IASTED International Multi-Conference on Wireless and Optical Communications, 2006
The authors would like to acknowledge the assistance of David Selviah, Ioannis Papakonstantinou a... more The authors would like to acknowledge the assistance of David Selviah, Ioannis Papakonstantinou and Guoyu Yu of the Optical Systems and Devices group at University College London who characterised the tolerances inherent to multimode polymer waveguides. The authors would also like to ...
As both data storage interconnect speeds increase and form factors in hard disk drive technologie... more As both data storage interconnect speeds increase and form factors in hard disk drive technologies continue to shrink, the density of printed channels on the storage array midplane goes up. The dominant interconnect protocol on storage array midplanes is expected to increase to 12 ...
ABSTRACT The evolution of data storage communication protocols and corresponding in-system bandwi... more ABSTRACT The evolution of data storage communication protocols and corresponding in-system bandwidth densities is set to impose prohibitive cost and performance constraints on future data storage system designs, fuelling proposals for hybrid electronic and optical architectures in data centers. The migration of optical interconnect into the system enclosure itself can substantially mitigate the communications bottlenecks resulting from both the increase in data rate and internal interconnect link lengths. In order to assess the viability of embedding optical links within prevailing data storage architectures, we present the design and assembly of a fully operational data storage array platform, in which all internal high speed links have been implemented optically. This required the deployment of mid-board optical transceivers, an electro-optical midplane and proprietary pluggable optical connectors for storage devices. We present the design of a high density optical layout to accommodate the midplane interconnect requirements of a data storage enclosure with support for 24 Small Form Factor (SFF) solid state or rotating disk drives and the design of a proprietary optical connector and interface cards, enabling standard drives to be plugged into an electro-optical midplane. Crucially, we have also modified the platform to accommodate longer optical interconnect lengths up to 50 meters in order to investigate future datacenter architectures based on disaggregation of modular subsystems. The optically enabled data storage system has been fully validated for both 6 Gb/s and 12 Gb/s SAS data traffic conveyed along internal optical links.
ABSTRACT Widespread adoption of electro-optical circuit boards based on embedded glass waveguide ... more ABSTRACT Widespread adoption of electro-optical circuit boards based on embedded glass waveguide technology would enable seamless optical connectivity from external fiber-optic networks to system embedded optical interconnect architectures. In this paper, we report on the fabrication of planar multimode waveguides within thin glass foils based on a two-step thermal ion exchange process. Novel lamination techniques were developed to allow glass waveguide panels to be reliably integrated into a conventional electronic multilayer printed circuit board. In addition, a complete suite of optical connector technologies were developed to enable both direct fiber-to-board and board-to-board connectivity. We present the design, development, and characterization of a fully integrated connection platform, comprising a $281 \times 233$ mm2 multilayer electro-optical backplane with integrated planar glass waveguides, a pluggable connector system, and five pluggable test cards. Both on-card and externally generated 850 and 1310-nm optical test data were conveyed through the connector and waveguide system and characterised for in-system and system-to-system optical connectivity at data rates up to 32 Gb/s per channel exhibiting bit error rates of less than $10^{-12}$ .
The authors would like to acknowledge the assistance of David Selviah, Ioannis Papakonstantinou a... more The authors would like to acknowledge the assistance of David Selviah, Ioannis Papakonstantinou and Guoyu Yu of the Optical Systems and Devices group at University College London who characterised the tolerances inherent to multimode polymer waveguides. The authors would also like to ...
2008 58th Electronic Components and Technology Conference, 2008
The paper introduces a low cost, precision alignment technique designed to be unaffected by tempe... more The paper introduces a low cost, precision alignment technique designed to be unaffected by temperature or process variations in the thickness of the PCB FR4 board, the thickness of the lower cladding between the PCB board and the waveguide core, the thickness of the upper cladding above the waveguide core, the relative lateral position of waveguides across the PCB, and the axial position of the cut entrance and exit faces of the waveguide.
