Fully reconfigurable waveguide Bragg gratings for ...jpyao/mprg/reprints/OFC2019-W3BI...Able to...
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OFC2019
OFC2019
March 3-7, 2019, San Diego
Fully reconfigurable waveguide Bragg gratings for programmable photonic
signal processing
Jianping Yao and Weifeng Zhang
Microwave Photonics Research LaboratorySchool of Electrical Engineering and Computer Science
University of Ottawa
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OFC2019
Photonic Integrated Circuits - Material Systems Silicon photonic gratings– Chirped Bragg gratings for RF generation– Phase-shifted gratings for temporal differentiation– Electrically tunable Fabry–Perot Bragg grating for signal processing– Fully reconfigurable waveguide Bragg gratings for programmable
photonic signal processing– Electrically programmable equivalent-phase-shifted waveguide Bragg
gratings for multichannel signal processingConclusion
Outline
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OFC2019
Three material systems: 1) Indium Phosphide (InP) 2) Silicon Nitride (Si3N4)3) Silicon on Insulator (SOI)
1) InP: Able to monolithically integrate both active and passive photonic
components High loss, and large sizeDifficulty to integrate with electronics
Material systems
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OFC2019Material systems2) Si3N4: Very low loss, <0.2 dB/cm No active components such as light sources, modulators, amplifiers and
photodetectors can be supported, thus full monolithic integration is hard to achieve
3) SiP: A technology that allows optical devices to be made economically using the standard
and well-developed CMOS fabrication processMost of the optical components, both passive and active, can be fabricated The key advantages include much smaller footprint, low loss, and simple
fabrication process and can be integrated with electronics (analog and dgital) No optical amplification and light emission
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OFC2019
Photonic Integrated Circuits - Material Systems Silicon photonic gratings– Chirped Bragg gratings for RF generation– Phase-shifted gratings for temporal differentiation– Electrically tunable Fabry-Perot Bragg grating for signal processing– Fully reconfigurable waveguide Bragg grating for programmable
photonic signal processing– Electrically programmable equivalent-phase-shifted waveguide Bragg
grating for multichannel signal processingConclusion
Outline
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OFC2019Chirped RF waveform generation
Autocorrelation(Matched Filtering)
Autocorrelation(Matched Filtering)
Chirp-free pulse
Chirped pulse
Chirped microwave pulse can be compressed by matched filtering, widely employed in Radar systems.
-1500 0 15000
1
Time (ps)
Norm
. Apm
.
-500 0 500-1
0
1
-500 0 500-1
0
1
Time (ps)
Norm
. Apm
.
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OFC2019Photonic microwave waveform generation based on spectral shaping and frequency-to-time mapping
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OFC2019
• Frequency-to-time mapping
Wavelength-to-time mapping, namely dispersive Fourier transformation, is a fast and effective way to measure optical spectrum in the time domain.
Dispersive Elementt
ω
t( )g t
( )y t
( )G ω
( ) tGω
ω=Φ
≈
Photonic microwave waveform generation based on spectral shaping and frequency-to-time mapping
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OFC2019
λ
Input Output
FSR = 1 / τ
Offset waveguideLCBG1
LCBG2
λ
τ
On-chip spectral shaper incorporating linearly chirped waveguide Bragg gratings
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OFC2019On-chip spectral shaper incorporating linearly chirped waveguide Bragg gratings
Perspective view of the proposed on-chip silicon-basedoptical spectral shaper. (Inset: (Left) Wire waveguide and(Right) Rib waveguide)
λ
λSIlicaSIlicon
SiO2
W
Si
SiO2
H1SiH2
SiO2
SiW
Si
SiO2
H
W. Zhang and J. P. Yao, J. Lightw. Technol. 33, 5047-5054 (2015).
(a) Schematic layout of the designed on-chip spectralshaper; (b) Image of the fabricated spectral shapercaptured by a microscope camera.
