Fundamentals of Thin Film Optics

Contents

Preface

Fundamentals of Thin Film Optics

1.1. INTRODUCTION

1.2. REVIEW OF THIN FILM OPTICS PRINCIPLES

1.3. REFLECTANCE DIAGRAMS AND DESIGN

1.3.1. Low Reflectors, Antireflection Coatings

1.3.2. Why Are Bubbles Colored?

1.3.3. Back Of The Envelope (BOTE) Calculations

1.3.4. Three-Layer AR Coating on Germanium, Example

1.3.5. Example Four-Layer Broad Band AR Coating in the Visible

1.3.6. Medium Reflectors and Beamsplitters

1.3.7. High Reflectors and Building Blocks

1.3.8. Crystal Coatings

1.3.9. Physical Thickness versus Optical Thickness

1.4. REFERENCES

Applications

2.1. INTRODUCTION

2.2. DESIGNING DIELECTRIC MIRRORS

2.3. ESTIMATING BANDPASS AND BLOCKER COATINGS

2.3.1. Estimating the Width of a Blocking Band

2.3.2. Estimating the Optical Density of a Blocking Band

2.3.3. Estimating the Number of Layers and Thickness Needed

2.4. DICHROIC REFLECTION COATINGS

2.5. NARROW BANDPASS FILTERS

2.5.1. Behavior of a High Index Slab

2.5.2. High Reflectors

2.5.3. NBP Wavelength Effects as Seen on Reflectance Diagrams

2.5.4. Dense Wavelength Division Multiplexing (DWDM) Filters

2.6. ESTIMATING DWDM FILTERS

2.6.1. Beamsplitters

2.7. ANGLES AND POLARIZATION

2.7.1. Wavelength Shift with Angle of Incidence

2.7.2. Polarization Effects of Angle of Incidence

2.7.3. Tilting for Tuning the Wavelength of a Filter

2.7.4. Polarization as Seen in Reflectance Amplitude Diagrams

2.7.5. Polarizing Beamsplitters

2.7.6. Non-Polarizing Beamsplitters

2.8. ADDITIONAL VIEWS VIA GRAPHICS AND PLOTS

2.8.1. Admittance Diagrams

2.8.2. Ellipsometry Plots

2.8.3. Additional Graphics for Visualization

2.9. APPROXIMATIONS OF INDICES AND DESIGNS

2.9.1. Herpin/Epstein Periods

2.9.2. More General Approximations

2.10. INHOMOGENEOUS INDEX FUNCTIONS

2.10.1. Step-Down Functions

2.10.2. Low Index Limitations

2.10.3. Lithographic “Moth-Eye” ARs

2.10.4. Overcoming Low Index Limitations With Thickness

2.10.5. Additional Thickness Functions

2.11. A FOURIER APPROACH

2.12. REFERENCES

Absorbing Materials

3.1. TRIANGLE DIAGRAMS AND DESIGN

3.2. DESIGNING COATINGS WITH ABSORBING MATERIALS

3.3. INDUCED TRANSMITTANCE FILTER

3.4. NBP REFLECTANCE FILTER EXAMPLE

3.5. NEUTRAL DENSITY FILTER EXAMPLE

3.6. CONCLUSIONS OF DESIGNING WITH METALS

3.7. REFERENCES

Advanced Design

4.1. HIGHER HARMONIC REFLECTION BANDS

4.2. MINUS FILTERS AND NARROW BLOCKING BANDS

4.3. FENCEPOST AND POSTHOLE DESIGN APPROACHES

4.3.1. Fencepost Design Examples

4.3.2. Edge Filters

4.3.3. Fencepost Narrow Bandpass Filters

4.3.4. Estimating OD and BW of Fenceposts

4.4. RUGATES AND EUV/SOFT X-RAY SPECTRAL REGION

4.5. QUANTIZATION EFFECTS IN EUV/X-RAY MIRRORS

4.6. FOURIER VIEWPOINT OF OPTICAL COATINGS

4.6.1. Fourier Concepts

4.6.2. Background

4.6.3. Some Limitations

4.6.4. A Method to Determine the Multiple Reflections

4.6.5. Fourier Summary

