Outlinedydaktyka2.wemif.pwr.wroc.pl/spatela/pdfy/0430.pdf · 2016-10-11 · (c) Sergiusz Patela...
Transcript of Outlinedydaktyka2.wemif.pwr.wroc.pl/spatela/pdfy/0430.pdf · 2016-10-11 · (c) Sergiusz Patela...
Principles of optoelectronic packaging
Dealing with the spaghetti of optical and electrical wires ...
Copying and processing permitted for non-commercial purposes, on condition that proper reference to the source is given.
© Sergiusz Patela, 2000-4
(c) Sergiusz Patela 2001 Photonic Devices. Optoelectronic Packaging 2
Outline
1. Introduction
2. Optics of optoelectronic packaging
3. Classifications and packaging systems
4. Optoelectronic package requirements
5. Assembly conditions
6. Generic optoelectronic package
7. Design solutions
8. Some notes about materials
(c) Sergiusz Patela 2001 Photonic Devices. Optoelectronic Packaging 3
Introduction
Packaging – a sequence of technologies that involve • connecting,• protecting,• and manufacturing of the devices
In optoelectronics the package accounts for 60 to 80 percent of current manufacturing expenses in component assembly (in microelectronic the proportion is reversed)
9010
Wafer processing Packaging
8020
O-e device Packaging
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Micro versus optoelectronic packaging - similarities, differences, challenges
Microelectronics devices
• high frequency design
• optimized automatic assembly
• planar design
• electrical connection
• components easily recognized (with metal lines as the references)
Optoelectronic devices
• high frequency design
• optimized for manual assembly
• 3D design, difficult visual inspection
• electrical and optical connections
• fiducial markings necessary to enable visualization and recognition of some elements
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Future – replacement of electrical interconnections with optical interconnections
• Limitations of classical electronic interconnections (speed, density).
• Compatibility of optical transmission systems and termination (switching, processing) modules
Sooner or later, the wire bonds will talk ...
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Optoelectronic device fabrication
• Wafer processing• Thin film processing• Device and subassembly packaging• Fiber handling and alignment• The finishing steps of tuning, adjusting and testing
Question - Why is it so challenging ?Answer - Multiple, proprietary fabrication techniques and processes involved, coupled with a lack of package and material handling standards.
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Optoelectronic devices assembly process
Chip fabrication
Cleave facets
Facet coatings
Package and wire bond
Burn-in test and bin
Mount and subassembl
y
Align and bond fiber
Test and labeling
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Technologies for optoelectronic device assembly
Process DescriptionEutectic component attach(for heat dissipation)
In-situ pulse heat, Au-Sn preform
Epoxy component attach Electrically conductive andnonconductive adhesives
Wire bond Au wire (25µm diameter), Au ribbon(75µm wide)
Fiber alignment Passive of activeActive component Laser, detector, lens, fiber
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Optics of optoelectronic packaging – light coupling
Optical loss factors:
1. Efficiency of power transfer (insertion loss)
2. Reflections reduction (back reflection)
Modeling issues: depending on device dimensions
• wave optics or
• ray optics approach has to be applied.
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Optoelectronic packaging, the history and the future
1. Early days - manual assembly
2. Contemporary - semiautomatic or automatic assembly; small or medium scale production
3. The future - fully automatic assembly; massive scale production; short time to market for new components
New diagnostic methods will be necessary optoelectronic devices/packages
Note - nowadays optoelectronic packages are complex devices themselves - composed of optical, microwave and thermal elements.
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Diagnostic methods for optoelectronic packaging
Testing
1. Operational propertiesoptical (power/sensitivity, coupling efficiencies, optical bandwidth)electrical DCelectrical RF
2. Structural properties (conformity with design detail, internal cracks and voids)
3. Thermal properties
Note: 3D visualization is required optical and optoelectrical elements of the package
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Mode Field Diameter
Power density profile of guided light beams can be approximated by Gaussian function:
( ) ( )
−=
2
0
2exp0wrprp
2wo is called the mode-field diameter (MFD). It is diameter at e-2 ~ 13.5% of Pmax
D
c
BACD
MFD
λλ+=
A, B, C, D = empirical parameters, λc – mode cutoff wavelength
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Optoelectronic packaging - classification according to the packaging system
Alignment type Notes 1 Passive Possible very high adjustment accuracy.
