Chalcogenide Glasses for Integrated Photonics · 2020-02-05 · Juejun (JJ) Hu PMAT hujuejun@mit.edu As S Se As 2 Ch 3 Glass Crystal Property Range Refractive index 2.3 –2.8 Nonlinear
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Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Chalcogenide Glasses for Integrated Photonics
Juejun (JJ) Hu
Materials Science & Engineering, MIT
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Materials
Devices
Systems
Infrared glass
Phase change
materials
Infrared gas
sensorsTunable
metasurfaces
2D material
integration
Optical
isolator
Micro-CPV Board-level
interconnect
Mini-
spectrometer
Research @ PMAT
Flexible
photonics
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Tian Gu
Hongtao Lin
Lan Li
Derek Kita
Jerome Michon
Qingyang Du
Sarah Geiger
Gufan Yin
Duanhui Li
Skylar Deckoff-Jones
Haya Alhummiany
Yifei Zhang
Hanyu Zheng
Huikai Zhong
Roger Fang
PMAT @
Funding support
Collaborators
Kathleen Richardson
Nanshu Lu
Jing Kong
Daniel Hewak
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
2-D materials
Monolithic photonic integration on 2-D materials
Flexible planar photonics
Integration with nanomembranes and elastomers
Glass photonic integration
ChGs are uniquely poised for multi-material integration
Introduction
Chalcogenides (ChGs): an emerging optical material
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Introduction
Chalcogenides (ChGs): an emerging optical material
2-D materials
Monolithic photonic integration on 2-D materials
Flexible planar photonics
Integration with nanomembranes and elastomers
Glass photonic integration
ChGs are uniquely poised for multi-material integration
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Amorphous compounds ofchalcogens (S, Se and Te) covalently bonded to other elements
Adv. Mater. 25 (2013): 3050-3054; Opt. Express 18 (2010): 26720-26727.
ChG lenses ChG fibers ChG Microspheres ChG Metaswitch
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Wide IR transparency makes ChGs ideal materials for
infrared sensing
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
ChG mid-infrared photonics
Sci. Tech. Adv. Mater. 15, 014603 (2014)
OE 21, 29927 (2013); OE 23, 19969 (2015)
Opt. Mater. Express 4, 1617 (2014)
Opt. Lett. 35, 3324 (2010)
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
As
S Se
As2Ch3
Glass
Crystal
Property Range
Refractive
index2.3 – 2.8
Nonlinear
index
0.2 – 1.2
[10-17 m2/W]
Optical
band gap
1.6 – 2.3
[eV]
Glass
transition
80 – 220
[°C]
M. A. Popescu, Non-crystalline
chalcogenides, Springer (2001).
Index-matching, insulating
optical adhesive in stacked
solar cells
Nat. Mater. 13, 593 (2014)
ChG properties can be tuned over a wide range
via composition engineering
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
ChGs exhibit large optical Kerr nonlinearity
MaterialNonlinear index
n2 (10-20 m2/W)
TPA
a2 (10-12 m/W)
FOM
( n2/a2l )
Silica (SiO2) 2.2 ‒ ‒
c-Si 440 8.4 0.4
a-As2S3 290 < 0.01 > 10
a-As2Se3 1200 1.0 2
Data quoted for l = 1550 nm: Opt. Express 15, 9205 (2007)
2-10 micron
supercontinuum
generation in ChG
waveguides
Opt. Lett. 41, 958
(2016)
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Phase change chalcogenide alloys
✓ Index change: Dn = 2.6
× Loss: k = 0.06 (22000 dB/cm)
Dn
k
The classical GST phase
change alloys are lossy
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Broadband low-loss phase change alloys
✓ Index change: Dn = 1.8
× Loss: k < 0.001
Dn
k
1 2FOM , FOMn k
k k
D D
FO
M2
/ 10
FO
M1
/ 10
GST GSS4T1
Data from V.
Liberman & J.
Chou @ LL
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Non-volatile switching by phase change alloys
Amorphous
Crystalline
Optical loss in GST limits
insertion loss and switching
contrast ratio
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Non-volatile switching by phase change alloys
Amorphous
Crystalline
Transparent phase change
material enables high-
contrast, low-loss switching
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
2-D materials
Monolithic photonic integration on 2-D materials
Flexible planar photonics
Integration with nanomembranes and elastomers
Glass photonic integration
ChGs are uniquely poised for multi-material integration
Introduction
Chalcogenides (ChGs): an emerging optical material
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Introduction
Chalcogenides (ChGs): an emerging optical material
2-D materials
Monolithic photonic integration on 2-D materials
Flexible planar photonics
Integration with nanomembranes and elastomers
Glass photonic integration
ChGs are uniquely poised for multi-material integration
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Photonic integration necessarily involve different
materials
Source Modulator DetectorWaveguide
Isolator
III-V
semiconductor
Electro-
optic crystal
Photonic
glass
SemiconductorMagneto-
optical
garnet
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
V
Glass
waveguide
Optical crystal
Polymer
2-D material
Semiconductor
Glass-based multi-material integration
Rubber
Ceramics & Metal
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
ChGs for multi-material photonic integration
Epitaxy-free deposition?