Integrated Optics: Devices, Materials, and Technologies XVI, 2012
ABSTRACT In-plane bend loss represents the greatest commercial inhibitor to deploying multimode o... more ABSTRACT In-plane bend loss represents the greatest commercial inhibitor to deploying multimode optical waveguides on densely populated electro-optical printed circuit boards (OPCB) as the minimum bend radii currently possible are too large to be practical in common designs. We present a concept and fabrication method for creating novel polymer optical waveguide structures with reduced bend losses to enable higher density routing on an OPCB. These nested core waveguide structures comprise a core surrounded by a thin shell of cladding, which allows for two-fold modal containment by first a conventional low refractive index contrast (LIC) boundary followed by a secondary high refractive index contrast (HIC) boundary. The purpose of this is to reduce the in-plane bend losses incurred on tightly routed optical channels, while not incurring prohibitive dispersion, sidewall scattering and optical crosstalk penalties. We have designed and fabricated nested core multimode polymer waveguides, evaluated their performance in comparison to conventional step-index waveguides and simulated these structures using the beam propagation method. Preliminary results are presented of our measurements and simulations.
The authors would like to sincerely thank IBM Research-Zürich and vario-optics for their involvem... more The authors would like to sincerely thank IBM Research-Zürich and vario-optics for their involvement in the design and fabrication of the electro-optical circuit board and Samtec for the design of the connector engagement mechanism and assembly jigs. They also gratefully ...
Purposeto introduce the Innovative Electronics Manufacturing Research Centre (IeMRC) Flagship Pro... more Purposeto introduce the Innovative Electronics Manufacturing Research Centre (IeMRC) Flagship Project: Integrated Optical and Electronic Interconnect PCB Manufacturing (OPCB), its objectives, its consortium of 3 Universities and 10 companies and to describe the university research being carried out. This paper briefly reviews the motivation for developing novel polymer formulations, fabrication techniques, layout design rules and characterisation techniques for hybrid electronic and optical printed circuit boards using multimode polymer optical waveguide interconnects.
ABSTRACT An optical backplane ecosystem is described and demonstrated that is capable of multi-Tb... more ABSTRACT An optical backplane ecosystem is described and demonstrated that is capable of multi-Tb/s bandwidth and is based on embedded polymer waveguides, passive optical backplane connectors, and midboard optical transceivers with bandwidth up to 28 Gb/s per lane. These systems provide the highest bandwidth-density, lowest power consumption, while maintaining the signal integrity. Ecosystems built around this architecture will provide the bandwidth-density required for next generation fabric interconnect for storage, switching, and routing applications in future high capacity generations of Data Centers and HPC systems. To demonstrate the applicability of this technology, it was used to provide embedded optical connectivity within a functional data storage enclosure.
The first, to our knowledge, passive, precision, selfalignment technique for direct coupling of v... more The first, to our knowledge, passive, precision, selfalignment technique for direct coupling of vertical cavity surface emitting laser (VCSEL) and photodiode (PD) arrays to an array of polymer buried channel waveguides on a rigid printed circuit board (PCB) is reported. It gives insertion losses as good as the best achieved previously, to within experimental measurement accuracy, but without the need for costly active alignment nor waveguide facet polishing and so is a major step towards a commercially realizable low cost connector. Such an optical connector with four duplex channels each operating at 10 Gb/s (80 Gb/s aggregate) was designed, constructed, and its alignment precision assessed. The alignment technique is applicable to polymer waveguide interconnections on both rigid and flexible multilayer printed circuit boards (PCBs). The dependence of optical coupling loss on misalignments in , and of the VCSEL and PD arrays allows the precision of alignment to be assessed and its reproducibility on multiple mating cycles of the connector is reported. The first recorded measurements of crosstalk between waveguides when the connector is misaligned are reported. Lateral misalignments of the connector to within its tolerance are shown to have no effect on the signal to crosstalk ratio (SCR), to within experimental measurement accuracy. The insertion loss repeatability is similar to that of single mode fiber mechanically transferable (MT) connectors.
Optoelectronic Interconnects and Component Integration IX, 2010
2 Design challenges in data storage systems Electro-optical backplane with polymer waveguides... more 2 Design challenges in data storage systems Electro-optical backplane with polymer waveguides Active in-plane optical backplane connector Demonstration platform Spring loaded platform Microcontroller SPIE Photonics West 2010 Opto: 7607-18 22 CONNECTOR ENGAGEMENT MECHANISM Undocked Cam followers Cam track Docked Cam followers guided along cam track Allows for orthogonal movement of optical platform Ramped plug for reversible connection Ramped plug SPIE Photonics West 2010 Opto: 7607-18
IASTED International Multi-Conference on Wireless and Optical Communications, 2006
The authors would like to acknowledge the assistance of David Selviah, Ioannis Papakonstantinou a... more The authors would like to acknowledge the assistance of David Selviah, Ioannis Papakonstantinou and Guoyu Yu of the Optical Systems and Devices group at University College London who characterised the tolerances inherent to multimode polymer waveguides. The authors would also like to ...
