| 81. |
- Agelis, Sacki, et al.
(författare)
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Optoelectronic router with a reconfigurable shuffle network based on micro-optoelectromechanical systems
- 2004
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Ingår i: Journal of Optical Networking. - Washington, USA : Optical Society of America. - 1536-5379. ; 4:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- An optoelectronic router with a shuffle exchange network is presented and enhanced by the addition of micro-optoelectromechanical systems (MOEMS) in the network to add the ability to reconfigure the shuffle network. The MOEMS described here are fully connected any-to-any crossbar switches. The added reconfigurability provides the opportunity to adapt the system to different common application characteristics. Two representative application models are described: The first has symmetric properties, and the second has asymmetric properties. The router system is simulated with the specified applications and an analysis of the results is carried out. By use of MOEMS in the optical network, and thus reconfigurability, greater than 50% increased throughput performance and decreased average packet delay are obtained for the given application. Network congestion is avoided throughout the system if reconfigurability is used.
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| 82. |
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| 83. |
- Agelis, Sacki
(författare)
-
Reconfigurable Optical Interconnection Networks for High-Performance Embedded
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In embedded computer and communication system the capacity demand for interconnection networks is increasing continuously in order to achieve high-performance systems. Recent breakthroughs show that by using reconfigurability inside a single chip substantial performance gains can be added. However, in this thesis the focus is on system level reconfigurability (between chips or modules) and the performance gains that potentially can be achieved by having support for runtime reconfigurability on the system level.This thesis addresses the field of runtime system level reconfigurability with the use of optics in switches and routers for data- and telecommunications, and in multi-processor systems used for embedded signal processing. Several reconfigurable systems for switching and routing with support to adapt for asymmetric traffic patterns are proposed and compared to identify how design choices affect flexibility, performance etc. The proposed solutions are characterized by their multistage optical interconnection networks with reconfigurable shuffle patterns, where the reconfigurability is provided by micro-optical-electrical mechanical systems. More specifically, application-specific bottlenecks can be resolved by reconfiguring the interconnection network according to the current application demands. The benefits of the architectural solutions are confirmed by simulations that clearly show that the architectures can achieve high performance for both symmetric application characteristics and for several classes of asymmetric application characteristics. The final architectural solution is characterized by electronic packet-switches interconnected through an optical backplane, which is reconfigurable. Moreover, the thesis presents how several signal processing applications can be mapped to run concurrently in a time-shared scheme on a single reconfigurable multi-processor system that has high flexibility to adapt for the application currently at hand. The interconnection network is then adapted (reconfigured) according to the demands of the currently executed application in each time instance. The analysis shows that it is feasible to build such a system with today’s components.
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| 84. |
- Agelis, Sacki, et al.
(författare)
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Reconfigurable optical interconnection system supporting concurrent application-specific parallel computing
- 2005
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Ingår i: 17th Symposium on Computer Architecture and High Performance Computing. - Washington, DC, USA : IEEE Computer Society. - 076952446X ; , s. 44-51
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Konferensbidrag (refereegranskat)abstract
- Application specific architectures are highly desirable in embedded parallel computing systems at the same time as designers strive for using one embedded parallel computing platform for several applications. If this can be achieved, the cost can be decreased in comparison to using several different embedded parallel computing systems. This paper presents a novel approach of running several high-performance applications concurrently on one single parallel computing system. By using a reconfigurable backplane interconnection system, the applications can be run efficiently with high network flexibility since the interconnect network can be adapted to fit the application that is being processed for the moment. More precisely, this paper investigates how the space time adaptive processing (STAP) radar algorithm and the stripmap synthetic aperture radar (SAR) algorithm can be mapped on a multi-cluster processing system with a reconfigurable optical interconnection system realized by a micro-optical-electrical mechanical system (MOEMS) crossbars. The paper describes the reconfigurable platform, the two algorithms and how they individually can be mapped on the targeted multiprocessor system. It is also described how these two applications can be mapped simultaneously on the optical reconfigurable platform. Implications and requirements on communication bandwidth and processor performance in different critical points of the two applications are presented. The results of the analysis show that an implementation is feasible with today's MOEMS technology, and that the two applications can be successfully run in a time-sharing scheme, both at the processing side and at the access for interconnection bandwidth.
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| 85. |
- Agelis, Sacki, et al.
(författare)
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System-Level Runtime Reconfigurablity - Optical Interconnection Networks for Switching Applications
- 2004
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Ingår i: Proceedings of the International Conference on Engineering of Reconfigurable Systems and Algorithms, ERSA'04. - Athens, USA : CSREA Press. - 1932415424 - 9781932415421 ; , s. 155-162
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Konferensbidrag (refereegranskat)abstract
- The performance requirements on data and telecommunication switches and routers are continuously increasing and it is evident that new ideas and architectures must come to light to satisfy these new demands. In this paper, a runtime reconfigurable modular design approach is presented, using state-of-the-art microoptical-electrical mechanical system (MOEMS) components. The paper introduces a novel field of reconfigurability, where reconfiguration is made on the system level instead of, e.g. fine-granularity reconfigurable logic. Different reconfigurable system solutions with support to adapt for asymmetric traffic patterns are proposed and compared to see how design choices affect flexibility, performance etc. The proposed solutions are characterized by their multistage networks with reconfigurable shuffle patterns.