(b)
Input Grating Coupler
Adiabatic S- Bend
Linearly Chirped Grating
Output Grating Coupler Compact
Y-Branch
Taper I Taper II
Offset Waveguide
linearly Chirped Grating
(a)
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OFC2019
SIlicaSIlicon
1.60
1.75
1.90
-20
-10
0
Refle
ctio
n (d
B)
Grou
p De
lay
(ns)
-20
-10
0
1.50
1.65
1.80
1.53 1.545 1.56Wavelength (um)
1.60
1.75
1.90
-20
-10
0
(a)
(b)
(c)
Perspective view of the proposed LC-WBG. (Inset: Simulatedfundamental TE mode profile of the rib waveguide with the ribwidth of 500 nm (left) and 650 nm (right)).
Measured spectral and group delayresponses of the LC-WBG with the ribwidth increasing from 500 nm to (a) 550nm, (b) 600 nm and (c) 650 nm alongthe gratings.
On-chip spectral shaper incorporating linearly chirped waveguide Bragg gratings
2B effnλ = Λ
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OFC2019Experimental Results
1.53 1.538 1.546
-50
-35
-20
Wavelength (um)
Pow
er (d
Bm)
1.53 1.538 1.546-50
-35
-20
Wavelength (um)
OSC
ISOOn-Chip
Spectral ShaperPD
EDFA
TMLLED
FA
PCDCF
Experimental setup. TMML: tunable mode lock laser. ISO: Isolator; EDFA: erbium-doped fiberamplifier. PC: polarization controller. DCF: dispersion compensation fiber. PD: photodetector.OSC: oscilloscope.
Measured spectral response of anon-chip spectral shaper when thelength of the offset waveguide is(left) zero and (right) the length ofthe LC-WBG.
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OFC2019Experimental Results
-400 -200 0 200 4000
0.5
1
Time (ps)
Nor
mal
ized
Ampl
itude
4 10 160
1
2
Ampl
itude
(mA)
Time (ns)
Time (ns)
Inst
anta
neou
s Fr
eque
ncy
(GHz
)
4 10 16
15
30
00.1
0.5
0.9
(c)
(a)
(b)
Experimental result: (a) the generated LCMW; (b) experimentalspectrogram curve and numerical instantaneous frequency of thegenerated LCMW, and (c) compressed pulse by autocorrelation whenthe length of the offset waveguide equates to zero.
-400 -200 0 200 4000
1
Time (ps)
0.5
Nor
mal
ized
Ampl
itude
5 15 25 350.2
0.8
1.4
Ampl
itude
(mA)
Time (ns)
Time (ns)5 15 25 35
10
20
30
Inst
anta
neou
s Fr
eque
ncy
(GHz
)
0.1
0.5
0.9
(a)
(b)
(c)
Experimental result: (a) the generated LCMW; (b) experimentalspectrogram curve and numerical instantaneous frequency of thegenerated LCMW, and (c) compressed pulse by autocorrelation whenthe length of the offset waveguide equates to the length of LC-WBG.
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OFC2019
Photonic Integrated Circuits - Material Systems Silicon photonic gratings– Chirped Bragg gratings for RF generation– Phase-shifted gratings for temporal differentiation– Electrically tunable Fabry–Perot Bragg grating for signal processing– Fully reconfigurable waveguide Bragg grating for programmable
photonic signal processing– Electrically programmable equivalent-phase-shifted waveguide Bragg
grating for multichannel signal processingConclusion
Outline
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OFC2019Photonic temporal differentiator
The transfer function:
1556.5 1557 1557.5 15580
0.2
0.4
0.6
0.8
1
Wavelength (nm)
Mag
nitu
de
(a)
π
1556.5 1557 1557.5 1558-4
-3.5
-3
-2.5
-2
-1.5
-1
Wavelength (nm)
Phas
e (
rad)
(b)
Magnitude and phase response of a differentiator.
( ) ( )n
n
d x ty t
dt=A nth order temporal differentiator:
Applications: phase to intensity conversion in an optical phase-modulated system.
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OFC2019
(b)
(c) (d)
Phase-shifted Grating on Ridge Waveguide
Taper Waveguide
(a)
Strip WaveguideGrating Coupler
Input Grating coupler
Phase-Shifted Bragg Grating
Output Grating coupler
Taper Taper
W. Zhang, W. Li, and J. P. Yao, IEEE Photon. Technol. Lett. 26, 2383-2386 (2014).
Configuration of the phase-shifted Bragg grating (PSBG) in a silicon-on-insulator ridge waveguide.
