A multi-channel free-space micro-optical module for dense MCM-level optical interconnections has been designed and fabricated. Extensive modeling proves that the module is scalable with a potential for multi-Tb/s.cm2 aggregate bit rate capacity while alignment and fabrication tolerances are compatible with present-day mass replication techniques. The micro-optical module is an assembly of refractive lenslet-arrays and a high-quality micro-prism. Both components are prototyped using deep lithography with protons and are monolithically integrated using vacuum casting replication technique. The resulting 16-channel high optical-grade plastic module shows optical transfer efficiencies of 46% and inter-channel cross talks as low as -22 dB, sufficient to establish workable multi-channel MCM-level interconnections. This micro-optical module was used in a feasibility demonstrator to establish intra-chip optical interconnections on a 0.6μm CMOS opto-electronic field programmable gate array. This opto-electronic chip combines fully functional digital logic, driver and receiver circuitry and flip-chipped VCSEL and detector arrays. With this test-vehicle multichannel on-chip data-communication has been achieved for the first time to our knowledge. The bit rate per channel was limited to 10Mb/s because of the limited speed of the chip tester.
We fabricated and replicated in semiconductor compatible plastics a multi-channel free-space optical interconnection module designed to establish intra-chip interconnections on an Opto-Electronic Field Programmable Gate Array (OE-FPGA). The micro-optical component is an assembly of a refractive lenslet-array and a high-quality microprism. Both components were prototyped using deep lithography with protons and were monolithically integrated using a vacuum casting replication technique. The resulting 16 channel module shows optical transfer efficiencies of 50% and inter-channel cross-talks as low as 22 dB. These characteristics are sufficient to establish multi-channel intra-chip interconnects with OE-FPGA's. The OE-FPGA we used was designed within a European co-founded MEL-ARI consortium, working towards a manufacturable solution for optical interconnects between CMOS IC's. The optoelectronic chip combines fully functional FPGA digital logic with the drivers, receivers and flip-chipped optoelectronic components. With a careful alignment of the micro-optical free-space module above the OE-VLSI chip, we demonstrated for the first time to our knowledge multi-channel free-space intra-chip optical interconnections. Data-communication was achieved with 4 simultaneous channels working at 10Mb/s. The bitrate was limited by the chiptester.
Furthermore we investigated the possibilities of a more advanced interconnection module prototyped by combining an in-house fabricated baseplate with microlenses and a commercially available micro 3D glass prism. With this approach the channel count is no longer limited by the thickness of the prism we can fabricate with deep lithography with protons. To conclude we report on the integration of this glass prism and our baseplate and on the first results obtained with this interconnection module.
In this paper we assess the replication of micro-optical structures through vacuum casting. To that aim we have replicated, besides optical components and structures fabricated with DLP a variety of other optical components: micro-jet lenses, glass gratings, glass lenses and hybrid integrated systems. Shrinkage is always present on the replicated elements and therefore must be compensated in the master element, if one wants to have correct final dimensions. Furthermore it is of great importance that the replica is crystal-clear and without flow lines or other distortions. This can be obtained by tuning the different process parameters and by working with different types and qualities of polyurethane. In this paper we will highlight our findings on the assessment of the vacuum casting technology with respect to shrinkage, replication quality and transmission efficiency.
We fabricated and replicated in semiconductor compatible plastics a multichannel free-space optical interconnection module designed to establish intra-chip interconnections on an Opto-Electronic Field Programmable Gate Array (OE-FPGA). The micro-optical component is an assembly of a refractive lenslet-array and a high-quality microprism. Both components were prototyped using deep lithography with protons and were monolithically integrated using a vacuum casting replication technique. The resulting 16-channel module shows optical transfer efficiencies of 50% and interchannel crosstalks as low as -22 dB. These characteristics are sufficient to establish multichannel intra-chip interconnects with OE- FPGAs. The OE-FPGA we used was designed within a European co- founded MEL-ARI consortium, working towards a manufacturable solution for optical interconnects between CMOS ICs. The optoelectronic chip combines fully functional FPGA digital logic with the drivers, receivers and flip-chipped optoelectronic components. It features 2 optical inputs and 2 optical outputs per FPGA cell, amounting to 256 photonic I/O links based on multimode 980-nm VCSELs and InGaAs detectors.
In this paper we present our latest results on the fabrication and characterization of plastic microlenslet arrays using Deep Lithography with Protons (DLP) and highlight their geometrical dimensions, their surface profile and their uniformity. We also present quantitative information on their optical characteristics such as focal length and spherical aberration as measured with a Mach-Zehnder interferometer. Furthermore we demonstrate the flexibility of the DLP technology to fabricate arrays of microlenses that feature different pitches and different sags. Although the DLP technology is a valuable tool to rapidly prototype refractive micro-optical components, the approach is unpractical for mass-fabrication. We therefore introduce a replication technique, called vacuum casting, which is very appropriate when only a few tens of copies have to be made, and we bring forward the first quantitative characteristics of these microlens replicas.
