This Topic Consider Situation of Interconnection of Computer Chip
- 電子connection 的問題： pin count proportional to bandwidth, large pin will be needed.
- Electronic interconnect limits over all system performance.
- Optical interconnection provides more bandwidth possibility.
- Optical approach can be more easily modulated for multiplexing, and bit modulation => Power Efficiency
- All optical systems require no additional EO conversion, which is power consumption.
- Electronic system needs buffer when bus is busy, this is proportional to the core number , but optics need only optical relay device to hold signal.
- Optical routing is immunity to computer scale, which can reach up few meter.
- Use waveguide incorporate total internal reflection can reach 45 degree turning.
- X^3 Effect changes refractive index through carrier concentration, while X^2 uses electrically to modulate the refractive index.
- refractive index of Silicon is 3.5, silicon nitride is 2.4. For a ring coupler, if difference of refractive index is large, the light is very confinemneted in the waveguide so the evalancent wave is small, causing the gap between waveguide and ring is small.
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