Browsing by Subject "Nanophotonics"
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Item Handshake and Circulation Flow Control in Nanaphotonic Interconnects(2012-10-19) Jayabalan, JagadishNanophotonics has been proposed to design low latency and high bandwidth Network-On-Chip (NOC) for future Chip Multi-Processors (CMPs). Recent nanophotonic NOC designs adopt the token-based arbitration coupled with credit-based flow control, which leads to low bandwidth utilization. This thesis proposes two handshake schemes for nanophotonic interconnects in CMPs, Global Handshake (GHS) and Distributed Handshake (DHS), which get rid of the traditional credit-based flow control, reduce the average token waiting time, and finally improve the network throughput. Furthermore, we enhance the basic handshake schemes with setaside buffer and circulation techniques to overcome the Head-Of-Line (HOL) blocking. The evaluations show that the proposed handshake schemes improve network throughput by up to 11x under synthetic workloads. With the extracted trace traffic from real applications, the handshake schemes can reduce the communication delay by up to 55%. The basic handshake schemes add only 0.4% hardware overhead for optical components and negligible power consumption. In addition, the performance of the handshake schemes is independent of on-chip buffer space, which makes them feasible in a large scale nanophotonic interconnect design.Item Hybrid Nanophotonic NOC Design for GPGPU(2012-07-16) Yuan, WenDue to the massive computational power, Graphics Processing Units (GPUs) have become a popular platform for executing general purpose parallel applications. The majority of on-chip communications in GPU architecture occur between memory controllers and compute cores, thus memory controllers become hot spots and bottle neck when conventional mesh interconnection networks are used. Leveraging this observation, we reduce the network latency and improve throughput by providing a nanophotonic ring network which connects all memory controllers. This new interconnection network employs a new routing algorithm that combines Dimension Ordered Routing (DOR) and nanophotonic ring algorithms. By exploring this new topology, we can achieve to reduce interconnection network latency by 17% on average (up to 32%) and improve IPC by 5% on average (up to 11.5%). We also analyze application characteristics of six CUDA benchmarks on the GPGPU-Sim simulator to obtain better perspective for designing high performance GPU interconnection network.Item Optical properties and collective modes of plasmonic meta-surfaces(2012-12) Mousavi, Seyyed Hossein; Shvets, G.; Bengtson, Roger; Demkov, Alex; Fink, Manfred; Ling, HaoPlasmonics is an important branch of optics and photonics, focusing on the electromagnetic response of metals or other materials with free carriers. This field has recently experienced a significant expansion due to its importance for applications. Plasmonics has shown great promises in green energies, biosensing, nanolasers, and imaging. The main advantage of plasmonics stems from the existence of unique excitations, referred to as plasmons, representing collective response of the free carriers to the electromagnetic field. While plasmons, both in the bulk and on the surface of the metals, have been known for decades, the recent advances in nano fabrication and material sciences at nano scale have enabled versatile engineering of these modes. Focus of my dissertation is surface plasmons whose properties can be tailored by judiciously nano-patterning metal films and surfaces. Such patterned structures, referred to as metasurfaces, are the main tool to control and boost the light-matter interaction. Appropriately designed metasurfaces provide many-fold electromagnetic energy enhancement on the surface which can be used to amplify numerous surface effects such as SEIRA and nonlinear optical phenomena, facilitate spectroscopy, and enhance absorption of light. In this thesis, I report approaches to shape and engineer the confinement, mode profile, and lifetime of the surface modes. I also investigate how the dielectric environment affects the properties of the modes. The effect of the geometry and topology of the nano patterns on the optical response of metasurfaces is also studied. Finally I study how manipulating symmetries of metasurfaces can be used to tailor polarization state of light and lifetime of the modes using an ultrathin metasurface, instead of bulky traditional optical elements. %The symmetry manipulation results in the plasmonic analogue of Electromagnetically Induced Transparency, a well-known phenomenon in atomic physics. The work summarized in this thesis has brought marked advances in understanding the physics behind the collective surface waves in nano-structured metasurfaces. It paves new avenues for engineering structures with desirable properties. The immediate application of my findings is the compactification of optical elements, and envisioning next-generation plasmonic-based on-chip devices.