Inverse design of cavities for Bloch Surface Waves interfaced to integrated waveguides

Augenstein, Yannick; Roussey, Matthieu; Grosjean, Thierry; Descrovi, Emiliano; Rockstuhl, Carsten

doi:10.1016/j.photonics.2022.101079

Cited by 8 publications

(2 citation statements)

References 59 publications

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“…We use open-source finite-differential-time-domain (FDTD) solver MEEP [55] for the forward and backward simulations and MEEP's adjoint module [45] for updating the design parameters. The detailed flow chart of the adjoint optimization is described in the literature [56,57]. The total simulation space is 380 nm long along the x-and y-directions and 2250 nm high along the z-direction, where the simulation mesh size is 10 nm along the x-, y-, and z-directions.…”

Section: Resultsmentioning

confidence: 99%

Inverse designed WS₂ planar chiral metasurface with geometric phase

Jo,

Lee,

Bae

et al. 2024

J. Opt.

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Increasing attention is being paid to chiral metasurfaces due to their ability to selectively manipulate right-hand circularly polarized light or left-hand circularly polarized light. The thin nature of metasurfaces, however, poses a challenge in creating a device with effective phase modulation. Plasmonic chiral metasurfaces have attempted to address this issue by increasing light-matter interaction, but they suffer from metallic loss. Dielectric metasurfaces made from high index materials enable phase modulation while being thin. Very few materials, however, have high refractive index and low loss at visible wavelengths. Recently, some 2D materials have been shownto exhibit high refractive index and low loss in the visible wavelengths, positioning them as promising platform for meta-optics. This study introduces and details a planar chiral metasurface with geometric phase composed of WS2 meta-units. By employing adjointoptimization techniques, we achieved broadband circular dichroism (>0.5 in the wavelength range of 653–796 nm) and high extinction ratio (19.6dB at λ=675 nm).

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Section: Resultsmentioning

confidence: 99%

Inverse designed WS₂ planar chiral metasurface with geometric phase

Jo,

Lee,

Bae

et al. 2024

J. Opt.

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“…With the advent of the Plasmonics era, interest toward optical surface modes on planar dielectric stacks has seen a significant boost, mainly due to the possibility of overcoming some the inherent limitations of surface plasmons, especially in sensing applications [ 6 , 7 , 8 , 9 ]. In the last 20 years, optical surface modes (hereafter called Bloch Surface Waves, or BSW) on flat and patterned dielectric multilayers have been investigated in many frameworks, such as strong light–matter coupling [ 10 , 11 , 12 , 13 ], integrated [ 14 , 15 , 16 , 17 , 18 ], guided [ 19 , 20 , 21 , 22 ] and fiber [ 23 , 24 ] optics, label-free [ 25 , 26 , 27 , 28 ] and fluorescence-based [ 29 , 30 , 31 ] sensing, metrology, [ 32 ] photon management [ 33 , 34 , 35 , 36 ], light-driven particle manipulation, [ 37 , 38 ] emitting devices [ 39 , 40 ], microscopy imaging, and spectroscopy [ 41 , 42 , 43 ].…”

Section: Introductionmentioning

confidence: 99%

Bloch Surface Waves in Open Fabry–Perot Microcavities

et al. 2023

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Thanks to the increasing availability of technologies for thin film deposition, all-dielectric structures are becoming more and more attractive for integrated photonics. As light–matter interactions are involved, Bloch Surface Waves (BSWs) may represent a viable alternative to plasmonic platforms, allowing easy wavelength and polarization manipulation and reduced absorption losses. However, plasmon-based devices operating at an optical and near-infrared frequency have been demonstrated to reach extraordinary field confinement capabilities, with localized mode volumes of down to a few nanometers. Although such levels of energy localization are substantially unattainable with dielectrics, it is possible to operate subwavelength field confinement by employing high-refractive index materials with proper patterning such as, e.g., photonic crystals and metasurfaces. Here, we propose a computational study on the transverse localization of BSWs by means of quasi-flat Fabry–Perot microcavities, which have the advantage of being fully exposed toward the outer environment. These structures are constituted by defected periodic corrugations of a dielectric multilayer top surface. The dispersion and spatial distribution of BSWs’ cavity mode are presented. In addition, the hybridization of BSWs with an A exciton in a 2D flake of tungsten disulfide (WS2) is also addressed. We show evidence of strong coupling involving not only propagating BSWs but also localized BSWs, namely, band-edge and cavity modes.

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