We report on the design, the fabrication, the characterization and the demonstration of scalable multi-channel free-space interconnection components with the potential for Tb/s.cm2 aggregate bit rate capacity over inter-chip interconnection distances. The demonstrator components are fabricated in a high quality optical plastic, PMMA, using an ion-based rapid prototyping technology that we call deep proton lithography. With the presently achieved Gigabit/s data rates for each of the individual 16 channels with a BER smaller than 10(superscript -13 and with inter-channel cross-talk lower than -22dB the module aims at optically interconnecting 2-D opto-electronic VCSEL and receiver arrays, flip-chip mounted on CMOS circuitry. Furthermore, using ray-tracing software and radiometric simulation tools, we perform a sensitivity analysis for misalignment and fabrication errors on these plastic micro-optical modules and we study industrial fabrication and material issues related to the mass-replication of these components through injection-molding techniques. Finally we provide evidence that these components can be mass-fabricated in dedicated, highly-advanced optical plastics at low cost and with the required precision.
We report on the design, the fabrication, the characterization and the demonstration of scalable multi-channel free-space interconnection components with the potential for Tb/s.cm2 aggregate bit rate capacity over inter-chip interconnection distances. The demonstrator components are fabricated in a high quality optical plastic, PMMA, using an ion-based rapid prototyping technology that we call deep proton lithography. With the presently achieved Gigabit/s data rates for each of the individual 16 channels with a BER smaller than 10-13 and with inter-channel cross-talk lower than -22dB the module aims at optically interconnecting 2-D opto-electronic VCSEL and receiver arrays, flip-chip mounted on CMOS circuitry. Furthermore, using ray-tracing software and radiometric simulation tools, we perform a sensitivity analysis for misalignment and fabrication errors on these plastic micro-optical modules and we study industrial fabrication and material issues related to the mass- replication of these components through injection-molding techniques. Finally we provide evidence that these components can be mass-fabricated in dedicated, highly-advanced optical plastics at low cost and with the required precision.
Deep Lithography with Protons (DLP) is a rapid prototyping technology for the fabrication of 3D micro-optical precision components. In this paper we will demonstrate how we made this DLP technology compatible with commercially available injection-molding and vacuum casting techniques, allowing to mass-replicate high-quality micro-optical modules at low cost. We will illustrate our technology by presenting optical characteristics of different refractive components made in optical-grade plastics such as polymethyl-methacrylate (PMMA), polycarbonate (PC) and semiconductor compatible plastics with high glass-transition temperatures such as COC.
We report on the design, the fabrication, the characterization and the demonstration of a scalable multi- channel free-space interconnection components with the potential for Tb/x.cm2 aggregate bit rate capacity over inter-chip interconnection distances. The demonstrator components are fabricated in a high quality optical plastic, PMMA, using an ion-based rapid prototyping technology that we call deep proton lithography. With the presently achieved Gigabit/s data rates for each of the individual 16 channels with a BER smaller than 10-13 and with inter-channel cross-talk lower than -22dB the module aims at optically interconnecting 2-D opto-electronic VCSEL and receiver arrays, flip-chip mounted on CMOS circuitry. Furthermore, using ray-tracing software and radiometric simulation tools, we perform a sensitivity analysis fo misalignment and fabrication errors on these plastic micro- optical modules and we study industrial fabrication and material issues related to the mass-replication of these components through injection-molding techniques. Finally we provide evidence that these components can be mass- fabricated in dedicated, highly-advanced optical plastics at low cost and with the required precision.
We design and realize a scalable multi-channel free-space interconnection prototype with the potential for Tb/s.cm2 aggregate bit rate capacity over inter- and intra-MCM interconnection distances. The component is prototyped in a high quality optical plastic, PMMA, using deep lithography with protons. At present data communication is achieved at 622 Mb/s per channel with a BER smaller than 10-13 for the 16 channels with inter-channel cross-talks as low as -22dB. We perform a sensitivity analysis for misalignments and study the impact of fabrication errors on the performance of the interconnection module in case injection moulding would be the preferred mass-fabrication technique. We provide evidence that these modules can be mass-fabricated with the required precision in optical plastics suited for heterogeneous integration with semiconductor materials.
We simulate and compare optical transmission efficiencies, throughputs and interconnection lengths of free-space and POF-based guided-wave multi-chip-module optical interconnection systems for different types of microcavity emitters.
We simulate and compare optical transmission efficiencies, throughputs and interconnection lengths of free-space and POF-based guided-wave optical interconnection systems for different types of microcavity emitters.
The technology of deep proton lithography in PMMA (poly methyl methacrylate) is a fabrication method for monolithic integrated refractive micro-optical elements and micro-mechanical holder structures, which allows structural depths in the order of several hundred microns[l.21. Different optical functions can he fabricated in one block and form monolithic integrated optical systems. In addition mechanical support structures and alignment features can he integrated with these optical systems. This paper will focus mainly on the technological requirements of the irradiation, development and diffusion setups. which are necessary to achieve predictable and reproducible results with deep proton lithography.
We demonstrate a 2.5 Gb/s optical intra-MCM data link with a four-channel micro-optical bridge. This bridge was fabricated by deep proton lithography and monolithically integrates cylindrical lenses and micro-mirrors.
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