Multi-stage switching networks for waveguide optical technology

Multi-stage switching is very suitable for implementing interconnection systems operating at different physical scale (from rack-to-rack to on-chip) and with several technologies (either photonics or electronics). Several multistage architectures have been proposed to design these systems in a highly modular and efficient way. Since these proposals are general and applicable to a vast range of technologies, optimizations are possible once a specific technology is considered. In this work, we aim at optimizing multi-stage banyan and EGS architectures in case of optical waveguide technology implementation. We propose a method to decrease the number of waveguide crossovers, while avoiding an excessive increase of waveguide bends

Optical Interconnection Networks Based on Microring Resonators

Abstract — Interconnection networks must transport an always increasing information density and connect a rising number of processing units. Electronic technologies have been able to sustain the traffic growth rate, but are getting close to their physical limits. In this context, optical interconnection networks are becoming progressively more attractive, especially because new photonic devices can be directly integrated in CMOS technology. Indeed, interest in microring resonators as switching components is rising, but their usability in full optical interconnection architectures is still limited by their physical characteristics. Indeed, differently from classical devices used for switching, switching elements based on microring resonators exhibit asymmetric power losses depending on the output ports input signals are directed to. In this paper, we study classical interconnection architectures such as crossbar, Benes and Clos networks exploiting microring resonators as building blocks. Since classical interconnection networks lack either scalability or complexity, we propose two new architectures to improve performance of microring based interconnection networks while keeping a reasonable complexity. I

Optical interconnection networks based on microring resonators

Optical microring resonators can be integrated on a chip to perform switching operations directly in the optical domain. Thus they become a building block to create switching elements in on-chip optical interconnection networks, which promise to overcome some of the limitations of current electronic networks. However, the peculiar asymmetric power losses of microring resonators impose new constraints on the design and control of on-chip optical networks. In this work, we study the design of multistage interconnection networks optimized for a particular metric that we name the degradation index, which characterizes the asymmetric behavior of microrings. We also propose a routing control algorithm to maximize the overall throughput, considering the maximum allowed degradation index as a constrain

Nanomechanical single-photon routing

The merger between integrated photonics and quantum optics promises new opportunities within photonic quantum technology with the very significant progress on excellent photon-emitter interfaces and advanced optical circuits. A key missing functionality is rapid circuitry reconfigurability that ultimately does not introduce loss or emitter decoherence, and operating at a speed matching the photon generation and quantum memory storage time of the on-chip quantum emitter. This ambitious goal requires entirely new active quantum-photonic devices by extending the traditional approaches to reconfigurability. Here, by merging nano-optomechanics and deterministic photon-emitter interfaces we demonstrate on-chip single-photon routing with low loss, small device footprint, and an intrinsic time response approaching the spin coherence time of solid-state quantum emitters. The device is an essential building block for constructing advanced quantum photonic architectures on-chip, towards, e.g., coherent multi-photon sources, deterministic photon-photon quantum gates, quantum repeater nodes, or scalable quantum networks.Comment: 7 pages, 3 figures, supplementary informatio

Scalability of Optical Interconnects Based on Microring Resonators

This letter investigates the use of optical microring resonators as switching elements (SEs) in large optical interconnection fabrics. We introduce a simple physical-layer model to assess scalability in crossbar- and Benes-based architectures.We also propose a new dilated SE that improves scalability to build fabrics of several terabits per second of aggregate capacit

Automated routing and control of silicon photonic switch fabrics

Automatic reconfiguration and feedback controlled routing is demonstrated in an 8×8 silicon photonic switch fabric based on Mach-Zehnder interferometers. The use of non-invasive Contactless Integrated Photonic Probes (CLIPPs) enables real-time monitoring of the state of each switching element individually. Local monitoring provides direct information on the routing path, allowing an easy sequential tuning and feedback controlled stabilization of the individual switching elements, thus making the switch fabric robust against thermal crosstalk, even in the absence of a cooling system for the silicon chip. Up to 24 CLIPPs are interrogated by a multichannel integrated ASIC wire-bonded to the photonic chip. Optical routing is demonstrated on simultaneous WDM input signals that are labelled directly on-chip by suitable pilot tones without affecting the quality of the signals. Neither preliminary circuit calibration nor lookup tables are required, being the proposed control scheme inherently insensible to channels power fluctuations

Optical signal processing via two-photon absorption in a semiconductor microcavity for the next generation of high-speed optical communications network

Due to the introduction of new broadband services, individual line data rates are expected to exceed 100 Gb/s in the near future. To operate at these high speeds, new optical signal processing techniques will have to be developed. This paper will demonstrate that two-photon absorption in a specially designed semiconductor microcavity is an ideal candidate for optical signal processing applications such as autocorrelation, sampling, and demultiplexing in high-speed wavelength-division-multiplexed (WDM) and hybrid WDM/optical time-division-multiplexed networks