As both data storage interconnect speeds increase and form factors in hard disk drive technologie... more As both data storage interconnect speeds increase and form factors in hard disk drive technologies continue to shrink, the density of printed channels on the storage array midplane goes up. The dominant interconnect protocol on storage array midplanes is expected to increase to 12 ...
ABSTRACT The evolution of data storage communication protocols and corresponding in-system bandwi... more ABSTRACT The evolution of data storage communication protocols and corresponding in-system bandwidth densities is set to impose prohibitive cost and performance constraints on future data storage system designs, fuelling proposals for hybrid electronic and optical architectures in data centers. The migration of optical interconnect into the system enclosure itself can substantially mitigate the communications bottlenecks resulting from both the increase in data rate and internal interconnect link lengths. In order to assess the viability of embedding optical links within prevailing data storage architectures, we present the design and assembly of a fully operational data storage array platform, in which all internal high speed links have been implemented optically. This required the deployment of mid-board optical transceivers, an electro-optical midplane and proprietary pluggable optical connectors for storage devices. We present the design of a high density optical layout to accommodate the midplane interconnect requirements of a data storage enclosure with support for 24 Small Form Factor (SFF) solid state or rotating disk drives and the design of a proprietary optical connector and interface cards, enabling standard drives to be plugged into an electro-optical midplane. Crucially, we have also modified the platform to accommodate longer optical interconnect lengths up to 50 meters in order to investigate future datacenter architectures based on disaggregation of modular subsystems. The optically enabled data storage system has been fully validated for both 6 Gb/s and 12 Gb/s SAS data traffic conveyed along internal optical links.
ABSTRACT Widespread adoption of electro-optical circuit boards based on embedded glass waveguide ... more ABSTRACT Widespread adoption of electro-optical circuit boards based on embedded glass waveguide technology would enable seamless optical connectivity from external fiber-optic networks to system embedded optical interconnect architectures. In this paper, we report on the fabrication of planar multimode waveguides within thin glass foils based on a two-step thermal ion exchange process. Novel lamination techniques were developed to allow glass waveguide panels to be reliably integrated into a conventional electronic multilayer printed circuit board. In addition, a complete suite of optical connector technologies were developed to enable both direct fiber-to-board and board-to-board connectivity. We present the design, development, and characterization of a fully integrated connection platform, comprising a $281 \times 233$ mm2 multilayer electro-optical backplane with integrated planar glass waveguides, a pluggable connector system, and five pluggable test cards. Both on-card and externally generated 850 and 1310-nm optical test data were conveyed through the connector and waveguide system and characterised for in-system and system-to-system optical connectivity at data rates up to 32 Gb/s per channel exhibiting bit error rates of less than $10^{-12}$ .
The authors would like to acknowledge the assistance of David Selviah, Ioannis Papakonstantinou a... more The authors would like to acknowledge the assistance of David Selviah, Ioannis Papakonstantinou and Guoyu Yu of the Optical Systems and Devices group at University College London who characterised the tolerances inherent to multimode polymer waveguides. The authors would also like to ...
2008 58th Electronic Components and Technology Conference, 2008
The paper introduces a low cost, precision alignment technique designed to be unaffected by tempe... more The paper introduces a low cost, precision alignment technique designed to be unaffected by temperature or process variations in the thickness of the PCB FR4 board, the thickness of the lower cladding between the PCB board and the waveguide core, the thickness of the upper cladding above the waveguide core, the relative lateral position of waveguides across the PCB, and the axial position of the cut entrance and exit faces of the waveguide.
