2008 High-throughput Nanophotonic Switch
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IBM scientists today took another significant advance towards sending information inside a computer chip by using light pulses instead of electrons by building the world’s tiniest nanophotonic switch with a footprint about 100X smaller than the cross section of a human hair. As many as 2000 would fit side-by-side in an area of one square millimeter making it possible to integrate thousands of them on a single chip, as would be required for future multi-core processors. The switch is an important building block to control the flow of information inside future chips and can significantly speed up the chip performance while using much less energy. This research is published in the volume 2 of the scientific journal Nature Photonics on April 1, 2008 Further reading The results of this research and all corresponding information are summarized on a special webpage High-throughput Nanophotonic Switch IBM press release 17 Mar 2008 "IBM Researchers Develop World’s Tiniest Nanophotonic Switch to route optical data between cores in future computer chips" |
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2007 Low-power ultra-compact 10Gbps silicon modulator
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IBM have built an ultra-compact and low-power silicon optical modulator, which performs the task of converting an electrical input signals into pulses of light. This device is a critical component in our work toward wiring a chip with light rather than copper wires. The modulator is capable of transmitting optical data at a rate of 10 billion bits per second (10 Giga bits per second).
This research is published in the volume 15 of the scientific journal Optics Express on December 5, 2007 Further reading The results of this research and all corresponding information are summarized on a special webpage Low power ultra-compact silicon modulator IBM press release 06 December 2007 "New IBM Research Technology Could Enable Today's Massive Supercomputers to be Tomorrow's Tiny Computer Chips" |
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2006 Compact optical buffer with micro-ring resonators
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IBM have built the all-optical buffer device capable of efficiently delaying 10 bits of 20 Giga bits per second optical signals within 0.03mm2 footprint on a silicon chip. This research is published in the premier issue of the scientific journal Nature Photonicson January 1, 2007. Further reading The results of this research and all corresponding information are summarized on a special webpage Compact optical buffer with ring resonators IBM press release 22 December 2006 "IBM Milestone Demonstrates Optical Device to Advance Computer Performance" |
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2005 Active Control of Slow Light on a Chip
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IBM researchers have demonstrated an integrated nanophotonic circuit fabricated on a silicon chip that can significantly slow down and actively control the speed of light. This research is published in the volume 438 of the scientific journal Nature on November 3, 2005 Further reading The results of this research and all corresponding information are summarized on a special webpage Slow light on a chip IBM press release 03 November 2005 "IBM Scientists Harness "Slow Light'' for Optical Communications" |
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2002-2004 Nanophotonic waveguides
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Photonic crystals consist of a number of tiny holes etched in silicon-on-insulator (SOI) wafer that are periodically arranged in a photonic lattice, analogous to the way atoms form a lattice of usual solids. In contrast to the atomic lattice, its photonic counterpart has a periodicity about 100 times larger matching the wavelength of the infrared light. Thus, in a way analogous to formation of electronic band gap in semiconductors, the photonic band gap is formed in photonic crystals, which, therefore, are often called "photonic semiconductors". The origin of the photonic band gap is Bragg diffraction of light on a periodic lattice of holes.
Photonic crystal waveguides The range of wavelengths corresponding to the photonic band gap can not propagate through the structure due to destructive interference. Removing one row of holes in a photonic lattice results in formation of a "defect" state within the photonic band gap for which the propagation is now allowed. Thus the photonic crystal waveguide is formed, whose properties are defined by carefully engineered geometry of the photonic lattice etched into a silicon layer. The light is strongly confined to the waveguide center. In the horizontal plane this confinement is provided by the photonic band gap, while vertically the light is confined by total internal reflection due to large refractive index contrast between silicon and surrounding material. Photonic wires Photonic wire waveguide is a bar of silicon with very small cross-section of the order of 0.5x0.2 microns. Since refractive index contrast is very large the infrared light at telecommunications wavelength around 1.5microns can still be confined and guided. As opposed to the photonic crystal waveguides the light in photonic wire waveguides is confined by total internal reflection due to large refractive index contrast between silicon and air. Extremely tight confinement of light in the area smaller than 0.1um2 provide the possibility to bend the light over very sharp corners. Sharp 90-degree bends with micron-scale radius Integration of discrete photonic components into a single chip is a long-standing goal of integrated optics. An important component of a compact photonic circuit is a small-radius low-loss waveguide bend that efficiently maneuvers light around sharp corners and connects different components together in a complete circuit. The smaller the bending radius, the higher integration density can be achieved on a chip. However the optical mode has a tendency to leak out of the waveguide at sharp bends. Therefore there is an optimum bending radius which is small enough to achieve integration, but not too small to result in excessive losses. Silicon nanophotonic approach allows to pursue an aggressive scaling of the waveguide cross-sections down to diffraction limit. Such extreme light confinement allows the minimal bending radius to be reduced to the micron range, opening an avenue to realize ultra-dense photonic integrated circuits on a single silicon chip. We explored various sharp bends employing photonic crystal waveguides as well as photonic wires. Bending losses in photonic wires were found to be below 0.005dB/turn for bending radius of R=5μm, increasing to 0.013±0.005dB/turn for R=2μm. Even for the smallest bending radius of R=1μm the bending loss is only 0.086±0.005dB/turn. These loss figures are the lowest reported to date and is a useful benchmark for further development of silicon nanophotonics components and circuits on SOI platform. Further reading Our published papers and on-line posters on the subject can be found in Publications |
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