Download - Two-dimensional fiber array with integrated topology for short-distance optical interconnections
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Two-dimensional fiber array Two-dimensional fiber array with integrated topologywith integrated topologyfor short-distance optical interconnectionsfor short-distance optical interconnections
Makoto Naruse1),2), Alvaro Cassinelli3), and Masatoshi Ishikawa3)
1: Ultrafast Photonic Network GroupCommunications Research Laboratory , Japan
E-mail: [email protected]
2: Japan Science and Technology Corporation (JST), PRESTO
3: Dept. Information Physics and Computing, University of Tokyo
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Contents
1. Interconnection fabric
2. Wave-guide-base, direct implementation of interconnection topology
3. Interconnection decomposition
4. Experimental fabrication
5. Summary and future plans
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Optical Interconnection fabric / switching fabric
LSILSI
LSILSI
LSI
LSILSI
LSI
Optical Interconnection fabric / Switching fabric
Inter Chip, Inter-boardOptical interconnection
Optical interconnection
Multistage architecture
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Multistage architecture
…
…
All optical
Optoelectronic
An example: Omega network
Inp
ut
Ou
tpu
t
OE
Computation
EO Optical interconnect
Optical interconnect
w/o OEO
Regularly interconnected multistage architecture
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Wave-guide-base, direct implementation of interconnection topology
…
…
OE
Computation
EO Optical interconnect
Optical interconnect
w/o OEO
• Two-dimensional fiber array
Configure the interconnection topology directly by positioning the input and output end of the wave-guides
Input
Output
All optical
Optoelectronic
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Design considerations
• Two-dimensional (2D) parallelism • Focus on Permutation network (such as perfect shuffle)• Scalability• Module reusability (Permutation reusability)
• Alignment difficulty: Both input and output end• Theoretically more volume efficient than free-space equivalent
Other remarks
Out of scope of this paper
Y.Li, et. al., “Volume-consumption comparisons of free-space and guided-wave optical interconnections”, Appl.Opt. 39 (2000), 1815
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Example1: Omega networkIn
pu
t
Ou
tpu
t
0
1
2
3
4
5
6
7
8
9
10
11
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• Messy topology
• Poor scalability
• Poor reusability
Permutation=Perfect shuffle
2D direct implementation
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Example 2:Indirect Binary n-Cube Network
Permutation=Butterfly and perfect shuffle
Several kinds of different interconnection topology are used
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Interesting fact
Perfect shuffle and butterfly permutation can be made out of the following three types of elemental permutations: Row, Column, and Diagonal permutations
Column permutationRow permutation Diagonal permutation
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Before decomposition
Direct implementation
0
1
2
3
4
5
6
7
8
9
10
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0123456789
101112131415
Node assignment:Scan mapping
Perfect shuffle
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Interconnection decomposition
Row permutation
Column permutation
Diagonal permutationDecompose
0123456789
101112131415 1
2
6
14
0123456789
101112131415
Perfect shuffle
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Interconnection decomposition
Column permutation
Column permutation
Diagonal permutation
0123456789
101112131415
Decompose
3
10
10
3
0123456789
101112131415
Butterfly
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shuffle shuffle shuffleshuffle
Processor arrays
(exchange switches and more)
Row permutation
90º
Overall Omega Network
Column permutation
Diagonal permutation
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(2) (3) (4) -1(4)
Processor arrays
(exchange switches and more)
Row permutation
90º
Column permutation
Diagonal permutation
Overall Indirect Binary n-Cube Network
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Two holder prototypes: Zirconium, SiO2
Pitch: 250±5 m
Multimode graded index fibers: NA=0.21(core 50m, cladding 126m)
Transmission loss: 3dB/km
Length: 30 cm
Prototype fiber module: Preliminary 4x4 array
3 mm
2 mm
5 mm
Embedded interconnection topology
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Pitch uniformity
0
2
4
6
8
10
12
14
16
244 246 248 250 252 254 256
Zirconium
Pitch (m)
Num
ber
of li
nk
245m-255mAve. 250mStd deviation 2.0m
246m-254mAve. 250mStd deviation 1.5m
SiO2
Pitch(250m)
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Input Output (CCD image)
No relay optics
Interconnection example
VCSEL arrayFiber module input
Input
Output
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x 50 m
0
0.05
0.1
0.15
0.2
0.25
-105 -90 -75 -60 -45 -30 -15 0 15 30 45 60 75
X (microns)
Exi
t p
ow
er (
a.u
)
x
Alignment tolerances(half peak power)
y 70 m
Transmission efficiency / Alignment tolerance
Transmission efficiency
Max. transmittance 38.45%
0
5
10
15
20
25
30
35
40
45
6 7 8 9 10 11 12 13
VCSEL driving current (mA)
Tra
nsm
itta
nce
(%
)
38.45
9.5
LED regime
LASER regime
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Summary and future plans
• Wave-guide-base, direct implementation of 2D parallel interconnection topology
• Interconnection decomposition for scalability and reusability
• 2D fiber array with interconnection topology was demonstrated
Future plan: • Theoretical foundation for interconnection
decomposition and total system design• Higher-density 2D interconnect• System demonstration