(a) Schematic layout. (b) Image of the fabricateddevice. (c) Image of the grating couplers and the stripwaveguides. (d) Image of the taper waveguides for thetransition between the strip waveguides and ridgewaveguides.
Photonic microwave temporal differentiator using an integrated phase-shifted Bragg grating
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OFC2019
1556.5 1558.1
-50
-46
-42
-38
-34
wavelength (nm)
Pow
er (d
Bm)
ReflectionTransmission
1557.3 1556.8 1557.1 1557.40
0.5
1
wavelength (nm)
Refle
ctio
n (a
.u.)
-1
0
1
2
Phas
e (r
ad)
-2
0.3 nm
(Left) Measured reflection and transmission spectral responses of the fabricated PSBGon a ridge waveguide with a designed corrugation width of 125 nm. (Right) Zoom-inview of the reflection notch and its phase response.
Experimental Results
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OFC2019
(Left) An input Gaussian pulse with an FWHM of 25 ps, and (Right)the temporally differentiated pulses by simulation and experiment.
MLL
Wave-Shaper Polarizor PD
OSCPhase-Shifted Bragg
Grating on SOI
PCEDFA EDFA
Experimental setup. MML: mode lock laser. EDFA: erbium-doped fiber amplifier. PC: polarization controller. PD: photodetector. OSC: oscilloscope.
Experimental Results
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OFC2019
Photonic Integrated Circuits - Material Systems Silicon photonic gratings– Chirped Bragg gratings for RF generation– Phase-shifted gratings for temporal differentiation– Electrically tunable Fabry–Perot Bragg grating for signal processing– Fully reconfigurable waveguide Bragg grating for programmable
photonic signal processing– Electrically programmable equivalent-phase-shifted waveguide Bragg
grating for multichannel signal processingConclusion
Outline
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OFC2019
W. Zhang, N. Ehteshami, W. Liu, and J. Yao, Opt. Lett. 40, 3153–3156 (2015)
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OFC2019Silicon-based on-chip electrically tunable phase-shifted waveguide Bragg grating
1540.5 1541.5 1542.5
-40
-30
-20
Wavelength (nm)
Pow
er (d
Bm)
ReflectionTransmission
ReflectionTransmission
1540.5 1541.5 1542.5
-40
-30
-20
Wavelength (nm)
Pow
er (d
Bm)
ReflectionTransmission
Measured spectra when a zero bias voltage is applied. Thenotch in the reflection band has a 3-dB bandwidth of 46pm with a Q-factor of 33,500, and an extinction ratio of16.4 dB.
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OFC2019Silicon-based on-chip electrically tunable phase-shifted waveguide Bragg grating
1540.5 1541.5 1542.5
-40
-30
-20
Wavelength (nm)
Pow
er (d
Bm)
V=-0V=-0.8V=-0.85V=-0.88V=-0.9V=-0.92
V=-0.95V=-0.95
V=-0V=-0.8V=-0.85V=-0.88V=-0.9V=-0.92
V=-0.95V=-0.95
1540.5 1541.5 1542.5-40
-30
-20
Wavelength (nm)
Pow
er (d
Bm)
1541.6 1541.9-40
-30
-20
V=0V=3.5V=8V=13V=16
Reverse Bias
Forward Bias
Blue-shift of the transmission spectrum when the PN junction is forward biased.
Red-shift of the transmission spectrum when the PN junction is reverse biased.
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OFC2019Silicon-based on-chip electrically tunable phase-shifted waveguide Bragg grating
The resonance wavelength is shifted. A fixedresonance wavelength with a tunable phase-shift isdesired.
By incorporating multi-phase-shifted blocks in thePS-WBG, a delay line with a wider bandwidthcould be realized .
