Design and Fabrication of Anti-Reflection Thin Films for Fiber Optic Communication Systems

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Design and Fabrication of Anti-Reflection Thin
Films for Fiber Optic Communication Systems
King Fahd University of Petroleum and Minerals
Electrical Engineering Department
Group E Mansour Al-Hagwi Ahmed Afif Amjad
Sindi Rayyan Al-Ghamdi
Advisors Dr. H. Masoudi Dr. E. Khawaja Dr. S. Ayub
19 May 2002
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In This Presentation

• Introduction
• Fabrication of Thin Films
• Physical Vapor Deposition
• Controlling the Thickness
• Measurements
• Spectrophotometer
• Single Layer Anti-Reflection Film (SLAR)
• Design and Fabrication
• Results
• Double Layer Anti-Reflection Film (DLAR)
• Design and Fabrication
• Results
• Inhomogeneous Films

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Introduction
Reflected Wave (4.3)
Transmitted Wave (95.7)
The aim of the project is to minimize the losses
due to reflection
Incident Wave
Glass
Air
Fiber Optic
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Introduction
No Reflection
Transmitted Wave (100)
Thin Film
Incident Wave
Glass
Air
Fiber Optic
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Introduction
Anti-Reflection Mechanism Multi-Reflection

• Important Parameters of Thin Films
• Refractive index (n)
• Thickness of the film (d)

Destructive Interference
Refractive index
n0
Air
n1
Film
n1
d
n2
Glass
Thickness
Constructive Interference
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Fabrication of Thin Films

• Physical Vapor Deposition
• Need of Vacuum
• Approaches
• Resistive Heating
• Electron Beam
• Controlling the Thickness
• Quartz Crystal Thickness Monitoring
• Optical Thickness Monitoring

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Fabrication of Thin Films

• Physical Vapor Deposition
• Resistive Heating
• Apply voltage to the terminals
• High current will pass
• Temperature increases
• Material evaporates in a shape
  of a cone

Coating Material
Small Boat
Terminals
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Fabrication of Thin Films

• Physical Vapor Deposition
• Electron Beam
• High power
• Concentration on a small
  surface

Electron Beam
e-
Pocket
Filament
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Fabrication of Thin Films

• Controlling the Thickness
• Quartz Crystal
• Quartz crystal is fixed
• Substrate is rotating
• gt Different positions
• gt Different amounts of evaporant
• gt Geometrical Factor (G)

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Fabrication of Thin Films

• Controlling the Thickness
• Optical Thickness Monitoring

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Measurements

• Dual Beam Spectrophotometer

Reflector
Detector 1
Reference Beam
Slit
Light Source
Sample Beam
Sample
Detector 2
Grating Monochromator
Splitter
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Single Layer Anti-Reflection Films

• Design of SLAR
• Fabrication of MgF2 Film
• Resistive Heating
• Quartz Crystal Thickness Monitor

Air (n01)
MgF2 (n11.38)
Film (n11.23)
Film (n1)
Glass (n21.52)
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Single Layer Anti-Reflection Films

• Results of MgF2 Film

RTheoretical 1.3
RExperimental 0.7
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Double Layer Anti-Reflection Films

• Design of Double Layer Film

(n0 1)
Air
NdF2 (n1 1.6)
Film 1 (n1)
Film 2 (n2)
WO3 (n2 2)
Glass (n3 1.52)

• Fabrication of Double Layer Film
• Resistive Heating
• Optical Thickness Monitor

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Double Layer Anti-Reflection Films

• Results of Double Layer Film

RExperimental 0.5
RTheoretical 0.02
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Inhomogeneous Films
Region 1
Region 2
gt
Microscopic view of inhomogeneous films (from
literature)
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Inhomogeneous Films

• Fabrication of CeO2 Film
• Electron Beam
• Quartz Crystal
• Experimental Results

RExperimental 0.1
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Conclusion
?
Uncoated Glass Single Layer Films Single Layer Films Double Layer Film
Material _____ MgF2 CeO2 NdF2 WO3
Theoretical Reflectance () 4.3
Experimental Reflectance () 4.2
Improvement in Reflectance () _____
_____
1.3
0.02
0.7
0.1
0.5
3.5
4.1
3.7
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Thank You