Applied Sciences

2022

Jump to: 2021, 2020

34 pages, 45713 KiB

Open AccessArticle

Design and Implementation of Semi-Physical Platform for Label Based Frame Switching in Integrated Satellite Terrestrial Networks

by Wei Zhou, Xing Jiang, Qingsong Luo, Shanguo Huang, Bingli Guo, Xiang Sun, Shaobo Li, Xiaochuan Tan, Mingyi Ma and Tianwen Fu

Appl. Sci. 2022, 12(13), 6674; https://doi.org/10.3390/app12136674 - 1 Jul 2022

Cited by 1 | Viewed by 1985

Abstract

With the explosion of traffic demand in recent years, the integration of satellite optical networks and terrestrial networks (ISTN) creates a promising networking solution for future low-latency, high-rate, and high-capacity communications. Owing to the high cost of deploying and maintaining a satellite optical [...] Read more.

With the explosion of traffic demand in recent years, the integration of satellite optical networks and terrestrial networks (ISTN) creates a promising networking solution for future low-latency, high-rate, and high-capacity communications. Owing to the high cost of deploying and maintaining a satellite optical network, it is critical to carefully design and plan the network to ensure the performance of the network. Thus, a semi-physical simulation platform based on software-defined networks (SDNs) is developed to simulate a satellite optical network and evaluate the performance of the proposed label-based advanced orbiting system (AOS) frame switching method that adheres to the Consultative Committee for Space Data Systems’ recommended standard (CCSDS). The semi-physical simulation platform has two major innovations: (1) adapting and integrating network protocols between the CCSDS and open system interconnect (OSI) reference models, particularly at the data link layer, and (2) the foundation for an SDN-based satellite optical network. In the control plane, real-time VxWorks Simulators serve as controllers to establish and manage various network protocols and the link manager protocol (LMP). Here, network protocols include open shortest path first (OSPF) for routing managing and controlling messages, constraint shortest path first–traffic engineering (CSPF-TE), and constraint-label distribution protocol (CR-LDP) for routing data services. LMP is used to assign and reserve satellite optical link resources. The performance of the architecture and protocols is evaluated via a semi-physical simulation platform. Full article

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14 pages, 2227 KiB

Open AccessEditor’s ChoiceReview

A Review of Optical Neural Networks

by Danni Zhang and Zhongwei Tan

Appl. Sci. 2022, 12(11), 5338; https://doi.org/10.3390/app12115338 - 25 May 2022

Cited by 16 | Viewed by 11331

Abstract

With the continuous miniaturization of conventional integrated circuits, obstacles such as excessive cost, increased resistance to electronic motion, and increased energy consumption are gradually slowing down the development of electrical computing and constraining the application of deep learning. Optical neuromorphic computing presents various [...] Read more.

With the continuous miniaturization of conventional integrated circuits, obstacles such as excessive cost, increased resistance to electronic motion, and increased energy consumption are gradually slowing down the development of electrical computing and constraining the application of deep learning. Optical neuromorphic computing presents various opportunities and challenges compared with the realm of electronics. Algorithms running on optical hardware have the potential to meet the growing computational demands of deep learning and artificial intelligence. Here, we review the development of optical neural networks and compare various research proposals. We focus on fiber-based neural networks. Finally, we describe some new research directions and challenges. Full article

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22 pages, 13042 KiB

Open AccessArticle

Evolution of System Embedded Optical Interconnect in Sub-Top-of-Rack Data Center Systems

by Richard Pitwon, Anil Reddy, Aditya Jain, Kevin Gomez, Sebastian A. Schulz, Liam O’Faolain, Kai Wang, Allen Miller and Vivienne Davies

Appl. Sci. 2022, 12(3), 1565; https://doi.org/10.3390/app12031565 - 31 Jan 2022

Cited by 3 | Viewed by 5653

Abstract

In this paper we review key technological milestones in system embedded optical interconnects in data centers that have been achieved between 2014 and 2020 on major European Union research and development projects. This includes the development of proprietary optically enabled data storage and [...] Read more.

