routing. In particular, we show that in certain specific scenarios, optimal data center topologies with nonsegregated routing policies can be computed in polynomial-time. In many variants of the problem, however, introducing a more flexible routing comes at a price of complexity: we prove several important variants to be NP-hard.

A Photonic Switch Based on a Hybrid Combination of Metallic Nanoholes and Phase-change Vanadium Dioxide

A photonic switch is an integral part of optical telecommunication systems. A plasmonic bandpass filter integrated with materials exhibiting phase transition can be used as a thermally reconfigurable optical switch. This paper presents the design and demonstration of a broadband photonic switch based on an aluminium nanohole array on quartz utilising the semiconductor-to-metal phase transition of vanadium dioxide. The fabricated switch shows an operating range over 650 nm around the optical communication C, L, and U band with maximum 20%, 23% and 26% transmission difference in switching in the C band, L band, and U band, respectively. The extinction ratio is around 5 dB in the entire operation range. This architecture is a precursor for developing micron-size photonic switches and ultra-compact modulators for thin film photonics.

Orbital-angular-momentum-based reconfigurable optical switching and routing

Orbital angular momentum (OAM) has gained interest due to its potential to increase capacity in optical communication systems as well as an additional domain for reconfigurable networks. This is due to the following: (i) coaxially propagated OAM beams with different charges are mutually orthogonal, (ii) OAM beams can be efficiently multiplexed and demultiplexed, and (iii) OAM charges can be efficiently manipulated. Therefore, multiple data-carrying OAM beams could have the potential capability for reconfigurable optical switching and routing. In this paper, we discuss work involving reconfigurable OAM-based optical add/drop multiplexing, space switching, polarization switching, channel hopping, and multicasting.

Digital micromirror device as a diffractive reconfigurable optical switch for telecommunication

Digital micromirror devices (DMDs) by their high-switching speed, stability, and repeatability are promising devices for fast, reconfigurable telecommunication switches. However, their binary mirror orientation is an issue for conventional redirection of a large number of incoming ports to a similarly large number of output fibers, like with analog micro-opto electro-mechanical systems. We are presenting here the use of the DMD as a diffraction-based optical switch, where Fourier diffraction patterns are used to steer the incoming beams to any output configuration. Fourier diffraction patterns are computer-generated holograms that structure the incoming light into any shape in the output plane. This way, the light from any fiber can be redirected to any position in the output plane. The incoming light can also be split to any positions in the output plane. This technique has the potential to make an “any-to-any,” true nonblocking, optical switch with high-port count, solving some of the problems of the present technology.

Reconfigurable switching of orbital-angular-momentum-based free-space data channels

Light beams can carry orbital angular momentum (OAM) such that a helical phase front twists along the direction of propagation. OAM beams have been demonstrated in a wide variety of applications and have been found to offer a new orthogonal degree of freedom for multiplexing independent data streams for high-capacity point-to-point optical communications. However, to enable their efficient use in reconfigurable networks, approaches must be developed to manipulate OAM beams. We demonstrate OAM-based reconfigurable optical switching functions among multiple OAM beams. Selective data switching among three 100 Gb/s quadrature phase-shift keying OAM channels was achieved with a 2.1 dB optical signal-to-noise ratio penalty. The scheme of selective OAM-beam manipulation can be potentially cascaded to realize an arbitrary n×n switching function.

An experimental observation of a spatial optical soliton beam and self splitting of beam into two soliton beams in chiral nematic liquid crystal

In this paper, the torque, reorientation and the change in angular momentum of the light are firstly discussed. And moreover, the propagation of light beam (optical spatial soliton beam) at the distance of a few millimeters in chiral nematic liquid crystal (CNLC) will be experimentally under study. In spite of the complex structure of these crystals, due to a self-focusing effect, by injection of infrared laser beam with a power of the order of a few tenths of milliwatts into CNLC an optical spatial soliton beam is observed. In addition, we experimentally obtain the formation of splitting of a soliton beam into two soliton beams which have equal powers due to a saturation of the reorientational nonlinearity. As a matter of fact, this saturation of the reorientational nonlinearity can occur at one point of CNLC, due to the nonlocal nonlinearity. Hence this saturation of the reorientation nonlinearity can split one soliton beam to two soliton beams. This splitting can have a great potential interest for applications in all-optical signal processing, reconfigurable optical interconnects and switching.