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Gilles Rasigade1, Delphine Marris-Morini1, Laurent Vivien1, Eric Cassan1, Paul Crozat1Philippe Lyan2, Pierrette Rivalin2, Jean-Marc Fédéli2
1 Institut d'Electronique Fondamentale, CNRS UMR 8622, Université Paris-Sud - CNRS, 91405 Orsay Cedex, FRANCE2 CEA LETI, Minatec, 17 rue des Martyrs, 38054 Grenoble Cedex 9, FRANCE
HIGH SPEED SILICON OPTICAL MODULATOR
Electrical signal Optical signal
ACTIVE REGIONPIN modulator design ISE electrical simulations
Holes density ∆n(V)
0 V
1 V
2 V
3 V
4 V
2.0x10-4
1.5
1.0
0.5
0.0
∆nef
f
543210Voltage (V)
Effective index variation
Phosphorus doped(~1.1018 cm-3)
Boron doped(~1.1018 cm-3)
Boron doped(~5.1017 cm-3)
=0
=2neff L
L
Sin-dopedp-doped activep-dopedmetal
Low capacitance (0.3 fF/µm)
Reduced and control optical loss
No electrode loss contribution
Simple fabrication process
Good overlap factor
Fabrication
Numerical resolution of Poisson, carrier continuity, and drift-diffusion equations
ISE
Soref and Bennett1
Mode solver
N x , y P x , y
n x , y x , y
neffeff
SPLITTER
IinIout,1Iout,2
< 2 µmLow wavelength dependent transmission and ultra-compact.
EXPERIMENTAL RESULTS
50 Ω
DC+RF
50 Ω
DC+RF
Current < 1 µA Insertion loss of 5 dB Contrast up to 15 dB VπLπ of 5 V.cm
Asymetric DC Mach-Zehnder transmission
RF optical response
-3 dB cut-off frequency of 15 GHz
=
-6
-5
-4
-3
-2
-1
0
1
Nor
mal
ized
opt
ical
resp
onse
(dB
)
0.12 3 4 5 6 7 8 9
12 3 4 5 6 7 8 9
102 3
Frequency (GHz)
λ = 1557nm - polarization TE - VDC = 1V
-3dB
15GHz
CONCLUSIONExperimental results
Further improvements (→ 40 Gbit/s)Increase of the modulation efficiency to decrease the footprint.Optimization of the RF coplanar electrodes to improve the electrical signal propagation.
Contrast : 15 dBInsertion loss : 5 dB-3 dB cut-off frequency : 15 GHz
pHotonics ELectronics functional Integrations On CMOS
European Community’s Seventh Framework Program (FP7)
INTRODUCTIONApplications Photonic benefits Silicon opportunity
Optical interconnects TelecommunicationsLow signal distortion
Low propagation loss
Wavelength multiplexing (WDM)
Mature technology
High production volume
High density integration
Electro-refraction methods
All-silicon high speed optical link
Electro-refraction
nV neff V V interferometer I V
Variation of carrier concentration ∆N, ∆P
Accumulation Injection Depletion
Gilles Rasigade | CMOS Photonics Winter School | March 20091. R. A. Soref, B. R. Bennett, “Electrooptical effects in silicon”, IEEE Journal of Quantum Electronics, QE-23 (1), 123-129 (1987).