optics vs. electronics in high-speed switching and … · optics vs. electronics in high-speed...
TRANSCRIPT
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Optics vs. electronics
in high-speed
switching and signal processing
Rod Tucker
University of Melbourne
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Take-Home Messages
• Energy is too often overlooked
• Speed is over-rated
- the “Electronic Bottleneck” is an urban myth
• Electronics is improving more rapidly than optics
- at least an order of magnitude left in Moore’s law
• Optical processing promising in simple high-speed circuits
- electronics wins as complexity increases
• Size matters
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Overview
• Key requirements on digital signal processing devices
• Comparing optical and electronic signal processing
• Energy density and circuit power consumption
• Energy and signal processing
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– Logic functionality
• AND, NAND, OR, etc.
– Cascadability
• Retain logic levels when
cascading multiple devices
– Fan-out > 2
• Device output can drive input of
at least two devices
• Typical fan-out for CMOS ~ 10
– Logic level restoration
5V
5V
00 In
Out
In Out
OutIn
In
In
Out
Out
Requirements on Digital Devices
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Digital
Optical
Circuit
Comparing Optical and Electronic Circuits
O/E
O/E
O/E
E/O
E/O
E/OOptical
Inputs
Optical
Outputs
Optical
Outputs
Optical
Inputs
• Potentially high speed
• Accepts optical inputs
• Energy consumption
• Footprint
• Energy consumption
• Footprint
• Powerful digital capabilities
• Low cost
• Slower speed
• Requires O/E, E/O, and
possibly MUX/DEMUX
• Energy consumption?
+
+
-
-
Digital
Electronic
CircuitDE
MU
X
MU
X
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Optics
Switch Fabrics Buffers
Wavelength
Demutiplexers Wavelength
Multiplexers
Fibers
Forwarding Engine
J
Switch
Fabric
O/E
Converters
Reduced bit rate (i.e. parallel processing)
Electronic (DE)MUXing in Routers
Speed (throughput) is not a limitation
Electronics
DEMUX MUX
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Energy and Digital Signal Processing
Artist’s impression of optical IC
Intel I7 chip
774 million transistors
3 GHz / 95W / 296 mm2
Photo : Intel Corporation
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Optical
Devices
Optical Signal Processing Circuit
aggregateB
Aggregate input
bit rate
supply
bit op device
aggregate
PE N E
B
Total energy per bit
processed
Device operations per bitDevice energy
per bit
supplyP Optical Output portsOptical Input ports
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Electronic
Devices
Optical Output ports
Electronic Signal Processing Circuit
Optical Input portssupplyP
aggregateB
Aggregate input
bit rate
/ / ( )O E O DE MUX
bit op device
aggregate
P PE N E
B
Total energy per bit
processed
Device operations
per bit
Device energy
per bit
MUX
MUX
MUX
DEMUX
DEMUXO/E
E/O
E/O
E/O
O/E
/ /O E OP ( )DE MUXP
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Comparing Optics and Electronics
Total energy per bit processed
/ / ( )bit op device O E O DE MUXE N E E E
bit op deviceE N E
Device energy per bit
Device Operations per bit
wavelength
converter
FEC ~ 104
~ 1
Optical Signal Processing Electronic Signal Processing
MUX
MUX
MUX
E/O
E/O
E/O
DEMUX
DEMUXO/E
O/E
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Edevice = Ei + EsupplyTotal device
switching energy
DeviceInput energy , Ei
Supply energy, Esupply
Energy in Switching Devices
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Input Energy = Switching Energy
SOAInput Output
Pump
Pin ~ 160 µW IDC = 300 mA
PDC = 600 mW
Total Switching
Energy per bit = 0.6/40x109 = 15 pJ
>103 larger
Input Energy per bit
= 160x10-6/40x109 = 4 fJ
Semiconductor
Optical Amplifier
“We demonstrate an all-optical wavelength converter at 50
Gb/s. The device uses cross-gain modulation in a
semiconductor optical amplifier. The wavelength converter
has a world record low switching energy of 4 fJ”
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Fatal flaw: total energy per bit > 10 nJ/bit
I Was Wrong
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Optical
TDM
Electronic
TDM
4 x 4 Gb/s = 16 Gb/s
1988
“The Electronic Bottleneck”
Fatal flaw: Large power dissipation
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“The Electronic Bottleneck”
DEMONSTRATION OF PHOTONIC FAST
PACKET SWITCHING AT 700 Mbit/s DATA
RATE
W. L. HA
R. M. FORTENBERRY
R. S. TUCKER
Photonics Research Laboratory
The University of Melbourne
Parkville, Victoria 3052, Australia
Fatal flaws: No optical RAM, large power dissipation
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Energy in CMOS Gates
gateC
Device energy per
transition
(per bit for NRZ)
Supply energy
(ESupply)Input energy
(Ei)
VDD
LWEI1
Wire capacitance
Cw per unit length
(ESupply)
212( )device gate w w DDE C C L V
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Electronic vs All-Optical Signal Processing
10-20
10-19
10-18
10-17
10-16
10-15
10-14
2000 2010 2020
9065
4532
22
130
18
10-13
10-12
10-11
1970 1980 1990
12-mm
PMOS
Sw
itch
ing
en
erg
y E
devic
e,
J
Year
11
Feature
size in nm
CMOS gate
energy
Total CMOS energy
including wires
45
11
2232
10-10
2030
All-optical Devices
Si NanowirePPLNSOA
HNLF
Sources: ITRS ’97-’09 Roadmaps; Hinton et al., JSTQE 2008;
Möller; OFC 2010, Tucker, JSTQE, 2010
SiGe?
