Spectral Characterization of silicon nonlinearity

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Spectral Characterization of silicon nonlinearity
in the near infrared region
Qiang Lin1,, Jidong Zhang2, Giovanni Piredda1,
Robert W. Boyd1, Philippe M. Fauchet1,2 , and
Govind P. Agrawal1
1. Institute of Optics, University of Rochester,
Rochester, NY 2. Dept. of ECE, University of
Rochester, Rochester, NY
Present position California Institute of
Technology
This work is supported in part by AFOSR
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Outline

• Motivation
• Experiments
• Results and Analysis
• Conclusions

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Motivation Si's nonlinearity

• Sis band edge indicates its great potential for
  applications at longer wavelengths
• Current knowledge of n2 and ßT is limited 1.5 µm
  and 1.3 µm
• No dispersion information available from Eg to ½
  Eg

• Our goal
• Characterize ?(3) for Si over a broad band,
  including absolute values and dispersion
• Offer guidelines for future nonlinear Si
  photonics research

Eg
Soref et. al. J. Opt. A Pure Appl. Opt. 8 p.840
(2006) Claps et. al. Opt. Express 11,
p.1731 (2003) Fukuda et. al. Opt. Express 13,
p.4629 (2005) Dulkeith et. al. Opt. Express 14,
p.5524, (2006) Tsang et. al. Appl. Phys. Lett.
80, 416 (2002) Dinu et. al. Appl. Phys. Lett.
82, p. 2954, (2003) Rieger et. al. Appl. Phys.
Lett. 84, p. 900 (2004) Xu et. al. Elec. Lett.
38, p.86 (2002)
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Experiments setup
(1-1-0) Si wafer
(1-0-0) Si wafer
Optical Kerr effect
Two photon absorption
Intensity
Self-focusing
Z position
Sheik-Bahae et. al. IEEE J. Quant. Electron. 26,
760 (1990)
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Experiments z-scan traces
Open aperture
Open aperture
Close aperture
Close aperture
Below 1/2 bandgap
Between 1x and 1/2 bandgap
?(3) shows significant dispersion
The illustration is from Jalali et. al. Nature
Photonics 1, 193 (2007)
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Results and Analysis

• ßT starts to drop from 1.7 µm
• n2 increases till 1.8 µm and then drops
• Confirms recent experimental result and theory
  model

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Comparison with previous work
4 3 2 1 0
X10-5
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
n2 (cm2/GW)
ßT (cm/GW)

• Dispersion of n2 agrees with SPM results
• Two band model confirms our result on the
  dispersion of n2 and ßT

Dulkeith et. al. Opt. Express 14, p.5524,
(2006) Dinu, IEEE J. Quant. Electron. 39, 1498
(2003).
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Results and Analysis
FOM suggests Si is a better nonlinear medium at
longer wavelengths
Eg/2
Soref et. al. J. Opt. A Pure Appl. Opt. 8 p.840
(2006)
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Conclusions

• We provide the first complete characterization on
  Sis ?(3) over a broad spectral range between 1.2
  µm and 2.4 µm
• Our results confirm recent theoretical model
• We offer guidelines for future work in silicon
  nonlinear photonics

Related talk Post-deadline presentation on the
application of this result to optical solitons
this Thursday (CPDA4).
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Acknowledgement

• We thank Professor Oskar Painter for his support.

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Thank you!
Post deadline talk on the solitons in Si
waveguides on Thursday
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Motivation nonlinear silicon photonics
Nonlinear Si photonics

• Fast almost instantaneous nonlinear process
• Compact and low power Sis large nonlinearity (?
  gt 10000X silica fiber)
• Integratible system-on-chip

Rong et. al. Nature 433, p.725, (2005) Claps et.
al. Opt. Express 11, p.731, (2003) Foster et. al.
Nature 441, p.960, (2006) Dulkeith et. al. Opt.
Express 14, p.5524, (2006) Lin et. al. Opt.
Express 14, p.4786, (2006)