シリコンフォトニクスを用いた高速・高感度光受信器に関する研究

Tohoku University山田　博仁課

Optical coupling for multi-layer printed wiring board by selfwritten waveguide

For the future of optical interconnect, high optical coupling efficiency is required for high density multilayer optical printed wiring board (OPWB). Hence, we propose optical pin as optical coupling devices between surface devices and the multi-layer channel of OPWB using self-written waveguide (SWW) with mask-transfer method. SWW-pin is passively aligned and mask-transfer provides precise positioning between surface device and channel waveguide. This makes these technology is a promising technology for coupling device. A comparison of coupling efficiency of three cases methods is performed-using ray-tracing simulation. The calculation for optical coupling efficiency with vertical pin of -0.05 dB is achieved. The proposed of an easy and sufficient fabrication concept using MTSW method with the application of prism are expected. The vertical pin technologies are anticipated to be useful in the future of high optical coupling devices of the multi-layer and multi-channel waveguides and /or a multi-core optical fiber

Development of multi-element fibres for applications in space-division multiplexing

This thesis presents a novel multi-element fibre (MEF) technology for implementing space-division multiplexing (SDM) in optical fibres. MEF comprises multiple fibre-elements that are drawn and coated together using a common polymer coating. In MEF, the fibre-elements are compatible with current technology i. e. the fibre-elements can be directly fusion spliced to standard single mode pigtail fibre. Thus, a smooth upgrade from WDM based systems to SDM system is possible. In this work, MEF technology has been implemented for both, passive SDM fibres and SDM amplifiers.Erbium-doped Core-pump MEF amplifiers have been demonstrated exhibiting similar gain and noise figure performance to conventional Er-doped fibre amplifier while maintaining ultralow crosstalk levels. In addition, an Erbium/Ytterbium-doped cladding-pumped MEF amplifier has been developed, and a novel technique to achieve a broadband gain has been demonstrated which could cover wavelength region of 1536nm-1615nm using a single multimode pump. Furthermore, MEF technology has been combined with mode-division multiplexing to show that higher spatial multiplicity could be achieved by implementing the MEF with other SDM technologies.In passive MEFs, the fabricated fibres have been characterised for their loss and transmission properties, showing low loss and error-free transmission. Also, the MEFs are proof-tested showing high strength. The compatibility of MEF fibres have been tested in a concatenated SDM system demonstrating their flexibility in the telecom network

Next Generation Silicon Photonic Transceiver: From Device Innovation to System Analysis

Silicon photonics is recognized as a disruptive technology that has the potential to reshape many application areas, for example, data center communication, telecommunications, high-performance computing, and sensing. The key capability that silicon photonics offers is to leverage CMOS-style design, fabrication, and test infrastructure to build compact, energy-efficient, and high-performance integrated photonic systems-on- chip at low cost. As the need to squeeze more data into a given bandwidth and a given footprint increases, silicon photonics becomes more and more promising. This work develops and demonstrates novel devices, methodologies, and architectures to resolve the challenges facing the next-generation silicon photonic transceivers. The first part of this thesis focuses on the topology optimization of passive silicon photonic devices. Specifically, a novel device optimization methodology - particle swarm optimization in conjunction with 3D finite-difference time-domain (FDTD), has been proposed and proven to be an effective way to design a wide range of passive silicon photonic devices. We demonstrate a polarization rotator and a 90◦ optical hybrid for polarization-diversity and phase-diversity communications - two important schemes to increase the communication capacity by increasing the spectral efficiency. The second part of this thesis focuses on the design and characterization of the next- generation silicon photonic transceivers. We demonstrate a polarization-insensitive WDM receiver with an aggregate data rate of 160 Gb/s. This receiver adopts a novel architecture which effectively reduces the polarization-dependent loss. In addition, we demonstrate a III-V/silicon hybrid external cavity laser with a tuning range larger than 60 nm in the C-band on a silicon-on-insulator platform. A III-V semiconductor gain chip is hybridized into the silicon chip by edge-coupling to the silicon chip. The demonstrated packaging method requires only passive alignment and is thus suitable for high-volume production. We also demonstrate all silicon-photonics-based transmission of 34 Gbaud (272 Gb/s) dual-polarization 16-QAM using our integrated laser and silicon photonic coherent transceiver. The results show no additional penalty compared to commercially available narrow linewidth tunable lasers. The last part of this thesis focuses on the chip-scale optical interconnect and presents two different types of reconfigurable memory interconnects for multi-core many-memory computing systems. These reconfigurable interconnects can effectively alleviate the memory access issues, such as non-uniform memory access, and Network-on-Chip (NoC) hot-spots that plague the many-memory computing systems by dynamically directing the available memory bandwidth to the required memory interface

