Silicon Optical Modulators硅基光调制器

Switching test on psuedo-random time signal.
Conclusion
?MOS modulator has poor loss figures and
still an order of magnitude slower than commercial modulators. Intel argues these can both be theoretically fixed by decreasing the size of the device and using Si in the guide region instead of poly (still integrable?).
p-i-n Si Optical Modulators 3/4
? n = ? ne + ? nh = -[8.8 x 10-22(? Ne) + 8.5 x 10-18(? Nh)0.8] ?? = ?? e + ?? h = 8.5 x 10-18 (? Ne) + 6.0 x 10-18(? Nh)
Silicon Optical Modulators
Recent developments in fabrication of High Speed Modulators
J ee290f
Outline
?Motivation ?Png, Reed, et al. work from Surrey.
?Shows basic principle and gives one of the two major design types
?P-i-n modulator is still being fabricated
and depends on its optimal design for the high values achieved, so potentially success or failure from fabrication runs.
can be optimized to 1.3GHz and a 180? at .7 mA of current.
?However, performance is very
dependant on doping profile and a critical dimensions are not very tolerant.
?As of late 2003, fabrication is
underway.
MOS Si Optical Modulators 1/4
? Still uses the plasma
dispersion effect, but implements a MOS capacitor to induce change in free carrier density instead of a p-i-n device.
?Intel device
?History making device, designed and fabricated in alternate major design type.
?Conclusions
Fra Baidu bibliotek
Motivation
?Very clear: Si modulators means
CMOS integration and using all our experience in silicon micromachining.
?Again designed for
single mode 1.55? m.
MOS Si Optical Modulators 2/4
Apply VD to poly. Charge accumulation on both sides of gate oxide.
? Ne
=
? N =[
h
?/etoxt]*(VD – VFB)
? ne = -8.8 x 10-22? Ne
? nh = -8.5 x 10-18(? Nh)0.8
?? = (2?/? )? neffL
MOS Si Optical Modulators 3/4
?Implemented
phase shifter in both arms of a MZI.
?For VD = 7.7V →
16dB total switch.
?Loss is the big key:
~15.3dB insertion loss (~4.3dB from coupling & ~6.7dB from poly guides).
MOS Si Optical Modulators 4/4
See 3dB roll off at >1GHz from MOS cap.
?Unfortunately, prior to 2003 the
fastest Si optical modulator was ~20MHz (Lithium Niobate modulators are ~10GHz).
p-i-n Si Optical Modulators 1/4
?Follows the work presented by Png, Reed,
et al from Surrey University (UK).
p-i-n Si Optical Modulators 2/4
VD is applied to Anode vs. Cathode. → forward biased p-i-n junction. → e and holes injected into guiding region → changes refractive index
From R.A. Soref & B. R. Bennett “Electrooptical Effects in Silicon” Jour. Of Quan. Elec. 1987.
p-i-n Si Optical Modulators 4/4
?Simulation results show modulation