A long-period grating formed in a single-mode optical fibre or waveguide may cause light coupling between your guided mode and the co-propagating cladding modes at specific resonance wavelengths and, therefore, create a transmission spectrum that includes a number of rejection-bands centered at those wavelengths. Just one long-period grating hence functions as a band-rejection filter. However, by placing several identical long-period gratings in parallel, light in the cladding modes dropped by the launching grating could be collected as outputs from another gratings(s). This type of long-period grating coupler functions being an add/drop multiplexer. Long-period gratings formed in optical fibers, referred to as long-period fibre gratings (LPFGs), have already been studied extensively and applied widely in optical communications and sensing. Couplers predicated on parallel LPFGs are also demonstrated recently….
Contents: Long-Period waveguide grating couplers
CHAPTER 1 Introduction
1.1 Long-period Fiber Gratings (LPFGs)
1.2 Long-Period Waveguide Gratings (LPWGs)
1.2.1 Fabrication of Long-Period Waveguide Gratings
1.2.2 Long-Period Waveguide Grating Filters
1.2.3 Long-Period Waveguide Grating Couplers
1.3 Objectives and Organization of the Thesis
References
CHAPTER 2 Coupled-Mode Analysis of a Single Long-Period Waveguide Grating
2.1 Introduction
2.2 Coupled-Mode Theory
2.3 Analysis of a Single LPWG
2.4 Design Example
2.5 Conclusion
References
CHAPTER 3 Analysis of Long-Period Waveguide Grating Couplers
3.1 Introduction
3.2 Coupled-Mode Equations
3.3 Transmission Characteristics
3.3.1 Offset z1 = 0
3.3.2 Offset 0 < z1 < L
3.3.3 Offset z1 ≥ L
3.4 Design Example
3.5 Conclusion
3.6 Appendix
3.6.1 Coupling of Three Modes
3.6.2 Coupling of Two Modes
References
CHAPTER 4 Analysis of Long-Period Waveguide Grating Array
4.1 Introduction
4.2 Coupled-Mode Analysis
4.3 Special Cases
4.3.1 N × N Power Distributor
4.3.2 2 × 2 Coupler
4.3.3 3 × 3 Coupler
4.3.4 4 × 4 Coupler
4.4 Design Example
4.5 Conclusion
4.6 Appendix
4.6.1 Solutions of the Coupled-Mode Equations
4.6.2 Conditions for an Arbitrary Distribution of Power Splitting Among the Waveguides
References
CHAPTER 5 Dissimilar and Non-Uniform Long-Period Waveguide Grating Array
5.1 Introduction
5.2 2 × 2 Non-Uniform Long-Period Waveguide Grating Couple
5.2.1 The Transfer Matrix Method
5.2.2 Results and Discussions
5.3 N × N Non-Uniform Long-Period Waveguide Grating Array
5.3.1 The Transfer Matrix Method
5.3.2 3 × 3 Non-Uniform 3-dB Power Splitter
5.4 Conclusion
References
CHAPTER 6 Cladding Mode Degeneracy in Long-Period Waveguide Gratings
6.1 Introduction
6.2 Cladding Mode Degeneracy in a Single Long-Period Waveguide Grating
6.3 Cladding Mode Degeneracy in a Long-Period Waveguide Grating Coupler
6.4 Design Example
6.5 Conclusion
References
CHAPTER 7 Experimental Demonstration of Long-Period Waveguide Grating Couplers…
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Source: City University of Hong Kong