In this paper we review key technological milestones in system embedded optical interconnects in data centers that have been achieved between 2014 and 2020 on major European Union research and development projects. This includes the development of proprietary optically enabled data storage and switch systems and optically enabled data storage and compute subsystems. We report on four optically enabled data center system demonstrators: LightningValley, ThunderValley2, Pegasus and Aurora, which include advanced optical circuits based on polymer waveguides and fibers and proprietary electro-optical connectors. We also report on optically enabled subsystems including Ethernet-connected hard disk drives and microservers. Both are designed in the same pluggable carrier form factor and with embedded optical transceiver and connector interfaces, thus allowing, for the first time, both compute and storage nodes to be optically interchangeable and directly interconnectable over long distances. Finally, we present the Nexus platform, which allows different optically enabled data center test systems and subsystems to be interconnected and comparatively characterized within a data center test environment. Full article

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30 pages, 3161 KiB

Open AccessArticle

Multiple-Valued Logic Modelling for Agents Controlled via Optical Networks

by Alexey Yu. Bykovsky

Appl. Sci. 2022, 12(3), 1263; https://doi.org/10.3390/app12031263 - 25 Jan 2022

Cited by 6 | Viewed by 2504

Abstract

The methods of data verification are discussed, which are intended for the distant control of autonomous mobile robotic agents via networks, combining optical data links. The problem of trust servers is considered for position verification and position-based cryptography tasks. In order to obtain [...] Read more.

The methods of data verification are discussed, which are intended for the distant control of autonomous mobile robotic agents via networks, combining optical data links. The problem of trust servers is considered for position verification and position-based cryptography tasks. In order to obtain flexible quantum and classical verification procedures, one should use the collective interaction of agents and network nodes, including some elements of the blockchain. Multiple-valued logic functions defined within discrete k-valued Allen–Givone algebra are proposed for the logically linked list of entries and the distributed ledger, which can be used for distant data verification and breakdown restoration in mobile agents with the help of partner network nodes. A distributed ledger scheme involves the assigning by distant partners of random hash values, which further can be used as keys for access to a set of distributed data storages, containing verification and restoration data. Multiple-valued logic procedures are simple and clear enough for high-dimensional logic modelling and for the design of combined quantum and classical protocols. Full article

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14 pages, 3038 KiB

Open AccessArticle

Planning of Optical Connections in 5G Packet-Optical xHaul Access Network

by Mirosław Klinkowski and Marek Jaworski

Appl. Sci. 2022, 12(3), 1146; https://doi.org/10.3390/app12031146 - 22 Jan 2022

Cited by 6 | Viewed by 2529

Abstract

One of the main challenges in dense 5G radio access networks (RANs) is provisioning of low-cost connectivity between a large number of antennas, located at remote sites, and a central site (hub) in which baseband processing functions are performed. Packet-switched Ethernet and wavelength [...] Read more.

One of the main challenges in dense 5G radio access networks (RANs) is provisioning of low-cost connectivity between a large number of antennas, located at remote sites, and a central site (hub) in which baseband processing functions are performed. Packet-switched Ethernet and wavelength division multiplexing (WDM) are two principal transport network technologies enabling the reduction of the demand for direct optical fiber connections between the antennas and the hub. Whereas Ethernet allows for statistical multiplexing of multiple xHaul (fronthaul/midhaul/backhaul) flows and their aggregation in a high-capacity transmission link, WDM makes it possible to establish a number of such links (using different wavelengths) in a single optical fiber. Additional savings in the amount of fibers required can be achieved by means of optical add-drop multiplexers (OADMs) that allow for obtaining access to unused wavelengths by intermediate remote nodes, whenever the capacity on the WDM system is not fully utilized by the end remote node. In this work, we focus on the problem of planning optimal fiber connections, including the placement of OADMs for a set of wavelength demands at remote sites, with the aim of minimizing the amount of fibers used in a packet-optical xHaul access network carrying 5G traffic. We consider a passive WDM system in which the maximum transmission distance, estimated using an optical power-budget model, depends on the number of OADMs that are present on the transmission path. To formulate and solve the optimization problem, we make use of integer linear programming (ILP). We apply the ILP model in network analysis. In particular, by means of numerical experiments performed for two different network topologies, we study the impact of traffic load (in terms of the number of requested wavelengths) and optical multiplexer loss on the number of transmission paths that have to be established in the network. Obtained results show that the savings in fiber connections of up to