Advanced DSP Techniques for High-Capacity and Energy-Efficient Optical Fiber Communications

The rapid proliferation of the Internet has been driving communication networks closer and closer to their limits, while available bandwidth is disappearing due to an ever-increasing network load. Over the past decade, optical fiber communication technology has increased per fiber data rate from 10 Tb/s to exceeding 10 Pb/s. The major explosion came after the maturity of coherent detection and advanced digital signal processing (DSP). DSP has played a critical role in accommodating channel impairments mitigation, enabling advanced modulation formats for spectral efficiency transmission and realizing flexible bandwidth. This book aims to explore novel, advanced DSP techniques to enable multi-Tb/s/channel optical transmission to address pressing bandwidth and power-efficiency demands. It provides state-of-the-art advances and future perspectives of DSP as well

Optical Wireless Data Center Networks

Bandwidth and computation-intensive Big Data applications in disciplines like social media, bio- and nano-informatics, Internet-of-Things (IoT), and real-time analytics, are pushing existing access and core (backbone) networks as well as Data Center Networks (DCNs) to their limits. Next generation DCNs must support continuously increasing network traffic while satisfying minimum performance requirements of latency, reliability, flexibility and scalability. Therefore, a larger number of cables (i.e., copper-cables and fiber optics) may be required in conventional wired DCNs. In addition to limiting the possible topologies, large number of cables may result into design and development problems related to wire ducting and maintenance, heat dissipation, and power consumption. To address the cabling complexity in wired DCNs, we propose OWCells, a class of optical wireless cellular data center network architectures in which fixed line of sight (LOS) optical wireless communication (OWC) links are used to connect the racks arranged in regular polygonal topologies. We present the OWCell DCN architecture, develop its theoretical underpinnings, and investigate routing protocols and OWC transceiver design. To realize a fully wireless DCN, servers in racks must also be connected using OWC links. There is, however, a difficulty of connecting multiple adjacent network components, such as servers in a rack, using point-to-point LOS links. To overcome this problem, we propose and validate the feasibility of an FSO-Bus to connect multiple adjacent network components using NLOS point-to-point OWC links. Finally, to complete the design of the OWC transceiver, we develop a new class of strictly and rearrangeably non-blocking multicast optical switches in which multicast is performed efficiently at the physical optical (lower) layer rather than upper layers (e.g., application layer). Advisors: Jitender S. Deogun and Dennis R. Alexande

Enabling Technology in Optical Fiber Communications: From Device, System to Networking

This book explores the enabling technology in optical fiber communications. It focuses on the state-of-the-art advances from fundamental theories, devices, and subsystems to networking applications as well as future perspectives of optical fiber communications. The topics cover include integrated photonics, fiber optics, fiber and free-space optical communications, and optical networking

Mapping multiplexing technique (MMT): a novel intensity modulated transmission format for high-speed optical communication systems

