HARE Deposited Rib Waveguides

1
HARE Deposited Rib Waveguides

• V. Au
• D. A. P. Bulla ? C. Charles ? J. D. Love

Applied Photonics Group Space Plasma Plasma
Processing The Australian National University
Australian Photonics CRC
2
The HARE System
Si
Wafer
Process Chamber
Ge
Plasma Source
Crucibles
E-Gun
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The HARE Project

• Ultimately
• A low-loss waveguide for 1200nm lt l lt 1600nm
• Recent focus
• Optimizing the rib waveguide fabrication process
• Consider
• Modal properties
• Intrinsic thin film stress

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Modelling the HARE Rib Waveguide

• Input
• Geometry - dimensions of rib
• Properties - refractive index
• Propagating wavelength l

• Output
• Propagating modes - effective refractive
• index

• Cross-section of waveguide

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Modes of HARE Rib Waveguide
l 675nm Multi-moded

• 1310nm
• Single-moded

• The HARE rib waveguide Modelled modes vs
  experiment5mm ? 0.5mm rib

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The Multilayered Waveguide System

• Intrinsic stress in thin films
• type of substrate
• rate of deposition
• method of deposition

HARE Ge-doped SiO2

• Thin film stress
• thermal oxide-Si-thermal oxide (APOX)
• HARE deposited oxide on APOX1

APOX wafer

• For now
• stress in thermal oxide

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Adaption of Stoneys Equation
For a two layer system
Stoneys Equation
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Determining the Stress Relationships
Final
Initial
Bowing
? B(tA')

• Known
• 0.2 GPa lt s lt 0.4 GPa
• tensile

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Adaption of Stoneys Equation
For a two layer system
Stoneys Equation
Three layer system
?
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Curvature Experiment
tA
tS
tB
HF etch
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SiO2-Si-SiO2 Trilayer Determining B(tA')

• Model vs Experiment
• Experiment indicates B(tA') linear
• Equation of fit

• Stoney
• Nickel on steel

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Behaviour of Intrinsic Stress with Varied Film
Thickness

• Model vs Experiment
• Trilayer stress
• Substitute in
• Then
• ?
• ?

Constant
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Behaviour of Intrinsic Stress with Varied Film
Thickness

• Model vs Experiment
• SiO2-Si-SiO2 trilayer
• s 0.37 GPa
• tensile

• Stoney
• Nickel on steel

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Conclusions Future Directions

• Modelling of modes in HARE rib waveguide
• ? Model cladded HARE waveguide
• Developed the simplest trilayer model for thermal
  oxide
• ? Stress study in HARE deposited oxides

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Acknowledgements

• Directors Unit Ruth Jarvis
• EME Mladen Petravic
• Tom Halstead
• Workshop Tom McGuinness

Applied Photonics Group Space Plasma Plasma
Processing The Australian National University
Australian Photonics CRC