Download On-chip Optical Interconnects

Si-based On-chip Optical
Interconnects
Shang Wang
ECE423
12/16/06
Disadvantages of Electrical Interconnects
Scaling Problem —— ”Aspect Ratio” Limit
Total RC time constant: Rl Cl l 2
Now scaling with s factor:
Rl  Rl s 2 , l  sl , Cl  Cl
Now Total RC time constant:
Rl Cl l 2  ( Rl s 2 )Cl ( sl ) 2  Rl Cl l 2 The same!!!
R  l A , C  l  B  1 RC  A l 2
However, optical interconnects do not have such problem!
Other Advantages of Optical Interconnects
 Timing Accuracy
 Design Simplification
• voltage isolation
• Absence of wave reflection and impedance
matching
• avoid inductive crosstalk
• frequency independence
On-chip Optical Interconnect Data Path
On-chip
Silicon
Laser
Silicon
Optical
Modulator
Silicon
Waveguide
Si-based
Photo
Detector
Driver
Amplifier
Electrical
Logic Cell
Electrical
Logic Cell
Si-based Light Source
——Raman Silicon Laser
Simulated Raman
Scattering (SRS)
A reversely biased p-i-n diode to
eliminate the TPA-induced FCA
Silicon Optical Modulator
N e  N h 
ne  Ne
nh  (N h )
 0 r
etox t
[VD  VFB ]
0.8
metal-oxide-semiconductor (MOS)
capacitor
  2neff L 
Mach-Zehnder Interferometer (MZI)
Si-based Photo detector
SiGe multiple quantum wells (MQW)
Conclusion
 The concept of optical interconnect brings a
brilliant future for the dense interconnects to
the silicon chips.
 The recent achievement in Intel of the silicon
laser, silicon optical modulator and siliconbased photodetector shows the potential of
monolithic integration of silicon-based
optoelectronics.
Thank you!