Inexpensive equipment. Different dies are needed for different application .
2 Active Universal equipment, can be expensive if high precision is required. Feedback during positioning guarantees device perfomance.
3 Mixed
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Example of mixed optoelectronic packaging
Schematic showing the construction of the package and the principle of the mixed packaging (note infrared die-bonding)
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Photonics devices to be packaged
Device types applications 1 Laser diodes FP, VCSEL, DFB,
DBR Telecommunications, datacom., sensors, aoutomotive industy.
6 Detectors Mainly semidonductor
All kinds of systems
2 DWDM multiplexers and switches
Grating, waveguide, FBG
High speed fiber optic transmission (SM)
3 Filters Intereference, FBG High speed fiber optic transmission (SM), sensors
4 Couplers Fused, integrated optics
Fiber optic systems of all kinds. SM, MM, POF fibers.
5 Isolators Magnetooptic rotators
High speed telecom. In connection with high quality lasers.
6 Optoelectronic integrated circuits
Advanced systems
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Design type and package requirements
Construction class Requirements 1 Free space Lenses, beam collimation,
(micro)optical beam-forming elements 2 Waveguides But-coupled waveguides, high
adjustment accuracies 3 Photonics devices arrays Thermal problems arise for emitting
devices. High packaging density (new connector styles may be required – e.g. SFF connectors).
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Application and package requirements
Application Packaging requirements 1 Telecommunications Mainly SM fibers, very high accuracy, 20+ years
working time 2 Datacom., networks High accuracy and reliability, SM and MM
fibers, in the future possibly POFs in massive market (FTTH)
3 Automotive industry Very high reliability, lower accuracy. 4 Medicine Special material requirements 5 Sensors Custom parameters, system dependent.
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Optoelectronic packaging - assembly conditions
“Optical-path” Assembly-Conditions
Requirements
1 Accuracy <1µm for SM systems, >1µm for MM systems. 10 up to 100µm for POFs and automotive applications.
2 Alignment (levels of freedom) X, Y, Z with different accuracies in different directions. Φ (angle).
3 Alignment method Visual (microscope, camera, image processing) or infrared (“see through the surface”, observation of “hot” active transmission devices (near infrared).
4 Other assembly issues Optical connection efficiency Electrical (electronic protection, ESD) Thermal Hermetization
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Communication system level packaging hierarchy
Level Contents general Contents optical Interconnection distance1. System level System service
functions Network interconnections ≥ 100 m
2. Cabinet level Functioning of the system on the rack
Cabinet level interconnection
~ 10 m
3. Unit level Interconnection between packages
Interconnection between modules
< 1 m
4. Board level Board functioning. Power supply
On-board device interconnections and signal transmission
~ 10 cm
5. Fiber level Placement Optical fiber placement ~ 1 cm 6. Beam level Stability, precision Beam focusing ~ 1 µm
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“Generic” optoelectronic package
electrical connections
support and temperature stabilization module
active element(s) with adjustment system
window, flat or lens
fiber
cover (hermetization)
fiber holder and adjustment segment
special optical elements (isolators, filters, …)
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Fiberoptic photonics systems
• Telecommunications systems. High performance, very high reliability and longevity (up to 30 years), very high unit price. Based on metal, glass, ceramic
• Access network systems. High performance and reliability, mediumlife times (10 years). Low unit price. Based on polymer materials
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Comparison of different LD – fiber coupling techniques
Butt coupling
Tapered waveguide coupling
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LD coupling with lenses possibilities
Single lens
double lens
cylindrical lens
GRIN lens
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singlemode waveguide
waveguide coreplanar waveguide
substrate
Butt - coupling of fiber and strip waveguides
additional block of substrate material
substrate with waveguide
polished surface
singlemode waveguide
Butt coupling of the waveguides with strengthening element
substrate
fiber waveguide
strenghtening element
UV-hardening glueblock of substrate material
epoxy gluestrip waveguide Waveguides connection with fiber
strengthening element (ruby bearing)
F-O to strip waveguide coupling
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singlemode waveguide
waveguide coreplanar waveguide
substrate
Butt - coupling of fiber and strip waveguides
Butt coupling vs.lensed fibers
singlemode waveguide
waveguide coreplanar waveguide
substrateLensed coupling of fiber and strip waveguides
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Angled waveguides coupling
Polymeric waveguide as short-distance optical interconnections. 45 mirrors applied for use as connects between MM fibers andVCSEL’s. Waveguide: d-PMME, UV-cured epoxy resin. Insertion coupling loss 1dB.