There is a huge rapid growth in the deployment of data centers, mainly driven from the increasing demand of internet services as video streaming, e-commerce, Internet Of Things (IOT), social media, and cloud computing. This led data centers to experience an expeditious increase in the amount of network traffic that they have to sustain due to requirement of scaling with the processing speed of Complementary metal–oxide–semiconductor (CMOS) technology. On the other side, as more and more data centers and processing cores are on demand, as the power consumption is becoming a challenging issue. Unless novel power efficient methodologies are innovated, the information technology industry will be more liable to a future power crunch. As such, low complex novel transmission formats featuring both power efficiency and low cost are considered the major characteristics enabling large-scale, high performance data transmission environment for short-haul optical interconnects and metropolitan range data networks. In this thesis, a novel high-speed Intensity-Modulated Direct-Detection (IM/DD) transmission format named “Mapping Multiplexing Technique (MMT)” for high-speed optical fiber networks, is proposed and presented. Conceptually, MMT design challenges the high power consumption issue that exists in high-speed short and medium range networks. The proposed novel scheme provides low complex means for increasing the power efficiency of optical transceivers at an impactful tradeoff between power efficiency, spectral efficiency, and cost. The novel scheme has been registered as a patent (Malaysia PI2012700631) that can be employed for applications related but not limited to, short-haul optical interconnects in data centers and Metropolitan Area networks (MAN). A comprehensive mathematical model for N-channel MMT modulation format has been developed. In addition, a signal space model for the N-channel MMT has been presented to serve as a platform for comparison with other transmission formats under optical channel constraints. Especially, comparison with M-PAM, as meanwhile are of practical interest to expand the capacity for optical interconnects deployment which has been recently standardized for Ethernet IEEE 802.3bs 100Gb/s and in today ongoing investigation activities by IEEE 802.3 400Gb/s Ethernet Task Force. Performance metrics have been considered by the derivation of the average electrical and optical power for N-channel MMT symbols in comparison with Pulse Amplitude Modulation (M-PAM) format with respect to the information capacity. Asymptotic power efficiency evaluation in multi-dimensional signal space has been considered. For information capacity of 2, 3 and 4 bits/symbol, 2-channel, 3-channel and 4-channel MMT modulation formats can reduce the power penalty by 1.76 dB, 2.2 dB and 4 dB compared with 4-PAM, 8-PAM and 16-PAM, respectively. This enhancement is equivalent to 53%, 60% and 71% energy per bit reduction to the transmission of 2, 3 and 4 bits per symbol employing 2-, 3- and 4-channel MMT compared with 4-, 8- and 16-PAM format, respectively. One of the major dependable parameters that affect the immunity of a modulation format to fiber non-linearities, is the system baud rate. The propagation of pulses in fiber with bitrates in the order > 10G, is not only limited by the linear fiber impairments, however, it has strong proportionality with fiber intra-channel non-linearities (Self Phase Modulation (SPM), Intra-channel Cross-Phase Modulation (IXPM) and Intra-channel Four-Wave Mixing (IFWM)). Hence, in addition to the potential application of MMT in short-haul networks, the thesis validates the practicality of implementing N-channel MMT system accompanied by dispersion compensation methodologies to extend the reach of error free transmission (BER ≤ 10-12) for Metro-networks. N-Channel MMT has been validated by real environment simulation results to outperform the performance of M-PAM in tolerating fiber non-linearities. By the employment of pre-post compensation to tolerate both residual chromatic dispersion and non-linearity, performance above the error free transmission limit at 40Gb/s bit rate have been attained for 2-, 3- and 4-channel MMT over spans lengths of up to 1200Km, 320 Km and 320 Km, respectively. While, at an aggregated bit rate of 100 Gb/s, error free transmission can be achieved for 2-, 3- and 4-channel MMT over spans lengths of up to 480 Km, 80 Km and 160 Km, respectively. At the same spectral efficiency, 4-channel MMT has realized a single channel maximum error free transmission over span lengths up to 320 Km and 160 Km at 40Gb/s and 100Gb/s, respectively, in contrast with 4-PAM attaining 240 Km and 80 Km at 40Gb/s and 100Gb/s, respectively

Mapping multiplexing technique (MMT): a novel intensity modulated transmission format for high-speed optical communication systems