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| 86. |
- Agelis, Sacki, et al.
(författare)
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Visualizing the Potential of Reconfigurable Shuffle-Patterns in Optoelectronic Routers by the Use of MOEMS
- 2004
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Ingår i: Proceedings of the IASTED International Conference Communication Systems and Networks. - Calgary, Canada : ACTA Press. - 0889864500 ; , s. 148-154
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Konferensbidrag (refereegranskat)abstract
- A reconfigurable high performance multistage router architecture is presented and simulated. The router backbone network is an optical shuffle exchange network that has the power of reconfigurability through the use of micro-optical-electrical mechanical systems (MOEMS). The router is subjected to different application classes. The application classes have different characteristics in terms of symmetric/asymmetric traffic properties. We compare our reconfigurable shuffle-pattern for all three application classes for the specified router architecture.
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| 87. |
- Aghaeipour, Mahtab, et al.
(författare)
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Comparative study of absorption efficiency of inclined and vertical InP nanowires
- 2017
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Ingår i: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VI. - Bellingham, WA : SPIE - International Society for Optical Engineering. - 9781510606401 ; 10099
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Konferensbidrag (refereegranskat)abstract
- Geometrically designed III-V nanowire arrays are promising candidates for optoelectronics due to their possibility to excite nanophotonic resonances in absorption spectra. Strong absorption resonances can be obtained by proper tailoring of nanowire diameter, length and pitch. Such enhancement of the light absorption is, however, accompanied by undesired resonance dips at specific wavelengths. In this work, we theoretically show that tilting of the nanowires mitigates the absorption dips by exciting strong Mie resonances. In particular, we derive a theoretical optimum inclination angle of about 30 degrees at which the inclined nanowires gain 8% in absorption efficiency compared to vertically standing nanowires in a spectral region matching the intensity distribution of the sun. The enhancement is due to engineering the excited modes inside the nanowires regarding the symmetry properties of the nanowire/light system without increasing the absorbing material. We expect our results to be important for nanowire-based photovoltaic applications. © 2017 SPIE.
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| 88. |
- Aghaeipour, Mahtab, et al.
(författare)
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Considering symmetry properties of inp nanowire/light incidence systems to gain broadband absorption
- 2017
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Ingår i: IEEE Photonics Journal. - Piscataway : IEEE. - 1943-0655. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- Geometrically designed III-V nanowire arrays are promising candidates for disruptive optoelectronics due to the possibility of obtaining a strongly enhanced absorption resulting from nanophotonic resonance effects. With normally incident light on such vertical nanowire arrays, the absorption spectra exhibit peaks that originate from excitation of HE1m waveguide modes in the constituent nanowires. However, the absorption spectra typically show dips between the absorption peaks. Conventionally, such weak absorption has been counteracted by either making the nanowires longer or by decreasing the pitch of the array, both alternatives effectively increasing the volume of absorbing material in the array. Here, we first study two approaches for compensating the absorption dips by exciting additional Mie resonances: 1) oblique light incidence on vertical InP nanowire arrays and 2) normal light incidence on inclined InP nanowire arrays. We then show that branched nanowires offer a novel route to achieve broadband absorption by taking advantage of simultaneous excitations of Mie resonances in the branches and guided HE1m modes in the stem. Finite element method calculations show that the absorption efficiency is enhanced from 0.72 for vertical nanowires to 0.78 for branched nanowires under normal light incidence. Our work provides new insight for the development of novel efficient photovoltaics with high efficiency and reduced active material volume.
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| 89. |
- Aghaeipour, Mahtab, et al.
(författare)
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Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors
- 2018
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Ingår i: Nanophotonics. - Berlin : Walter de Gruyter GmbH. - 2192-8614. ; 7:5, s. 819-825
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Tidskriftsartikel (refereegranskat)abstract
- A near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III-V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.
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| 90. |
- Aghaeipour, Mahtab, et al.
(författare)
-
Enhanced optical absorption in nanowires over a desire range of wavelengths
- 2017
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Ingår i: MOC2017 : technical digest of the Twenty-Second Microoptics Conference. - : IEEE. - 9784863486096 - 9781509049240 ; , s. 360-361
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Konferensbidrag (refereegranskat)abstract
- Engineering optical absorption in nanowires, over a desire range of wavelengths is of importance to design high-performance nanowire-based photovoltaics. To this end, we integrate the nanowires with distributed Bragg reflectors to enhance absorption spectra of the nanowires and relate the consequent enhancement to increasing the optical path lengths of the modes. © 2017 The Japan Society of Applied Physics.
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