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Integrated Photonic Devices
James Wilkinson
Optoelectronics Research Centre University of Southampton, UK
The Birth of Integrated Photonics
High-index “channel” on or in a flat substrate
Light guided by total internal reflection
Optical circuits may be made
“Evanescent” field results at waveguide surface
High-index
guiding channel Substrate
Electric field strength
EAJ Marcatili, Bell Labs
1978
“In 1969 my friend and boss,
S.E. Miller had the wonderful
idea of fabricating the many
components of optical
transmitters and receivers on a
single substrate using well-
known photolithographic
techniques. These devices were
very small (a few microns
across), precise, insensitive to
mechanical and thermal
transients and, if fabricated in
large numbers, economical.”
Advantages of the Planar Configuration
• Robustly interconnected multiple devices with economy of mass-production
• Localisation of gain and nonlinearity for example by dopant diffusion
• Simple variation of guide geometry by photolithography
• Access to evanescent fields
• Stable long lengths in small area
• Distributed functions such as pump-coupling and filtering
Fabrication Facility Layout
Fibre and Novel
Glass Integrated
Photonics
Southampton
Nanofabrication
Centre
Biophotonics
Thick Film
Bioelectronics
FIB
Integrated Photonics Cleanrooms
• Class 1000 cleanroom
• Photolithography
• Dip-pen nanolithography
• Sputtering, e-beam and thermal evaporation
• Ion-beam deposition
• Diffusion to 2300oC
• Reactive ion etching
• Chemically-assisted ion beam etching
• Microscopy, profilometry & SEM
Photolithography
Karl-Suss MA6 double-sided aligner
Define surface structures, electrodes,
optical circuits
Wide range of substrates
Resists – almost anything you can spin:
PMMA, SU-8, carbon
nanotubes in polymer
Max substrate size 4” diameter
Min feature size <1 micron
Dip-pen down to 10nm dots…
Sputtering, ion-beam, e-beam and thermal evaporation
Thin films of almost any material you want!
• Silica
• Germania-doped silica
• Erbium-doped tantala
• Indium tin oxide
• Pyrex
• Gallium lanthanum sulphide glass
• Bismuthate glass
• Gold, chromium, aluminium, silver, nichrome ..
• Neodymium, erbium, thulium, ytterbium …
• Lutetium biphthalocyanine
• Alumina
• Magnesium fluoride
• Teflon
• Germanium telluride glass
Etch almost any material you want!
Ar ion mill eg sapphire
150mm collimated
(+ FIB in separate facility)
Reactive ion etch eg SiO2
HF etch glass
Etching: Ion-Beam, Reactive and Wet
Diffusion and annealing
Diffuse almost anything into anything else!
• ≤ 600oC Salt-melt diffusion in glass (Ar, N2, O2)
• ≤ 1200oC Ti/Er diffusion into lithium niobate (Ar, N2, O2)
• ≤ 1700oC Glass softening and annealing (Ar, N2, O2)
• ≤ 2300oC Ga/Ti diffusion into sapphire (Vacuum, Ar, N2)
Depth (m)
012
Ga counts normalised0
1
Characterisation
2-D and 1-D stylus profilometry
~ 1nm step height resolution
~ 2μm lateral resolution
Microscopy
4-point probe for film sheet resistance
SEM AFM Optical
Waveguide lasers and amplifiers
● Er/Yb borosilicate glass waveguide laser & amplifier with 3dB/cm gain
● Nd-diffused LiNbO3 coupled-cavity tunable waveguide laser
● Ti-diffused sapphire waveguide laser for broad tunability
● Nd-doped Ta2O5 rib waveguide laser for photonic crystals
Er-doped Ta2O5 rib waveguide lasers and amplifiers for compact circuits
Channel Width of Mask / µm
4 6 8 10 12 14 16 18 20 22
Incid
en
t T
hre
sh
old
Pu
mp
Po
we
r /
mW
0
20
40
60
80
100
120
6µm wide 12.5µm wide 20µm wide
Integrated multisensor system “AWACSS”
32 analyte glass fluorescence sensor chip Instrument to handle fluids and analyse data
Fluorescent molecules within evanescent field are excited by light in waveguide
Light emitted from fluorescent molecules on 32 spots is detected in instrument
Trapping and manipulation at a surface
Light in
Downward force
Lateral forces Detection
“Radiation pressure”
forces
v1
v2
Optical Organisation of Gold Nanoparticles
What? • 125nm radius gold spheres in water
• Trapped and propelled on waveguide
• Speeds up to 0.7mm per second
Waveguide
Why? • Separation of gold-tagged biomolecules
• Organisation of regular arrays
• Surface-enhanced Raman spectroscopy
Laser light into
waveguide
Amplifiers & lasers: Er, Yb & Nd-doped glass and Ta2O5 on silicon
Filters, mirrors & resonators: with F.Diaz URV Tarragona and M.N. Zervas
Schematic of EDWA integration Gain spectra of Er:Ta2O5 guides Lasing spectra of Er:Ta2O5
Bottle-resonator add/drop mux Epitaxial KY1-x-yGdxLuy(WO4)2
ring resonators
Waveguide grating reflection spectra for
Er laser mirrors
Ta2O5 rib waveguide
photonic crystal filter
Integrated Photonic Devices
Excitation & manipulation of spheres & cells
Microsphere fabrication & resonator self-assembly
with D. Hewak, P.N. Bartlett, & M.N. Zervas
Integrated μsphere lasers:
Add lasing function to passive circuits
1055 1060 1065 1070
0
200
400
600
0
30
60
90
120
0
50
100
150
200
250
(c) Waveguide outputT
E(1
,23
5)
TE
(1,2
36
)
TE
(1,2
37
)
TE
(1,2
38
)
TM
(2,2
28
)T
M(3
,22
1)
TM
(1,2
36
)
TM
(1,2
37
)
TM
(1,2
38
)
(b)
Wavelength (nm)
Lasin
g p
ow
er
spectr
al density (
nW
/nm
)
Side
(a) Top
Waveguide optophoresis:
Microsphere and biological cell manipulation
with O.G.Hellesø, Uni. Tromsø, Norway
High-Q chalcogenide spheres
Chemical/physical assembly
Self-assembled waveguide grating
Surface microsphere sorting
Loop for standing-wave trapping Waveguide-coupled laser spectra
Nd-doped microsphere laser
Integrated Photonics for Bioanalysis
Wideband Integrated Photonics for Accessible Biomedical Diagnostics:
• Mid-IR materials
• On-chip spectroscopy and cytometry
• Nanostructured materials
• Point-of-care applications
32 analyte biosensor chip
Estrone, 2-4D, bisphenol A, simazine …
water pollution at LoD all below 20ng/L
Detector
Laser
Fibre
Microlens
Microchannel
Waveguide
Microchip
Optofluidic integration for microflow cytometers – planar kinoform lenses
Electrochemical plasmonics with Prof P.N. Bartlett, Chemistry
Come and join us!