Low deposition temperature?
Cl
F
At
Br
I
P
N
Bi
As
Sb
S
O
Po
Se
Te
Al
B
Tl
Ga
In
Si
C
Pb
Ge
Sn
Chalcogenide
glass (ChG)
have weaker
interatomic
bonds than
those in oxides
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Epitaxy-free deposition
Low deposition temperature
Versatile microfabrication
?
?
?
ChGs for multi-material photonic integration
2 µm
Waveguide loss:
0.5 dB/cm
Cavity Q-factor:
1.2 × 106
Opt. Lett. 41, 3090-
3093 (2016).
Ge23Sb7S70
glass waveguide
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Epitaxy-free deposition
Low deposition temperature
Versatile microfabrication
?
?
?
Tailorable optical properties?
ChGs for multi-material photonic integration
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
2-D materials
Monolithic photonic integration on 2-D materials
Flexible planar photonics
Integration with nanomembranes and elastomers
Glass photonic integration
ChGs are uniquely poised for multi-material integration
Introduction
Chalcogenides (ChGs): an emerging optical material
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Introduction
Chalcogenides (ChGs): an emerging optical material
Flexible planar photonics
Integration with nanomembranes and elastomers
Glass photonic integration
ChGs are uniquely poised for multi-material integration
2-D materials
Monolithic photonic integration on 2-D materials
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
2-D materials in photonics
Nat. Photonics 8, 899-907 (2014)
✓ Light emission and detection
✓ Optical modulation
✓ Saturable absorption
✓ Optical nonlinearity
✓ Magneto-optical activity
✓ Tunable plasmonics
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Photonic integration of 2-D materials relies on
hybrid transferNature 474, 64-67 (2011)
Fabricated device 2-D layer transfer
Hybrid transfer:
× 2-D layer rupture at pattern
edges
× Weak evanescent interaction
× Limited throughput and
integration capacity
Monolithic integration:
✓ Improved yield and
throughput
✓ Flexible 2-D layer placement
✓ Superior alignment accuracy
× Material degradation
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Thick dielectric growth on graphene is difficult
due to its inert surface
Nano Lett. 10, 3572-3576 (2010)
Dielectric
deposition
× Mobility degradation
× ALD dielectrics: low
throughput for optical
devices
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Chalcogenide glass-on-2D-material photonics
ChG maintains the structural
and optoelectronic properties
of graphene
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Chalcogenide glass-on-2D-material photonics
MoS2
Black
phosphorus
InSeHexagonal
BN
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Chalcogenide glass-on-2D-material photonics
Black
phosphorus
30 nm
Ge23Sb7S70
glass film
The multifunctionalChG material
✓ Broadband light
guiding medium
✓ Passivation layer
for 2-D materials
✓ Gate dielectric
arXiv:1703.01666
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Broadband on-chip waveguide polarizer
Strong birefringence due to optical
anisotropy of graphene and
waveguide modal symmetry
arXiv:1703.01666
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Insertion loss Contrast ratio Length
Nat. Photonics 5, 411 (2011) 5 dB 23.6 dB 2100 mm
Our device 0.8 dB 23 dB 400 mm
Broadband on-chip waveguide polarizer
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Broadband on-chip waveguide polarizer
Octave-spanning broadband performance
Bandwidth with > 20 dB
contrast ratio:
❖ Experiment: 0.98 mm
& 1.55 mm
❖ Theory: 0.94 – 2.5 mm
arXiv:1703.01666
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Graphene as an energy-efficient transparent
heater
✓ Vanishing parasitic
optical loss
✓ Minimal thermal mass
✓ Large spatial overlap
between heating zone
and optical mode
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Graphene as an energy-efficient transparent
heater
Heating
efficiency:
10 nm/mW
t = 14 ms
Low-loss, broadband, energy-efficient transparent electrode
FOM 1.5 mW μsP t
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Waveguide-integrated mid-IR detector
Pauli blocking
Broadband mid-IR response with a peak responsivity of 250 mA/W
arXiv:1703.01666
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
The first graphene mid-IR waveguide modulator
ChG functions simultaneously as an infrared-transparent
gate dielectric and the light guiding medium
arXiv:1703.01666
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
The first graphene mid-IR waveguide modulator
arXiv:1703.01666
TheoryExperiment
8 dB/mm modulation depth at 2.05 mm wavelength
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Chalcogenide glass-on-2D-material photonics
&
The multifunctional ChG
✓ Direct deposition on 2-D
materials without surface
modification
✓ Broadband light guiding
medium
✓ 2-D material passivation
✓ Gate dielectric
2-D materials
✓ Large-area, catalyst-free
growth on semiconductor
substrates
✓ Broadband operation
✓ Unique optical functions
✓ Optoelectronic properties
readily tuned by gating
