Date post: | 19-Dec-2015 |
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In the near future All logic
operations solved using with optics
Have to start somewhere
Picture of something to signify amazing computing speeds
Why do we care? Problems with scaling of electrical
interconnects (EI) Ex: Telecommunications already
moved away from electrical lines Performance between chips is
already affected by EI Near future will be a problem on
chips
Solutions Several possibilities
New architectures• Minimize interconnections
New design approaches• Emphasize interconnection layout
New medium for interconnection• Optics
Background Research on optical interconnections
has been going on for >20 years With optoelectronic digital
computing Development of SEED’s and VCSEL’s Practical to implement
SEED/VCSEL picture?
Timing for optical signals Virtually independent of
temperature Virtually no degradation of signal on
the scale of meters Slower propagation, but very reliable
and predictable Could eliminate high power clock
circuits
Benefits of OI Optoelectronic devices can be used
as impedance transformers No inductance on an optical line Do not generate or detect radio-
frequency signals or interference Long or short does not matter
More benefits Larger synchronous zones, even on
multiple chips Allows “fire-hose” architectures Lower power dissipation after
“break-even length”• 100μm – 10’s of cm
Benefits cont. Voltage isolation Increasingly important due to
smaller power supplies Larger density for long distance on-
chip and off-chip interconnects No need for hierarchy of
interconnects
Scaling of OI transmitter/receiver Only viable if
technology for the design of TX/RX can keep up with future generations of silicon technology
Main Challenges for OI Young and expensive Systems that could take advantage
of optics will most likely have different architectures than today's
Problems and benefits are misperceived by those not involved in recent research
Technology Absence of low-cost and practical How to integrate
III-V devices Compatibility Hybrid integration
Solder-bonding
Misperceptions Wavelength is too large
Not true for longer interconnect lengths Conversion of optics to electronics is
inefficient Power, area, and time Current generation of technology