some practical issues in deep-time multiplexing
TRANSCRIPT
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2016 Photonic Doppler Velocimetry Workshop: June 6โ9, 2016
Some Practical Issues in Deep-Time Multiplexing
Michael PeรฑaDefense Experimentation and Stockpile Stewardship
National Security Technologies, LLC
This work was done by National Security Technologies, LLC, under
Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy.
DOE/NV/25946--2857
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2016 Photonic Doppler Velocimetry Workshop: June 6โ9, 2016
โบ Deep-time multiplexing
โ Conceptual design
โบ Index of refraction variations
โ Wavelength
โ Temperature
โบ State of Polarization
โ Stability
โ Control
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Outline
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Deep-Time Approach ROADDM
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
800ฮผs record at detector
= 10km SMF (50us)
16 signals fromMPDV,
2 per ITU21-35
~150km SMF
DW
DM
DW
DMNS
2x2
DW
DM
2x1 PD
80km SMF
SCOPE
8 Local Oscillators1 per ITU21-35
Corningยฎ SMF-28ยฎ Ultra
ฮฑmax โค 0.18 dB
km
Dฮป โค 18.0 ๐๐
(nmยทkm)
Neff : 1.4682
Pol. Ctrl
โบ Reconfigurable Optical Add Drop โDelayโ Module
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โข Index of Refraction, n(ฮป)
โข Phase Velocity, ๐ฃ๐๐
๐
๐๐
๐(ฮป)
โข Group Velocity, ๐ฃ๐๐๐
๐๐; ๐ฮป=
โฮป2
2๐๐๐๐๐
๐๐
๐(ฮป) 1 โฮป๐
๐๐
๐ฮป
โ1
โข Group Velocity Dispersion, GVD๐2๐
๐๐2ฮป3
2๐๐๐2
๐2๐
๐ฮป2
โข Group Delay, ๐๐ =๐ฟ
๐ฃ๐=๐๐
๐๐
๐๐
๐๐=๐ ๐๐ฟ
๐๐
๐
๐๐1 โฮป๐
๐๐
๐ฮป ๐ฟ
โข Group Delay Dispersion, GDD๐๐๐
๐๐=๐2(๐๐ฟ)
๐๐2ฮป3
2๐๐๐2
๐2๐
๐ฮป2 ๐ฟ
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Wavelength-Dependent Index of Refraction
18๐๐
๐๐ โ ๐๐ร 10[๐๐] ร 1560.61 โ 1549.32 [๐๐]
= 2.032๐๐
18๐๐
๐๐ โ ๐๐ร 150[๐๐] ร 1560.61 โ 1549.32 [๐๐]
= 30.483๐๐
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Modulation Phase Shift Dispersion Measurement
Tunable
Laser
Intensity
ModulatorPD
Sine Wave
Generator
Compare phase
DUT
fm
โ๐๐ ๐ =๐ ๐ โ ๐ ๐๐360ยฐ
1
๐๐
๐ท ๐ =1
๐ฟ
๐ โ๐๐ ๐
๐๐=
1
360ยฐ๐ฟ๐๐
๐๐ ๐
๐๐
Measurement setup for fiber chromatic dispersion
ฮฯ(ฮป) = 0.00029598ฮป2 โ 0.7348ฮป + 440.16
ฮฯ(1560.61nm) - ฮฯ(1549.32nm) = 1.97305ns
๐ทฮป =1973.05๐๐
11.29๐๐โ10๐๐= 17.476
๐๐
๐๐โ๐๐
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Temperature-Dependent Index of RefractionLUNA Technical Note EN_FY1406,
โ๐
๐=1
๐ฟ
๐๐ฟ
๐๐โ๐ +1
๐
๐๐
๐๐โ๐ = ๐ผ๐ฟ + ๐ผ๐ โ๐
ฮฑL : thermal expansion coeff ๐ผ๐ : thermo-optic coeff0.55 x 10-6 ยฐC-1 ~7.0 to 9.0 x 10-6 ยฐC-1
(7.5 x 10-6 used below)
385๐๐
โ โ 10๐๐โ 15 ๐๐๐๐๐ฆ๐ = 5.78
๐๐
โ
210๐๐
โ โ 10๐๐โ 15 ๐๐๐๐๐ฆ๐ = 3.15
๐๐
โ
Observed temps.