Semiconductor optical amplifiers: performance and applications in optical packet switching [Invited]

Semiconductor optical amplifiers (SOAs) are a versatile core technology and the basis for the implementation of a number of key functionalities central to the evolution of highly wavelength-agile all-optical networks. We present an overview of the state of the art of SOAs and summarize a range of applications such as power boosters, preamplifiers, optical linear (gain-clamped) amplifiers, optical gates, and modules based on the hybrid integration of SOAs to yield high-level functionalities such as all-optical wavelength converters/regenerators and small space switching matrices. Their use in a number of proposed optical packet switching situations is also highlighted

GaN/AlN Multiple Quantum Wells and Nitride-Based Waveguide Structures for Ultrafast All-Optical Switch Utilizing Intersubband Transition

Intersubband transition （ISBT） in multiple quantum wells （MQW） has drawn much attention for ultrafast optoelectronic devices owing to its wide wavelength-tunability and extremely fast energy relaxation process. Recently, the extension of ISBT wavelength to near-infrared wavelength, especially 1.55 μm, is of particular interest because such wavelength is vital for the development of ultrafast photonic devices for silica-fiber-based optical-communication networks. Among various materials proposed for intersubband transition at 1.55 μm, GaN/AlN MQW structures are promising due to their large conduction band offset of approximately 2 eV. Furthermore, the large electron effective mass and the large LO phonon energy in nitrides make their intersubband relaxation extremely fast in the order of sub-picoseconds. This makes intersubband transition in nitrides immensely interesting for the development of ultrafast photonic devices operating at a bit rate higher than 1 Tb/s.//The intersubband transition at 1.55 μm and shorter wavelengths have been achieved by molecular beam epitaxy （MBE） with the shortest wavelength of 1.08 μm. On the other hand, growth by metalorganic vapor phase epitaxy （MOVPE） has not yielded satisfactory results as the shortest ISBT wavelength reported is merely 2.4 μm. The demonstration of 1.55-μm ISBT by MOVPE, however, is still attractive since much better crystalline quality for device fabrication can be achieved. Moreover, MOVPE also has another advantage over MBE in industrial point of view. Indeed, the ultrafast optical switching utilizing intersubband transition has been demonstrated by MBE-grown GaN ridge waveguide structure with a bit rate higher than 1 Tb/s. However, such device requires optical-pulse switching energy higher than 10pJ/μm2 to utilize the saturable intersubband absorption, which is still too large for the applications in conventional optical communication networks. Reduction of the switching energy is therefore another important issue for the intersubband transition devices. In order to reduce the switching energy, not only the waveguide fabrication process, but also the epitaxial growth technique and the device structure have to be improved.//In this dissertation, the GaN/AlN multiple quantum wells and nitride-based waveguide structures are studied and fabricated for the applications of ultrafast all-optical switch utilizing intersubband transition. The ultrafast intersubband transition device is realized by using AlN waveguide structure with GaN/AlN quantum wells. This AlN-waveguide-based intersubband transition device can operate in the optical communication wavelength range, covering 1.3 μm, the shortest wavelength ever demonstrated for the intersubband transition devices.//In order to perform epitaxial growth of such structure with high quality, MOVPE is more preferable than MBE because the AlN layer can be grown with much better quality by the MOVPE. However, since the MOVPE growth of GaN/AlN MQW for the 1.55-μm ISBT is very difficult, the AlN waveguide structure was fabricated with a combination of both MOVPE and MBE growth techniques: MOVPE growth for AlN buffer layer and MBE re-growth for GaN/AlN multiple quantum wells. With this combination, the high quality waveguide with intersubband absorption in a wavelength range of 1.3-1.55 μm is achieved.//In addition to the improvement in the epitaxial growth technique, this dissertation also discusses on the problems in growing the waveguide structure of both MOVPE and MBE. Moreover, the design and fabrication of nitride-based waveguide structures are studied in details to improve the waveguide quality. The high-optical-confinement waveguide structures are proposed and successfully fabricated for the first time thanks to the successful demonstration of epitaxial growth and the improvement of fabrication process. Additionally, a new waveguide characterization method using the supercontinuum light source is also proposed and demonstrated. With this new characterization method, not only are the direct measurements of intersubband absorption in waveguides realized, but the problems in waveguide quality of the MBE-grown waveguide are also revealed. This provides very useful information for the improvement of fabrication process, especially the epitaxial growth process. The achievements in each area of epitaxial growth, waveguide fabrication process, and characterization, have made contributions to the improvement of waveguide characteristic, leading to the successful demonstration of the first AlN-waveguide-based intersubband transition devices with high performance.報告番号: 甲21171 ; 学位授与年月日: 2006-03-23 ; 学位の種別: 課程博士 ; 学位の種類: 博士(工学) ; 学位記番号: 博工第6261号 ; 研究科・専攻: 工学系研究科電子工学専