There is a huge rapid growth in the deployment of data centers, mainly driven from the increasing demand of internet services as video streaming, e-commerce, Internet Of Things (IOT), social media, and cloud computing. This led data centers to experience an expeditious increase in the amount of network traffic that they have to sustain due to requirement of scaling with the processing speed of Complementary metal–oxide–semiconductor (CMOS) technology. On the other side, as more and more data centers and processing cores are on demand, as the power consumption is becoming a challenging issue. Unless novel power efficient methodologies are innovated, the information technology industry will be more liable to a future power crunch. As such, low complex novel transmission formats featuring both power efficiency and low cost are considered the major characteristics enabling large-scale, high performance data transmission environment for short-haul optical interconnects and metropolitan range data networks. In this thesis, a novel high-speed Intensity-Modulated Direct-Detection (IM/DD) transmission format named “Mapping Multiplexing Technique (MMT)” for high-speed optical fiber networks, is proposed and presented. Conceptually, MMT design challenges the high power consumption issue that exists in high-speed short and medium range networks. The proposed novel scheme provides low complex means for increasing the power efficiency of optical transceivers at an impactful tradeoff between power efficiency, spectral efficiency, and cost. The novel scheme has been registered as a patent (Malaysia PI2012700631) that can be employed for applications related but not limited to, short-haul optical interconnects in data centers and Metropolitan Area networks (MAN). A comprehensive mathematical model for N-channel MMT modulation format has been developed. In addition, a signal space model for the N-channel MMT has been presented to serve as a platform for comparison with other transmission formats under optical channel constraints. Especially, comparison with M-PAM, as meanwhile are of practical interest to expand the capacity for optical interconnects deployment which has been recently standardized for Ethernet IEEE 802.3bs 100Gb/s and in today ongoing investigation activities by IEEE 802.3 400Gb/s Ethernet Task Force. Performance metrics have been considered by the derivation of the average electrical and optical power for N-channel MMT symbols in comparison with Pulse Amplitude Modulation (M-PAM) format with respect to the information capacity. Asymptotic power efficiency evaluation in multi-dimensional signal space has been considered. For information capacity of 2, 3 and 4 bits/symbol, 2-channel, 3-channel and 4-channel MMT modulation formats can reduce the power penalty by 1.76 dB, 2.2 dB and 4 dB compared with 4-PAM, 8-PAM and 16-PAM, respectively. This enhancement is equivalent to 53%, 60% and 71% energy per bit reduction to the transmission of 2, 3 and 4 bits per symbol employing 2-, 3- and 4-channel MMT compared with 4-, 8- and 16-PAM format, respectively. One of the major dependable parameters that affect the immunity of a modulation format to fiber non-linearities, is the system baud rate. The propagation of pulses in fiber with bitrates in the order > 10G, is not only limited by the linear fiber impairments, however, it has strong proportionality with fiber intra-channel non-linearities (Self Phase Modulation (SPM), Intra-channel Cross-Phase Modulation (IXPM) and Intra-channel Four-Wave Mixing (IFWM)). Hence, in addition to the potential application of MMT in short-haul networks, the thesis validates the practicality of implementing N-channel MMT system accompanied by dispersion compensation methodologies to extend the reach of error free transmission (BER ≤ 10-12) for Metro-networks. N-Channel MMT has been validated by real environment simulation results to outperform the performance of M-PAM in tolerating fiber non-linearities. By the employment of pre-post compensation to tolerate both residual chromatic dispersion and non-linearity, performance above the error free transmission limit at 40Gb/s bit rate have been attained for 2-, 3- and 4-channel MMT over spans lengths of up to 1200Km, 320 Km and 320 Km, respectively. While, at an aggregated bit rate of 100 Gb/s, error free transmission can be achieved for 2-, 3- and 4-channel MMT over spans lengths of up to 480 Km, 80 Km and 160 Km, respectively. At the same spectral efficiency, 4-channel MMT has realized a single channel maximum error free transmission over span lengths up to 320 Km and 160 Km at 40Gb/s and 100Gb/s, respectively, in contrast with 4-PAM attaining 240 Km and 80 Km at 40Gb/s and 100Gb/s, respectively