Ultrasensitive switching between resonant reflection and absorption in periodic gratings N. Komarevskiy, V. Shklover, L. Braginsky and Ch. Hafner Laboratory for Electromagnetic Fields (IFH), ETH Zurich, Switzerland
Guided-Mode Resonance (GMR) loss-free media 2
Guided-Mode Resonance (GMR) 100% reflection High Q-factor 3
4 Guided-Mode Resonance (GMR) Planar waveguide Corrugated waveguide Waveguide modes Modes folded into 1 st Brillouin zone (empty lattice) Resonance reflection
Guided-Mode Resonance (GMR) 5
Guided-Mode Resonance (GMR) k E normal incidence d 8; 2.13; sub d 800 nm 6
Guided-Mode Resonance (GMR) Silicon carbide N. Komarevskiy, V. Shklover, L. Braginsky, C. Hafner, and J. Lawson, Optics Express, 20, 14189-14200, 2012. 7
Guided-Mode Resonance (GMR) Silicon carbide N. Komarevskiy, V. Shklover, L. Braginsky, C. Hafner, and J. Lawson, Optics Express, 20, 14189-14200, 2012. 8
Guided-Mode Resonance (GMR) 9
High Sensitivity to Geometry & Permittivity Changes Sensor applications: biochemistry humidity pressure angle measurements 10
Example of Biosensor: Magnusson et al. 2011 Changes in real part of permittivity were considered! 11
Absorption Based Guided-Mode Resonance (AGMR) top interface is the perturbation strength 12
Solution in Terms of Plane Waves = 13
Effects of Small Losses: High-Q Absorption Resonances negligible spectral shift 14
High Angular Sensitivity of AGMR resonances split and may increase in strength 15
Linewidth of Reflection/Absorption Resonances exact linear three Fourier harmonics simplified 16
Linewidth of Reflection/Absorption Resonances ~ ~ ~ Absorption resonance is wider than reflection However, for small ε the difference is negligible 17
Numerical Examples: Hexagonal Lattice Normal incidence loss-free structure N. Komarevskiy, V. Shklover, L. Braginsky and Ch. Hafner, PIER, 139, 799-819, 2013. 18
Introduction of losses reflection drops to zero without spectral shift ' ' " negligible spectral shift 19
Hexagonal Lattice: Electric Energy Density N. Komarevskiy, V. Shklover, L. Braginsky and Ch. Hafner, PIER, 139, 799-819, 2013. 20
Linewidth of Reflection/Absorption Resonances strongly asymmetric symmetric Using FWHM definition, the absorption resonances can be narrower advantageous for sensor applications 21
Conversion of 100% Reflection to 100% Absorption 5 optimized parameters: 4 - geometrical 1- material ε N. Komarevskiy, V. Shklover, L. Braginsky and Ch. Hafner, PIER, 139, 799-819, 2013. 22
Conversion of 100% Reflection to 100% Absorption ε =0 Re{ E} ε =0.066 5 optimized parameters: 4 - geometrical 1- material ε 23
Thin Absorbing Film High Q-factor resonances, Q ~15 000 24
Graphene Monolayer Boundary conditions: Graphene absorption without corrugation is <2% (external fields can modify σ) 25
Angular Dependence resonances split and may increase in strength 26
Conclusions: Small ε cause absorption-based guided-mode (AGMR) resonances High Q-factor 100 % reflection to 100% absorption conversion Higher sensitivity with respect to ε than to ε High angular sensitivity (peaks split and increase in magnitude) Absorption causes structure heating; temperature detector scheme 27
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