4.7. ESTIMATING EDGE FILTER PASSBAND REFLECTION

4.7.1. Procedure

4.7.2. Equations

4.7.3. Bandwidth Limitations on SWP Filters

4.7.4. Design Limitations of QWOT Stack SWP Filters

4.7.5. When Wider Passbands Are Needed for SWP Edge Filters

4.7.6. Optical Density and Band Edge Steepness

4.7.7. Squareness Between Edge and Passband

4.7.8. Wide Passband SWP Filters Conclusions

4.8. REFERENCES

Measurements

5.1. INTRODUCTION

5.2. SPECTROPHOTOMETERS

5.2.1 Dispersive Spectrometers and Spectrophotometers

5.2.2 Interferometric Spectrometers and Spectrophotometers

5.2.3 Fourier Transform Infrared versus Grating Instruments

5.2.4 Types of Reflecting Surfaces

5.2.5 The Original Recording Spectrophotometer

5.2.6 Measuring Absorption and Scattering

5.3. MEASURING %TRANSMITTANCE & %REFLECTANCE

5.3.1. Measuring Transmittance

5.3.2. Potential Measurement Problems

5.3.3. Measuring Reflectance

5.3.4. Checking Linearity of Reflectance Measurements

5.3.5. Other Reflectance Measurements

5.3.6. Photodiode Array Spectrometers

5.4. DENSITY or HUMIDITY SHIFT MEASUREMENT

5.5. CAVITY RING-DOWN MEASUREMENTS

5.6. COLOR MEASUREMENTS

5.6.1. Typical Color Filters

5.6.2. Plotting Colors on a C.I.E. 1931 and 1976 Diagrams

5.6.3. Comparing Gels and Optical Thin Film Coatings

5.6.4. Tolerancing the Production of Color Filters

5.6.5. Tolerancing and MacAdam Ellipses

5.6.6. Illuminants and Metameric Matches

5.6.7. Caution With Respect to Light Sources

5.7. REFERENCES

Finding Indices and Tooling Factors

6.1 INDEX & THICKNESS DETERMINATION

6.1.1. Index of Refraction Determination

6.1.2. Fitting Values for High Index Materials

6.1.3. Piecewise Fitting Using $NK in FilmStar

6.1.4. Fitting Values for Low Index Materials

6.1.5. Using the FilmStar Software Package for Index Fitting

6.2. ADVANCED USES OF SOFTWARE

6.2.1. Macro Commands and FilmStar Basic

6.2.2. Workbooks

6.2.3. “Manual” Fitting and Automation Assistance

6.2.4. Manually Tuning-In the Thickness of a Four-Layer AR

6.2.5. More Automated Tuning-In Via Macro and FilmStar Basic

6.2.6. More Automated Piecewise Fitting Via FilmStar Basic

6.3. REFERENCES

Designing Coatings

7.1. INTRODUCTION

7.2. ANTIREFLECTION COATINGS

7.2.1. Procedure

7.2.2. The Formula

7.2.3. Results

7.2.4. Berlin AR Design Contest

7.2.5. Results of Further Study

7.2.6. Estimating the Number of Layers

7.2.7. Looking Outside the Box

7.2.8. Reverse Engineering Using Number of Ripples in Band

7.2.9. Summary of Antireflection Coating Estimation

7.3. OPTIMIZATION

7.3.1. Performance Goals and Weightings

7.3.2. Global versus Local Minima

7.3.3. Some Optimizing Concepts

7.3.4. Constraints

7.4. DESIGNING A VERY BROAD BAND AR

7.4.1. Specific Example

7.4.2. Design Extension to Three Bands

7.5. OTHER EXAMPLES

7.6. DESIGNING A FILTER FOR 6P 3D COLOR

7.7. REFERENCES

Appendix Table of Conversion Factors

Index