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
2-D materials
Monolithic photonic integration on 2-D materials
Flexible planar photonics
Integration with nanomembranes and elastomers
Glass photonic integration
ChGs are uniquely poised for multi-material integration
Introduction
Chalcogenides (ChGs): an emerging optical material
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Introduction
Chalcogenides (ChGs): an emerging optical material
Glass photonic integration
ChGs are uniquely poised for multi-material integration
Flexible planar photonics
Integration with nanomembranes and elastomers
2-D materials
Monolithic photonic integration on 2-D materials
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Flexible photonics: the next-generation photonic technology
Manufacturing
Integration & packaging
Applications
Roll-to-roll
manufacturing
Packaging in space-
constrained settings
Wearable devices
Bio-integration
Photonic tuning
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Transfer printing of flexible devices is limited in
yield and integration capabilities
SOI Handle wafer
PI precursor
Polymer
PDMS
device
Si nano-membrane
Handle wafer
PI
AuSiPI
Image courtesy of Dr. N. Lu @ UT Austin
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Elastomer/glass thermal expansion mismatch
Glass
PDMS
Material CTE (ppm/°C)
PDMS (elastomer) 310
Ge23Sb7S70 glass 21
Material CTE (ppm/°C)
PDMS (elastomer) 310
Ge23Sb7S70 glass 21
SU-8 epoxy 52
SU-8 epoxy effectively releases
thermal stress
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Making stretchable photonics out of rigid glass
Grating
coupler
Resonator
Devices on locally stiffened
islands interconnected by
serpentine waveguides
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Stretchable glass device fabrication
Non-
deformedStretched
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Stretchability of serpentine waveguides
Serpentine waveguides are robust against repeated stretching
0% elongation
36% elongation
▪ Before 3000 cycles @ 42%
▪ After 3000 cycles @ 42%
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Strain-optical coupling in waveguide devices
00
Leff
L
eff
it t g io i i
d dLL
n n
nn
ll
Light into waveguide
Optical resonator 0
eff
N L N Zn
l
Resonant condition:
Stress-induced resonance shift:
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Strain-optical coupling in waveguide devices
Can we correlate the resonant wavelength shift with local strain?
00
Leff
L
eff
it t g io i i
d dLL
n n
nn
ll
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Strain-optical coupling in waveguide devices
Length change X-section change Photoelasticity
Summing over all stress components
Can be derived from mechanical simulations
i
i
nn
D
i
A B B
B A B
B B An
C
C
C
where
Shear stress has no contribution
Two parameters!
00
Leff
L
eff
it t g io i i
d dLL
n n
nn
ll
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Predicting strain-optical coupling
Substrate stiffening
decreases local
strain by 25-fold
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Flexible waveguide integrated photodetectors
Metal-semiconductor-
metal (MSM) detector
InGaAs
Metal Metal
0+–
V
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Flexible waveguide integrated detector fabrication
❖ Fully leverages standard semiconductor fabrication processes
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Optical
input
Modeling of detector performance at 1550 nm
SU-8 top cladding
SU-8 bottom cladding
GeSbS
InGaAs
2 mm
❖ 80% quantum efficiency
❖ 10% reflection and scattering
❖ 10% transmitted (not absorbed)
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Nanopositioner
Polarization
controller
CCD & lamp
Microscope
Motion stages
Tunable laserOptical fiber
Computer
control
Power meter
Nanopositioner
Optical fiber
Device
Bright field
illumination
Semiconductor
parameter analyzer
Micro-probe
Electrical cable
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Detector response to waveguide input
Laser power
250 mW
Dark
At 5 V bias:
❖ Dark current ~ 1 nA
❖ Photo current 120 mA
Responsivity: 0.35 A/W
Quantum efficiency: 30%
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Mechanical testing
5 V bias
The device can withstand sub-millimeter bending without
performance degradation
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
2-D materials
Monolithic photonic integration on 2-D materials
Flexible planar photonics
Integration with nanomembranes and elastomers
Glass photonic integration
ChGs are uniquely poised for multi-material integration
Introduction
Chalcogenides (ChGs): an emerging optical material
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
V
Glass
waveguide
Optical crystal
Polymer
2-D material
Semiconductor
Glass-based multi-material integration
Rubber
Ceramics & Metal
Juejun (JJ) Hu
hujuejun@mit.eduPMAT
Si, LiNbO3, InP,
polymer…ChGs, 2-D crystals, &
other emerging optical
materials
Questions?
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