65 %

can be achieved in a packet-optical xHaul network if OADMs are used when compared to the scenario without OADMs. Full article

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2021

Jump to: 2022, 2020

16 pages, 6783 KiB

Open AccessArticle

Silicon Photonic Micro-Transceivers for Beyond 5G Environments

by Kazuhiko Kurata, Luca Giorgi, Fabio Cavaliere, Liam O’Faolain, Sebastian A. Schulz, Kohei Nishiyama, Yasuhiko Hagihara, Kenichiro Yashiki, Takashi Muto, Shigeru Kobayashi, Makoto Kuwata and Richard Pitwon

Appl. Sci. 2021, 11(22), 10955; https://doi.org/10.3390/app112210955 - 19 Nov 2021

Cited by 5 | Viewed by 4842

Abstract

Here, we report on the design and performance of a silicon photonic micro-transceiver required to operate in 5G and 6G environments at high ambient temperatures above 105 °C. The four-channel “IOCore” micro-transceiver incorporates a 1310 nm quantum dot laser system and operates at [...] Read more.

Here, we report on the design and performance of a silicon photonic micro-transceiver required to operate in 5G and 6G environments at high ambient temperatures above 105 °C. The four-channel “IOCore” micro-transceiver incorporates a 1310 nm quantum dot laser system and operates at a data rate of 25 Gbps and higher. The 5 × 5 mm micro-transceiver chip benefits from a multimode coupling interface for low-cost assembly and robust connectivity at high temperatures as well as an optical redundancy scheme, which increases reliability by over an order of magnitude. Full article

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16 pages, 5069 KiB

Open AccessArticle

Packet Optical Transport Network Slicing with Hard and Soft Isolation

by Samier Barguil, Victor Lopez Alvarez, Luis Miguel Contreras Murillo, Oscar Gonzalez de Dios, Alejandro Alcala Alvarez, Carlos Manso, Pol Alemany, Ramon Casellas, Ricardo Martinez, David Gonzalez-Perez, Xufeng Liu, Jose-Miguel Pulido, Juan Pedro Fernandez-Palacios, Raul Muñoz and Ricard Vilalta

Appl. Sci. 2021, 11(13), 6219; https://doi.org/10.3390/app11136219 - 5 Jul 2021

Cited by 4 | Viewed by 3549

Abstract

Network operators have been dealing with the necessity of a dynamic network resources allocation to provide a new generation of customer-tailored applications. In that sense, Telecom providers have to migrate their BSS/OSS systems and network infrastructure to more modern solutions to introduce end-to-end [...] Read more.

Network operators have been dealing with the necessity of a dynamic network resources allocation to provide a new generation of customer-tailored applications. In that sense, Telecom providers have to migrate their BSS/OSS systems and network infrastructure to more modern solutions to introduce end-to-end automation and support the new use cases derived from the 5G adoption and transport network slices. In general, there is a joint agreement on making this transition to an architecture defined by programmable interfaces and standard protocols. Hence, this paper uses the iFusion architecture to control and program the network infrastructure. The work presents an experimental validation of the network slicing instantiation in an IP/Optical environment using a set of standard protocols and interfaces. The work provides results of the creation, modification and deletion of the network slices. Furthermore, it demonstrates the usage of standard communication protocols (Netconf and Restconf) in combination with standard YANG data models. Full article

