Showing papers by "Jason S. Orcutt published in 2008"

Building Manycore Processor-to-DRAM Networks with Monolithic Silicon Photonics

Abstract: We present a new monolithic silicon photonics technology suited for integration with standard bulk CMOS processes, which reduces costs and improves opto-electrical coupling compared to previous approaches. Our technology supports dense wavelength-division multiplexing with dozens of wavelengths per waveguide. Simulation and experimental results reveal an order of magnitude better energy-efficiency than electrical links in the same technology generation. Exploiting key features of our photonics technology, we have developed a processor-memory network architecture for future manycore systems based on an opto-electrical global crossbar. We illustrate the advantages of the proposed network architecture using analytical models and simulations with synthetic traffic patterns. For a power-constrained system with 256 cores connected to 16 DRAM modules using an opto-electrical crossbar, aggregate network throughput can be improved by ap8-10times compared to an optimized purely electrical network.

Localized substrate removal technique enabling strong-confinement microphotonics in bulk Si CMOS processes

Abstract: A novel post-processing fabrication technique, based on XeF2 etching, has been developed to locally remove the silicon substrate beneath polysilicon waveguides, enabling integration of low-loss strong-confinement microphotonics into standard bulk-silicon CMOS process flows.

Demonstration of an electronic photonic integrated circuit in a commercial scaled bulk CMOS process

Abstract: We demonstrate the first photonic chip designed in a commercial bulk CMOS process (65 nm node) using standard process layers combined with scalable post-processing, enabling dense photonic integration with high-performance microprocessor electronics.

Effect of carrier lifetime on forward-biased silicon Mach-Zehnder modulators

Abstract: We present a systematic study of Mach-Zehnder silicon optical modulators based on carrier-injection. Detailed comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics. A figure of merit, static VπL, as low as 0.24Vmm is achieved. The effect of carrier lifetime variation with doping concentration is explored and found to be important for the modulator characteristics.

Reduction of substrate optical leakage in integrated photonic circuits through localized substrate removal

Abstract: Structures including optical waveguides disposed over substrates having a chamber or trench defined therein, and methods for formation thereof.

Photonic analog-to-digital conversion with electronic-photonic integrated circuits

Abstract: Photonic Analog-to-Digital Conversion (ADC) has a long history. The premise is that the superior noise performance of femtosecond lasers working at optical frequencies enables us to overcome the bottleneck set by jitter and bandwidth of electronic systems and components. We discuss and demonstrate strategies and devices that enable the implementation of photonic ADC systems with emerging electronic-photonic integrated circuits based on silicon photonics. Devices include 2-GHz repetition rate low noise femtosecond fiber lasers, Si-Modulators with up to 20 GHz modulation speed, 20 channel SiN-filter banks, and Ge-photodetectors. Results towards a 40GSa/sec sampling system with 8bits resolution are presented.