Application 1: Tunable fractional-order photonic temporal differentiator
Application 2: Tunable optical delay line
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OFC2019
Photonic Integrated Circuits - Material Systems Silicon photonic gratings– Chirped Bragg gratings for RF generation– Phase-shifted gratings for temporal differentiation– Electrically tunable Fabry–Perot Bragg grating for signal processing– Fully reconfigurable waveguide Bragg grating for programmable
photonic signal processing– Electrically programmable equivalent-phase-shifted waveguide Bragg
grating for multichannel signal processingConclusion
Outline
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OFC2019
W. Zhang and J. P. Yao, Nature Comm., 9, 1396 (2018)
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OFC2019
Wafer Grating Doping Independent Electrodes
Voltage Control
Programmable grating
Grating design
n1
n2
V1 V2 V3 V4 V5 V6 V7
n1
n2
V1 V2 V3 V4 V5 V6 V7
n1
n2
V1 V2 V3 V4 V5 V6 V7
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OFC2019Grating design
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OFC2019Measured reflection and transmissionspectrums.
(a) Reflection and transmission spectrum ofthe fabricated grating in the static state;(b) Notch wavelength shift when the biasvoltages applied to the left and right sub-gratings vary synchronously;(c) Extinction ratio tuning while the notchwavelength is kept unchanged;(d) Reflection and transmission spectrumswhen the grating is reconfigured to be auniform grating;(e) Wavelength tuning of the uniform grating;(f) Reflection and transmission spectrumswhen the device is reconfigured to be auniform grating by increasing the cavity loss;(g) Reflection and transmission spectrumswhen the device is reconfigured to be twoindependent uniform sub-gratings; and(h) Reflection and transmission spectrumswhen the device is reconfigured to be achirped grating.
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OFC2019Programmable microwave signal processor
RF Input
PDPC1PC2
Silicon substrate
10100...
DC SourcesMZM
Power Meter
EDFATLS
RF Input
PDPC1PC2
Silicon substrate
10100...
DC SourcesMZM
Power Meter
EDFATLS
The experimental set-up consists of a tunable laser source (TLS), a polarization controller (PC), aMach-Zehnder modulator (MZM), an erbium-doped fiber amplifier (EDFA) and a photodetector (PD).
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OFC2019Experimental demonstration
W. Zhang and J. P. Yao, Nature Comm. 9, 1396 (2018)
0 1000 20000
0.5
1Po
wer
(dBm
)
Time (ps)
n = 0.143
0 1000 20000
0.5
1
Pow
er (d
Bm)
Time (ps)
0
0.5
1
Pow
er (d
Bm)
0
0.5
1
Pow
er (d
Bm)
b c
e
-4 -2 +2 +4-0.8
-0.4
0
0.4
0.8
0Frequency (GHz)
Phas
e (r
ad)
1.7
-0.825
-2.06
V1 V2 V3+200
0 0 0+20 0 -0.825+20 0
-2.30 +11+20
V
0 -2.63 0
a
-4 -2 +2 +4-0.8
-0.4
0
0.4
0.8
0Frequency (GHz)
Phas
e (r
ad)
1.7
-0.825
-2.06
V1 V2 V3+200
0 0 0+20 0 -0.825+20 0
-2.30 +11+20
V
0 -2.63 0
a
0 1000 2000Time (ps)
n = 0.229d
0 1000 2000Time (ps)
n = 0.541
Function 1: Photonic temporal differentiation Function 2: Microwave time delay
Function 3: Microwave frequency identification
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OFC2019
Photonic Integrated Circuits - Material Systems Silicon photonic gratings– Chirped Bragg gratings for RF generation– Phase-shifted gratings for temporal differentiation– Electrically tunable Fabry-Perot Bragg grating for signal processing– Fully reconfigurable waveguide Bragg grating for programmable
photonic signal processing– Electrically programmable equivalent-phase-shifted waveguide Bragg
grating for multichannel signal processingConclusion
Outline
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OFC2019Equivalent-phase-shifted Bragg grating
Conventional phase-shifted waveguide Bragg grating
grating pitch phase-shifted block
Equivalent-phase-shifted (EPS) waveguide Bragg grating
Uniform grating
Sampling function
EPS grating
P+∆Psampling period P
Feature size three orders of magnitude larger easy to fabricate
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OFC2019Programmable EPS grating design
