Abstract
We computationally study a subwavelength dielectric grating structure, show that slab waveguide modes can be used to obtain broadband high reflectivity, and analyze how slab waveguide modes influence reflection. A structure showing interference between Fabry-Perot modes, slab waveguide modes, and waveguide array modes is designed with ultra-broadband high reflectivity. Owing to the coupling of guided modes, the region with reflectivity R > 0.99 has an ultra-high bandwidth (Δf / ̅f > 30%). The incident-angle region with R > 0.99 extends over a range greater than 40°. Moreover, an asymmetric waveguide structure with a semiconductor substrate is studied.
Highlights
Subwavelength structures are of interest in a wide range of theoretical fields and applications, including cavity quantum electrodynamics, polariton lasers, filters, splitters, and couplers
We computationally study a subwavelength dielectric grating structure, show that slab waveguide modes can be used to obtain broadband high reflectivity, and analyze how slab waveguide modes influence reflection
A structure showing interference between Fabry-Perot modes, slab waveguide modes, and waveguide array modes is designed with ultrabroadband high reflectivity
Summary
Subwavelength structures are of interest in a wide range of theoretical fields and applications, including cavity quantum electrodynamics, polariton lasers, filters, splitters, and couplers. When these two curves show similar slopes, broadband high reflectivity occurs at the intersection; otherwise, high-Q resonances occur. On the other hand, when two types of modes have similar dispersion slopes, the reflected wave phases resulting from the two coupling modes interfere with each other, attenuating the transmission power in a large frequency range This phenomenon indicates that different dispersion relations can be engineered for various applications by modifying the parameters of the structure. 0.5 (red dashed line), and h2 0.45 and 0.55 (blue dash-dotted line)
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