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15 pages, 2922 KiB

Open AccessArticle

Integrating Optical and Wireless Techniques towards Novel Fronthaul and Access Architectures in a 5G NR Framework

by Ramon Maia Borges, Celso Henrique de Souza Lopes, Eduardo Saia Lima, Marco Aurélio de Oliveira, Matheus Sêda Borsato Cunha, Luciano Camilo Alexandre, Luis Gustavo da Silva, Luiz Augusto Melo Pereira, Danilo Henrique Spadoti, Murilo Araujo Romero and Arismar Cerqueira Sodré Junior

Appl. Sci. 2021, 11(11), 5048; https://doi.org/10.3390/app11115048 - 29 May 2021

Cited by 14 | Viewed by 4300

Abstract

The fifth-generation of mobile network (5G) and beyond requires a radio access network (RAN) update in order to cope with the incoming increase of wireless data traffic and new applications. In this context, we propose an efficient optical-wireless architecture applied to the non-standalone [...] Read more.

The fifth-generation of mobile network (5G) and beyond requires a radio access network (RAN) update in order to cope with the incoming increase of wireless data traffic and new applications. In this context, we propose an efficient optical-wireless architecture applied to the non-standalone (NSA) 5G new radio (NR) framework. Several distinct electrical- and optical-based fronthaul configurations combining free-space optical (FSO), wireless links, and radio over fiber (RoF) techniques were implemented and properly analyzed for selection according to network operator deployment requirements. In addition, visible light communication (VLC) was investigated as a future access network technology when immunity to electromagnetic interference is paramount. Experimental results demonstrated fourth-generation of mobile network (4G) and 5G coexistence at Gbit/s throughput and error vector magnitude (EVM) in accordance with 5G NR Release 15. Full article

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10 pages, 1448 KiB

Open AccessArticle

A Programmable ROADM System for SDM/WDM Networks

by Ruizhi Yang, Lida Liu, Shuangyi Yan and Dimitra Simeonidou

Appl. Sci. 2021, 11(9), 4195; https://doi.org/10.3390/app11094195 - 5 May 2021

Cited by 6 | Viewed by 3051

Abstract

This paper proposed and evaluated a programmable ROADM system for MCF-based SDM/WDM networks. The proposed ROADM system employing both bypass connection and Route-and-Select wavelength switching enables adaptable virtual topology in optical networks by dynamically configuring bypass connection cores. The simulation results confirmed this [...] Read more.

This paper proposed and evaluated a programmable ROADM system for MCF-based SDM/WDM networks. The proposed ROADM system employing both bypass connection and Route-and-Select wavelength switching enables adaptable virtual topology in optical networks by dynamically configuring bypass connection cores. The simulation results confirmed this ROADM system could provide acceptable performance with an around 10–20% reduction in the total cost including the number of ports and WSSs by comparing with a fully flexible SDM/WDM ROADM system, which cannot be implemented due to the required extremely high-port-count WSSs. Full article

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13 pages, 1731 KiB

Open AccessArticle

Multi-Tier Heterogeneous Beam Management for Future Indoor FSO Networks

by Michael B. Rahaim, Thomas D. C. Little and Mona Hella

Appl. Sci. 2021, 11(8), 3627; https://doi.org/10.3390/app11083627 - 17 Apr 2021

Cited by 2 | Viewed by 3338

Abstract

To meet the growing demand for wireless capacity, communications in the Terahertz (THz) and optical bands are being broadly explored. Communications within these bands provide massive bandwidth potential along with highly directional beam steering capabilities. While the available bandwidth offers incredible link capacity, [...] Read more.

To meet the growing demand for wireless capacity, communications in the Terahertz (THz) and optical bands are being broadly explored. Communications within these bands provide massive bandwidth potential along with highly directional beam steering capabilities. While the available bandwidth offers incredible link capacity, the directionality of these technologies offers an even more significant potential for spatial capacity or area spectral efficiency. However, this directionality also implies a challenge related to the network’s ability to quickly establish a connection. In this paper, we introduce a multi-tier heterogeneous (MTH) beamform management strategy that utilizes various wireless technologies in order to quickly acquire a highly directional indoor free space optical communication (FSO) link. The multi-tier design offers the high resolution of indoor FSO while the millimeter-wave (mmWave) system narrows the FSO search space. By narrowing the search space, the system relaxes the requirements of the FSO network in order to assure a practical search time. This paper introduces the necessary components of the proposed beam management strategy and provides a foundational analysis framework to demonstrate the relative impact of coverage, resolution, and steering velocity across tiers. Furthermore, an optimization analysis is used to define the top tier resolution that minimizes worst-case search time as a function of lower tier resolution and top tier range. Full article