InP HBT E(DE)MUX
EO/E/O
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Comparing Optics and Electronics
Total energy per bit processed
/ / ( )bit op device O E O DE MUXE N E E E bit op deviceE N E
Device energy per bit
Device Operations per bit
Optical Signal Processing Electronic Signal Processing
MUX
MUX
MUX
E/O
E/O
E/O
DEMUX
DEMUXO/E
O/E
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Electronic vs Optical Signal Processing
Year
Nonlinear optical devices
Sources: ITRS ’97-’09 Roadmaps; Hinton et al., JSTQE 2008;
Möller; OFC 2010, Tucker, JSTQE, 2010
10-16
10-15
10-14
2000 2010 2020
10-13
10-12
10-11
1970 1980 1990
Sw
itch
ing
en
erg
y E
de
vic
e,
J EO/E/O
E(DE)MUX
10-10
2030
xx
x
x
x
xx2 PJ
x 20 fJTotal CMOS energy
including wires
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Energy and Integrated Circuits
Number of operations per bit, Nop
10-13
1 10 100 1,000
10-12
10-11
10-10
10-9
Tota
l energ
y p
er
bit p
rocessed ,
E
bit
(J)
Edevice = 2 pJ
Edevice = 20 fJ
O/E/O + (DE)MUX
10,000
Optical
Electronic
(2020)
Electronic
(2010)
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Chip Energy Density
Device
Pitch, d
Optical or
electronic chip
Psupply
Optical or
electronic device
Tucker, PTL 2008
Electronic IC: Energy consumption dominated by CV2 energy in interconnects
Optical IC: Energy consumption dominated by supply energy
PD = 100 W/cm2,
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Optical and Electronic Integrated Circuits
Source: Tucker, PTL 2008
Energ
y p
er
Bit,
Esu
pp
ly (J)
10-17
10-16
10-15
10-14
10-610-7 10-5 10-4
10-13
10-3 10-2
10-12
10-11
Device Pitch, d (m)
Nonlinear Optical DevicesActivity factor
2 pJ/b
20 fJ/b
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Optical and Electronic Moore’s LawN
um
ber
of
De
vic
es p
er
1-c
m2
Chip
Year
1970 1980 1990 2000 2010
1010
108
106
104
102
1.9 Billion (Intel SRAM)
2020
11-nm CMOS
energy limit
Infinera (~ 102)
Nonlinear
optics energy
limit: 1 GHz
1 GHz
100 GHz
Nonlinear
optics energy
limit:100 GHz
20 fJ/b
20 fJ/b
2 pJ/b
2 pJ/b
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Source: Hinton, Raskutti & Tucker, JSTQE 2008
10-8
Sw
itchin
g E
nerg
y/b
it (
J)
Device Size (m)
104102110-210-410-610-8
10-10
10-12
10-14
10-16CMOS (ITRS)
Nonlinear Fibre
Semiconductor
Optical Amplifier
Si nanowire (FWM)
Periodically Polled
Lithium Niobate
Device Switching Energy and Size
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Take-Home Messages
• Energy is too often overlooked
• Speed is over-rated
- the “Electronic Bottleneck” is an urban myth
• Electronics is improving more rapidly than optics
- at least an order of magnitude left in Moore’s law
• Optical processing promising in simple high-speed circuits
- electronics wins as complexity increases
• Size matters
![Page 26: Optics vs. electronics in high-speed switching and … · Optics vs. electronics in high-speed switching and signal processing ... Nonlinear optics energy limit: 1 GHz 1 GHz ... Nonlinear](https://reader031.vdocuments.us/reader031/viewer/2022021802/5b8682737f8b9af12d8d288e/html5/thumbnails/26.jpg)
Optical and Electronic Integrated Circuits
Artist’s impression of optical IC
operating at excessive power density