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Diluted waveguide (beam-shape engineering)
InP
InGaAsP
planarwaveguide
taperstrip
waveguide
towards fiberwaveguide
light towards optoelectronic element
Cylindrical field distribution, compatible with optical fiber
Elliptical field distribution, incompatible with optical fiber
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0
0,5
1
-1,E-05 -5,E-06 0,E+00 5,E-06 1,E-05
Fiberwaveguide
0
0,5
1
-1,E-05 -5,E-06 0,E+00 5,E-06 1,E-050
0,5
1
-1,E-05 -5,E-06 0,E+00 5,E-06 1,E-05
Optical field distribution of a planar and fiber waveguides. Misalignment results in large coupling losses.
Optical field distribution of fiber waveguide and thinned (tapered) planar waveguide.
Field widths are similar, but distributions still differ.
Optical field distribution shaped both by taper and diluted (multilayer) waveguide
Planarwaveguide
Fiberwaveguide
Planarwaveguide
FiberwaveguidePlanarwaveguide
Waveguide thickness [µm]
Waveguide thickness [µm]
Waveguide thickness [µm]
Diluted waveguide optical field distribution
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Simple standard package
Standard elements
Telecommunications PIN photodiode with fiber pigtail in standard TO5 package
Waveguide
PIN photodetector
TO5 package
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Design of the laser modulebaseplate
laser lens cap isolator holder
shuffle plate
fiber assemblylens isolator
sleve
laser lens isolator fiber
Fiber assembly
solderprimary coating
glue
H. van Tongeren, et al., IEEE Transactions on Components, Packaging and Manufacturing Technology - Part , vol. 18, (1995) 227.
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Optoelectronic packaging of advanced modules
Optoelectronic modulator in a microwave package. Package contains modulator chip, microwave preamplifier, impedance matching circuit.
Fiber waveguide microstrip line
Conducting glue
Alundum substrateMicrowave SMA connect.
Microwave package
U-grove
Laser diode package. Laser diode on submount, thermistorand photodiode
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Arrays packaging
Schematic structure of the 2-D VCSEL module
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Materials – selection criteria
1. Temperature properties (resistance, stability, resistance above 100C, 200C for short time, thermal coefficients of expansion)
2. Optical properties (attenuation, refractive index)
3. Mechanical properties
4. Manufacturability
5. Environmental resistance (weatherability)
6. Price, availability
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Package types utilized in optoelectronics
Component PackageDual-mode directfeedback laser
14-pin butterfly TO-56
Tunable laser High pin-count butterfly. Lowaspect ration custom package
Pump laser 14-pin butterfly TO-46External modulator High aspect ratio rectangular.
Custom packageVariable optical attenuator Coaxial cylindrical packageReceiver TO-3, TO-18, TO-46, Butterfly.
Low aspect ratio custom packageOptical switch Large square custom package.
Small cubic custom packageIsolator, coupler, splitter Differing length cylindrical
packages