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10 pages, 3147 KiB

Open AccessFeature PaperArticle

Low Complexity DSP for High Speed Optical Access Networking

by Jinlong Wei, Cedric F. Lam, Ji Zhou, Ivan Aldaya, Elias Giacoumidis, Andre Richter, Qixiang Cheng, Richard Penty and Ian White

Appl. Sci. 2021, 11(8), 3406; https://doi.org/10.3390/app11083406 - 10 Apr 2021

Viewed by 2873

Abstract

A novel low-cost and energy-efficient approach for reaching 40 Gb/s signals is proposed for cost-sensitive optical access networks. Our proposed design is constituted of an innovative low-complex high-performance digital signal processing (DSP) architecture for pulse amplitude modulation (PAM-4), reuses existing commercial cost-effective 10-G [...] Read more.

A novel low-cost and energy-efficient approach for reaching 40 Gb/s signals is proposed for cost-sensitive optical access networks. Our proposed design is constituted of an innovative low-complex high-performance digital signal processing (DSP) architecture for pulse amplitude modulation (PAM-4), reuses existing commercial cost-effective 10-G components and eliminates the need of a power-hungry radio frequency (RF) component in the transmitter. Using a multi-functional 17-tap reconfigurable adaptive Volterra-based nonlinear equalizer with noise suppression, significant improvement in receiver optical power sensitivity is achieved. Results show that over 30 km of single-mode fiber (SMF) a link power budget of 33 dB is feasible at a bit-error-rate (BER) threshold of 10⁻³. Full article

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14 pages, 7201 KiB

Open AccessFeature PaperArticle

Emulating Software-Defined Disaggregated Optical Networks in a Containerized Framework

by Francisco-Javier Moreno-Muro, Miquel Garrich, Ignacio Iglesias-Castreño, Safaa Zahir and Pablo Pavón-Mariño

Appl. Sci. 2021, 11(5), 2081; https://doi.org/10.3390/app11052081 - 26 Feb 2021

Cited by 7 | Viewed by 2716

Abstract

Telecom operators’ infrastructure is undergoing high pressure to keep the pace with the traffic demand generated by the societal need of remote communications, bandwidth-hungry applications, and the fulfilment of 5G requirements. Software-defined networking (SDN) entered in scene decoupling the data-plane forwarding actions from [...] Read more.

Telecom operators’ infrastructure is undergoing high pressure to keep the pace with the traffic demand generated by the societal need of remote communications, bandwidth-hungry applications, and the fulfilment of 5G requirements. Software-defined networking (SDN) entered in scene decoupling the data-plane forwarding actions from the control-plane decisions, hence boosting network programmability and innovation. Optical networks are also capitalizing on SDN benefits jointly with a disaggregation trend that holds the promise of overcoming traditional vendor-locked island limitations. In this work, we present our framework for disaggregated optical networks that leverages on SDN and container-based management for a realistic emulation of deployment scenarios. Our proposal relies on Kubernetes for the containers’ control and management, while employing the NETCONF protocol for the interaction with the light-weight software entities, i.e., agents, which govern the emulated optical devices. Remarkably, our agents’ structure relies on components that offer high versatility for accommodating the wide variety of components and systems in the optical domain. We showcase our proposal with the emulation of an 18-node European topology employing Cassini-compliant optical models, i.e., a state-of-the-art optical transponder proposed in the Telecom Infrastructure Project. The combination of our versatile framework based on containerized entities, the automatic creation of agents and the optical-layer characteristics represents a novel approach suitable for operationally complex carrier-grade transport infrastructure with SDN-based disaggregated optical systems. Full article