y=0.393x -8.644
y=0.3798x -8.769
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In situ Cross-Timing Mark
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XT-mark
XT-mark in each time window
Follow temp-time fluctuations
XT-mark inherently same ฮป as
velocity record
Single XT-mark for 16 records (only
8 shown)
Temperature fluctuations ~1โ16 ns
Temp gradients = inconsistent ๐ฟt Compounded effect deeper in time
๐=1
15
๐ฟ๐ก๐๐ฟ๐ก๐
DW
DM
DW
DM
2x1
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Static Signal Fluctuations
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โข All channels seeing same
probe
โข 30 m jumpers to firing
chamber
โข Shot-to-shot variability
~10 dB
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โบ Real single-mode fibers exhibit elliptical birefringence due to
โ Deviations of core shape from circularity
โ Lateral compression
โ Residual twist
โ Bending
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Polarization/Induced Birefringence
y
x
y
x
F
F
Core ellipticity Compression Twist Bending
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Stokes Parameters vs. 50 min
๐8
๐1
LO21
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Tau Windows 1 through 8
(1 millisecond)
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Tau Windows 9 through 16
(1 millisecond)Stressed Fiber?
Increasing variations
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Local Oscillator SOP
(1 millisecond)
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Aligning Local Oscillators with Signals
๐๐1 =๐
2๐๐2 =
5๐
3๐๐3 =
๐
3๐๐4 =
๐
3
Dot Products (Signal,LO)
๐1 = 0.3546 ๐9 = 0.8797 ITU21
๐2 = 0.4207 ๐10 = 0.3000 ITU23
๐3 = โ0.1510 ๐11 = 0.7326 ITU25
๐4 = 0.5092 ๐12 = 0.7100 ITU27
๐5 = โ0.3259 ๐13 = 0.8980 ITU29
๐6 = 0.2449 ๐14 = 0.5950 ITU31
๐7 = 0.8789 ๐15 = 0.2652 ITU33
๐8 = โ0.8642 ๐16 = 0.7807 ITU35
โ1 โค ๐๐๐๐๐๐ โ ๐ฟ๐ โค 1โ Signal โฒ Local Oscillator
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Polarization Controllers โ Fiber Squeezers (EPC-300)
Linear Horizontal
๐๐๐ข๐ก = ๐0ยฐ45ยฐ0ยฐ45ยฐ
100
Linear +45
๐๐๐ข๐ก = ๐0ยฐ45ยฐ0ยฐ45ยฐ
010
45ยฐ45ยฐ
0ยฐ0ยฐ
Right Circular
๐๐๐ข๐ก = ๐0ยฐ45ยฐ0ยฐ45ยฐ
001
โบ Not all inputs are affected equally!
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Polarization Controllers โ PolarRITE (VarRotQWP)
Linear Horizontal
๐๐๐ข๐ก = ๐๐,๐
100
Right Circular
๐๐๐ข๐ก = ๐๐,๐ยฐ
001
Linear +45
๐๐๐ข๐ก = ๐๐,๐
010
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Polarization Controllers 3-Paddle (RQW-RHW-RQW)
Linear +45
๐๐๐ข๐ก = ๐๐1,๐2,๐3
010
Linear Horizontal
๐๐๐ข๐ก = ๐๐1,๐2,๐3
100
Right Circular
๐๐๐ข๐ก = ๐๐1,๐2,๐3
001
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โบ Solution to current systems will need to be:
โ Single- or few-point solution
โ Endless tracking (i.e., no reset or operation discontinuity)
โ Feedback loop, detection and compensation
โ System time constants ~seconds
โ Dynamic excursions from experiment
โ Practical
โ Ease of use
โ Cost
โ Physical footprint
โบ Looking at all-optical solutions
โ Based on nonlinear interactions
โ Raman, four-wave mixing, SBS
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Still a work in progress
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2016 Photonic Doppler Velocimetry Workshop: June 6โ9, 2016
โบ Timing issues
โ Wavelength- and temperature-dependent Index of Refraction
โ ~ 21๐๐
โโ๐๐/ ~38
๐๐
โโ๐๐
โ In situ timing marks follow time variations
โบ State of Polarization
โ Each time window will have unique state
โ SOP distribution increases with time
โ SOP relatively stable over ~1 hr and ~100s ฮผs
โ Polarization controllers effect SOPs differently
Questions?
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Conclusion