Integrated Optics: Devices, Materials, and Technologies XVI, 2012
ABSTRACT In-plane bend loss represents the greatest commercial inhibitor to deploying multimode o... more ABSTRACT In-plane bend loss represents the greatest commercial inhibitor to deploying multimode optical waveguides on densely populated electro-optical printed circuit boards (OPCB) as the minimum bend radii currently possible are too large to be practical in common designs. We present a concept and fabrication method for creating novel polymer optical waveguide structures with reduced bend losses to enable higher density routing on an OPCB. These nested core waveguide structures comprise a core surrounded by a thin shell of cladding, which allows for two-fold modal containment by first a conventional low refractive index contrast (LIC) boundary followed by a secondary high refractive index contrast (HIC) boundary. The purpose of this is to reduce the in-plane bend losses incurred on tightly routed optical channels, while not incurring prohibitive dispersion, sidewall scattering and optical crosstalk penalties. We have designed and fabricated nested core multimode polymer waveguides, evaluated their performance in comparison to conventional step-index waveguides and simulated these structures using the beam propagation method. Preliminary results are presented of our measurements and simulations.
The authors would like to sincerely thank IBM Research-Zürich and vario-optics for their involvem... more The authors would like to sincerely thank IBM Research-Zürich and vario-optics for their involvement in the design and fabrication of the electro-optical circuit board and Samtec for the design of the connector engagement mechanism and assembly jigs. They also gratefully ...
Purposeto introduce the Innovative Electronics Manufacturing Research Centre (IeMRC) Flagship Pro... more Purposeto introduce the Innovative Electronics Manufacturing Research Centre (IeMRC) Flagship Project: Integrated Optical and Electronic Interconnect PCB Manufacturing (OPCB), its objectives, its consortium of 3 Universities and 10 companies and to describe the university research being carried out. This paper briefly reviews the motivation for developing novel polymer formulations, fabrication techniques, layout design rules and characterisation techniques for hybrid electronic and optical printed circuit boards using multimode polymer optical waveguide interconnects.
ABSTRACT An optical backplane ecosystem is described and demonstrated that is capable of multi-Tb... more ABSTRACT An optical backplane ecosystem is described and demonstrated that is capable of multi-Tb/s bandwidth and is based on embedded polymer waveguides, passive optical backplane connectors, and midboard optical transceivers with bandwidth up to 28 Gb/s per lane. These systems provide the highest bandwidth-density, lowest power consumption, while maintaining the signal integrity. Ecosystems built around this architecture will provide the bandwidth-density required for next generation fabric interconnect for storage, switching, and routing applications in future high capacity generations of Data Centers and HPC systems. To demonstrate the applicability of this technology, it was used to provide embedded optical connectivity within a functional data storage enclosure.
The first, to our knowledge, passive, precision, selfalignment technique for direct coupling of v... more The first, to our knowledge, passive, precision, selfalignment technique for direct coupling of vertical cavity surface emitting laser (VCSEL) and photodiode (PD) arrays to an array of polymer buried channel waveguides on a rigid printed circuit board (PCB) is reported. It gives insertion losses as good as the best achieved previously, to within experimental measurement accuracy, but without the need for costly active alignment nor waveguide facet polishing and so is a major step towards a commercially realizable low cost connector. Such an optical connector with four duplex channels each operating at 10 Gb/s (80 Gb/s aggregate) was designed, constructed, and its alignment precision assessed. The alignment technique is applicable to polymer waveguide interconnections on both rigid and flexible multilayer printed circuit boards (PCBs). The dependence of optical coupling loss on misalignments in , and of the VCSEL and PD arrays allows the precision of alignment to be assessed and its reproducibility on multiple mating cycles of the connector is reported. The first recorded measurements of crosstalk between waveguides when the connector is misaligned are reported. Lateral misalignments of the connector to within its tolerance are shown to have no effect on the signal to crosstalk ratio (SCR), to within experimental measurement accuracy. The insertion loss repeatability is similar to that of single mode fiber mechanically transferable (MT) connectors.
Optoelectronic Interconnects and Component Integration IX, 2010
2 Design challenges in data storage systems Electro-optical backplane with polymer waveguides... more 2 Design challenges in data storage systems Electro-optical backplane with polymer waveguides Active in-plane optical backplane connector Demonstration platform Spring loaded platform Microcontroller SPIE Photonics West 2010 Opto: 7607-18 22 CONNECTOR ENGAGEMENT MECHANISM Undocked Cam followers Cam track Docked Cam followers guided along cam track Allows for orthogonal movement of optical platform Ramped plug for reversible connection Ramped plug SPIE Photonics West 2010 Opto: 7607-18
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Papers by Richard Pitwon