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10 pages, 824 KiB

Open AccessArticle

Analyses of the Key Technologies and Development Trends of Optical Networks from the Perspective of Standard Essential Patents

by Shu-Hao Chang

Appl. Sci. 2021, 11(4), 1583; https://doi.org/10.3390/app11041583 - 10 Feb 2021

Cited by 6 | Viewed by 2565

Abstract

Because of the advancement of 5G, mobile devices, and broadband, the development of optical network technologies has received increased research attention. However, studies have mostly focused on the technical or market aspects rather than employing a macroscopic perspective to reveal the technology distribution [...] Read more.

Because of the advancement of 5G, mobile devices, and broadband, the development of optical network technologies has received increased research attention. However, studies have mostly focused on the technical or market aspects rather than employing a macroscopic perspective to reveal the technology distribution of optical networks and the development trends in their key fields. Given that technologies disclosed by standard essential patents (SEPs) are the key technologies that determine the standards in relevant industries, we used SEPs optical networks as the basis of analyses and constructed a technology network. Therefore, the contribution of this study lies in bridging the research gap between two studies, using the perspective of SEPs to observe the key technologies in leading industry standard-setting. In addition to the aspects of technologies and markets addressed in existing studies, this study primarily discusses technology distribution and trends in optical networks. The results reveal that transmission of digital information, wireless communication networks and multiple communication are the key technical fields in developing optical networks, with wireless communication devices and digital information transmission being the main focus in recent years. Considering the gradual standardization of future optical network technologies and the fierce competition between manufacturers in SEP applications, relevant industries and universities should cooperate in key technical fields for research and development as well as in talent cultivation to facilitate the development of key technologies and industrial standards in optical networks. The current results may serve as a reference for both industry and academia with regard to research and development resource allocation. Full article

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21 pages, 4879 KiB

Open AccessFeature PaperReview

Optical Technology for NFV Converged Networks

by Paola Iovanna, Alessandra Bigongiari, Alberto Bianchi, Sylvie Menezo, Marco Romagnoli, Vito Sorianello and Fabio Cavaliere

Appl. Sci. 2021, 11(4), 1522; https://doi.org/10.3390/app11041522 - 8 Feb 2021

Cited by 4 | Viewed by 2998

Abstract

5G and its evolution towards 6G is unlocking new use cases that will require the reconsideration of the existing network architectures and its operation. As the network will be required to support new service types and radio protocol splits, the traditional physical point [...] Read more.

5G and its evolution towards 6G is unlocking new use cases that will require the reconsideration of the existing network architectures and its operation. As the network will be required to support new service types and radio protocol splits, the traditional physical point to point connections will need to be replaced with a transport network up to the antenna site to guarantee low latency services and high bandwidth. Optical based transport is a key enabler to realize such a convergent network, where the traditional fixed infrastructure in use for mobile services and mobile infrastructure should also support enterprises services. The Software Defined Network (SDN) and Network Function Virtualization (NFV) technology plays a key role to evolve towards digitalization. It allows to simplify the creation of new services and to implement a real decoupling between the infrastructure and the network functions that run virtually, on generic processing units located everywhere in the network. Supporting automation is a key requirement that traditional optical technology is not able to meet. In this paper the reference scenarios for the access network are presented with the analysis of their requirements and the enabling optical solutions based on integrated silicon photonics. Full article

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17 pages, 4597 KiB

Open AccessArticle

An Experimental OpenFlow Proposal over Legacy GPONs to Allow Real-Time Service Reconfiguration Policies

by Noemí Merayo, David de Pintos, Juan C. Aguado, Ignacio de Miguel, Ramón J. Durán, Patricia Fernández, Rubén M. Lorenzo and Evaristo J. Abril

Appl. Sci. 2021, 11(3), 903; https://doi.org/10.3390/app11030903 - 20 Jan 2021

Cited by 4 | Viewed by 2552

Abstract

The integration of Software Defined Networking (SDN) technologies in Passive Optical Networks (PONs) would provide great advantages to Internet Service Providers (ISPs) and Network Operators, since they can optimize the network operation and reduce its complexity. However, some tasks regarding online service and [...] Read more.