W. Zhang and J. P. Yao, J. Lightw. Technol., 37, 314-322 (2019).
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OFC2019Programmable EPS grating design
Wafer Grating Doping Independent Electrodes
Voltage Control
Programmable EPS Grating
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OFC2019Programmable EPS grating design
36
OFC2019Performance evaluation: static state
1525 1530 1535 1540 1545 1550 1555 1560-60
-50
-40
-30
-20
Optic
al po
wer (
dBm
)
Transmisson Reflection(a)
Wavelength (nm)1546 1548 1550 1552 1554 1556 1558 1560
-60
-50
-40
-30
-20
Optic
al po
wer (
dBm
)
Transmisson Reflection
+11+9+7+5+1 +3
(c) 2.4 nm
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OFC2019Performance evaluation:independent test
1548.9 1549.1 1549.3 1549.5Wavelength(nm)
-36
-32
-28
-24 Reverse biasForward
bias
Opt
ical
pow
er
(dBm
)
-19 V-12 V-8 V-4 V
0 V0.7 V0.9 V1.0 V
1548.9 1549.1 1549.3 1549.5Wavelength(nm)
-36
-30
-24 Reverse biasForward
bias
-19 V-12 V-8 V-4 V
0 V0.7 V0.9 V1.0 VO
ptic
al p
ower
(d
Bm)
Applying and tuning a bias voltage to the PN junctions in the on-modulation grating sections
Applying and tuning a bias voltage to the PN junctions in the off-modulation grating sections
+3rd channel spectral response tuning
+3rd channel spectral response tuning
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OFC2019Performance evaluation: programmability
1548.9 1549.1 1549.3 1549.5Wavelength(nm)
-38
-34
-30
-26
-22
Opt
ical
pow
er (d
Bm) Reverse
biasForward
bias
(a) -19 V-15 V-12 V-8 V-4 V0V
0.7 V0.9 V1.0 V
1549.08 1549.16 1549.24
Wavelength (nm)
-33
-30
-27
-0.6
-0.2
0.2
0.6
1549.08 1549.16 1549.24
Opt
ical P
ower
(dBm
)Ph
ase
(rad
)
0 V 0 V-7.0 V 0.86 V
-11.5 V 0.92 V-19 V 1.02 V
on- off-
0 V 0 V-7.0 V 0.86 V
-11.5 V 0.92 V-19 V 1.02 V
on- off-
1. The two bias voltages are simultaneously and synchronously changed from −19 to +1 V.
2. Tuning the extinction ratio whilethe 3rd channel notch wavelength ismaintained unchanged for differentbias voltages.
+3rd channel spectral response tuning
Extinction ratiochange:from 6.4 to 4.5
Phase jump change:from 1.0 to 0.48
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OFC2019Multichannel signal processing: temporal differentiation
-800 -400 0 400 800Time (ps)
0
0.4
0.8
1.2
Inte
nsity
(n.u
.)
Exp.Theo.
(b)
-800 -400 0 400 800Time (ps)
0
0.4
0.8
1.2
Inte
nsity
(n.u
.)Exp.
Theo.(a)
A multichannel temporal differentiator with a channel spacing of 2.4 nm isexperimentally demonstrated. The figure shows the measured temporallydifferentiated pulses corresponding to a differentiation order of (a) 0.53 at the +5th
channel, and (b) 0.74 at the +7th channel.
Differentiation order: 0.53at the +5th
channel
Differentiation order: 0.74at the +7th
channel
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OFC2019
Thank you
Silicon photonics is a solution for ultra-fast optical signal processing withreduce the size and cost.
By electrical tuning, a silicon photonic grating can be made programmableand reconfigurable for various optical or microwave signal processing
Heterogeneous integration may be needed to produce laser sources andoptical amplifiers using III-V materials, to achieve monolithic photonicintegrated signal processing systems (system on chip) - a key challenge forwide applications of silicon photonics.
Conclusion
41
OFC2019Acknowledgments
CMC Microsystems
NSERC Si-EPIC program