Title: Silicon Nanophotonic Structures Michal Lipson School of Electrical and Computer Engineering Cornell
1Silicon Nanophotonic Structures Michal
LipsonSchool of Electrical and Computer
EngineeringCornell Universitynanophotonics.ece.c
ornell.edu
2Using Silicon-the microelectronics platform for
optics
- 1.3 and 1.55 ?m wavelengths
- High-index contrast compact structures
Where are we standing?
Need for active devices! Modulators, switches
3Standard Solution
10??m
0.5??m
Extremely long
4Fiber to Waveguide Coupling Reverse Tapering
5Simulations
0.2dB losses
6Fabrication of the nm Optical Solder
Waveguide
Coupler
Measurements of less than 2dB coupling
efficiency Smallest Silicon optical coupler
Almeida, V. R., Panepucci, R. R., and M. Lipson,
Optics Letters, 28, 1302 (2003).
7All-Optical Modulation
Opening gate from opaque to transparent
Previous works in Silicon large, high power
devices
N. D. Sankey, D. F. Prelewitz, and T. G. Brown,
Appl. Phys. Lett. 60, 1427-1429 (1992)
8All-optical Modulation
Controlling light with light
Closing gate from transparent to opaque
9High confinement waveguides for functional devices
450 nm ? 250 nm
SiO2
Si
- Intensity in the waveguides can be orders of
magnitude higher than the intensity in the core
of single mode optical fiber. - Nonlinear optical effect can be excited with
moderate optical power in short distances.
Prof. Michal Lipson ? Cornell Nanophotonics
Group ? http//nanophotonics.ece.cornell.edu
10Switching light in Silicon using free-carriers
Mechanism Plasma Dispersion Effect (linear
process) Refractive index change by free
carrier injection
Challenge
Weak index dependence on free carrier
concentration
R.A. Soref, et al , IEEE Journal of Quantum
Electronics, vol. 23, (1987)
11Compact all-optical modulator on Silicon
High confinement waveguides Enhancement of the
two-photon absorption
High Q cavity Increase in sensitivity of the
device to small index changes
Pumpprobe (?probe ? pump1.5µm)
Almeida, V. R., Barrios, C. A., Panepucci, R. R.,
Lipson, M., All-Optical control of light on a
Silicon chip, Nature, pp1081-1084 (Oct 28th,
2004) Almeida, V. R., Barrios, C. A., Panepucci,
R. R., Lipson, M., Foster, M.A., Quzounov, D. G.,
and A. L. Gaeta, All-optical switching on a
silicon chip, Optics Letters 29 (Dec. 2004)
12Fabrication
Ebeam Lithography
EBeam Resist
Scanning electron micrograph of a ring resonator
Si 250nm
Width 450nm
BOx 3µm
Gap 200nm
Si Substrate
Diameter 12µm
Width 450nm
Etching using RIE
BOx 3µm
Si Substrate
Oxide Deposition
BOx 3µm
Si Substrate
13Strong Light Confining Structures
,
Q2300
Device is very sensitive to small perturbations
in the Silicon
14Demonstration of Switch Opening Gate
400 ps
15Closing Gate
Dt
0.1psec
Pump off
Pump off
100
Pump on
Transparent
Transparent
50
Probe transmisison
Probe transmission
Opaque
Probe wavelength (nm)
0
0
1
2
3
Time (ns)
16Switching Light on Silicon
,
17Electro-Optic Modulator on Silicon-on-Insulator
Change in resonance obtained by injecting free
carriers into the ring resonator
?n ?ne ?nh -8.8x10-22. ?N
8.5x10-18.(?P)0.8
Simulation Results
18Scanning electron micrograph of a ring resonator
Oxide Deposition
Width 450nm
BOx 3µm
Gap 200nm
Si Substrate
Diameter 12µm
Via Hole Etching and Ion Implantation
p (B)
n (As)
BOx 3µm
Si Substrate
Contact Metallization
Microscope image of fabricated optical modulator
with electrical contacts
BOx 3µm
Si Substrate
19Summary
- Fiber - waveguide couplers 2dB/coupler,
Micrometer-long, high tolerance to misalignment - GHz 15dB all-optical and electro-optic modulators
based on high confinement