The integration of Software Defined Networking (SDN) technologies in Passive Optical Networks (PONs) would provide great advantages to Internet Service Providers (ISPs) and Network Operators, since they can optimize the network operation and reduce its complexity. However, some tasks regarding online service and network configuration strategies are difficult to move to external SDN-controllers since they are time-critical operations. However, the control of some of these policies by SDN techniques could lead to better network and management configuration in a centralized and automatic way. As a consequence, we propose and experimentally test the integration of an OpenFlow approach over legacy Gigabit Passive Optical Networks (GPONs), which allows moving some global service configuration policies to an external SDN controller implementing an SDN management layer that adjust these strategies according to dynamic Quality of Service (QoS) requirements of services in residential users. The viability and efficiency of our approach are demonstrated using a GPON testbed and proposing a new business scenario for ISPs and Network Operators. Full article

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2020

Jump to: 2022, 2021

9 pages, 1077 KiB

Open AccessLetter

Rearrangeable Nonblocking Conditions for Four Elastic Optical Data Center Networks

by Bey-Chi Lin

Appl. Sci. 2020, 10(21), 7428; https://doi.org/10.3390/app10217428 - 22 Oct 2020

Cited by 3 | Viewed by 1657

Abstract

Four variants of elastic optical data center network (DCN) architectures based on optical circuit switching were proposed in an earlier study. The necessary and sufficient values of frequency slot units (FSUs) per fiber required for these four DCNs in the sense of there [...] Read more.

Four variants of elastic optical data center network (DCN) architectures based on optical circuit switching were proposed in an earlier study. The necessary and sufficient values of frequency slot units (FSUs) per fiber required for these four DCNs in the sense of there being strictly nonblocking (SNB) were derived, but no results in the sense of being rearrangeable nonblocking (RNB) were presented. In reality, only limited bandwidths are available, and reducing the value of FSUs per fiber has become a critical task to realize nonblocking optical DCN architectures in practice. In this paper, we derive the sufficient value of FSUs per fiber required for the four DCNs to be RNB by two multigraph approaches. Our results show that the proposed RNB conditions in terms of FSUs per fiber for a certain two of the four DCNs reduce their SNB results down to at least half for most cases, and even down to one-third. Full article

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8 pages, 3150 KiB

Open AccessArticle

Low-Loss and Broadband Silicon Photonic 3-dB Power Splitter with Enhanced Coupling of Shallow-Etched Rib Waveguides

by Vinh Huu Nguyen, In Ki Kim and Tae Joon Seok

Appl. Sci. 2020, 10(13), 4507; https://doi.org/10.3390/app10134507 - 29 Jun 2020

Cited by 21 | Viewed by 5115

Abstract

A silicon photonic 3-dB power splitter is one of the essential components to demonstrate large-scale silicon photonic integrated circuits (PICs), and can be utilized to implement modulators, 1 × 2 switches, and 1 × N power splitters for various PIC applications. In this [...] Read more.

A silicon photonic 3-dB power splitter is one of the essential components to demonstrate large-scale silicon photonic integrated circuits (PICs), and can be utilized to implement modulators, 1 × 2 switches, and 1 × N power splitters for various PIC applications. In this paper, we reported the design and experimental demonstration of low-loss and broadband silicon photonic 3-dB power splitters. The power splitter was realized by adiabatically tapered rib waveguides with 60-nm shallow etches. The shallow-etched rib waveguides offered strong coupling and relaxed critical dimensions (a taper tip width of 200 nm and gap spacing of 300 nm). The fabricated device exhibited an excess loss as low as 0.06 dB at a 1550-nm wavelength and a broad operating wavelength range from 1470 nm to 1570 nm. The relaxed critical dimensions (≥200 nm) make the power splitter compatible with standard fabrication processes of existing silicon photonics foundries. Full article

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