7 research outputs found
Twist-tunable moir\'e optical resonances
Multilayer stacks of twisted optical metasurfaces are considered as a
prospective platform for chiral nanophotonic devices. Such structures are
primarily used for the realization of circularly polarized light sources,
artificial optical rotation, and circular dichroism. At the same time, the
behavior of their hybrid photonic modes is strongly affected by the
moir\'e-pattern of superimposed periodic constituents. In this work, we show
that moir\'e-periodicity in bilayer dielectric photonic crystal slabs leads to
an arise of unlimitedly narrow optical resonances, which are very sensitive to
the relative twist and gap width between the sublayers. We demonstrate the
structure providing twist-tuning of the hybrid mode wavelength in the range of
300--600~nm with quality factor varying from~~up~to~
correspondingly. The obtained results pave the wave for the utilization of
moir\'e-assisted effects in multilayer photonic crystal slabs
Chiral light in twisted Fabry-P\'erot cavities
Fundamental studies of the interaction of chiral light with chiral matter are
important for the development of techniques that allow handedness-selective
optical detection of chiral organic molecules. One approach to achieve this
goal is the creation of a Fabry-P\'erot cavity that supports eigenmodes with a
desired electromagnetic handedness, which interacts differently with left and
right molecular enantiomers. In this paper, we theoretically study chiral
Fabry-P\'erot cavities with mirrors comprising one-dimensional photonic crystal
slabs made of van der Waals AsS, a material with one of the highest
known in-plane anisotropy. By utilizing the anisotropy degree of freedom
provided by AsS, we design Fabry-P\'erot cavities with constitutional
and configurational geometrical chiralities. We demonstrate that in cavities
with constitutional chirality, electromagnetic modes of left or right
handedness exist due to the chirality of both mirrors, often referred to as
handedness preserving mirrors in the literature. At the same time, cavities
with configurational chirality support modes of both handednesses due to chiral
morphology of the entire structure, set by the twist angle between the optical
axes of the upper and lower non-chiral anisotropic mirrors. The developed
chiral Fabry-P\'erot cavities can be tuned to the technologically available
distance between the mirrors by properly twisting them, making such systems a
prospective platform for the coupling of chiral light with chiral matter.Comment: 33 pages, 9 figure
Chiral light in twisted Fabry-P\'erot cavities
Fundamental studies of the interaction of chiral light with chiral matter are important for the development of techniques that allow handedness-selective optical detection of chiral organic molecules. One approach to achieve this goal is the creation of a Fabry-P\'erot cavity that supports eigenmodes with a desired electromagnetic handedness, which interacts differently with left and right molecular enantiomers. In this paper, we theoretically study chiral Fabry-P\'erot cavities with mirrors comprising one-dimensional photonic crystal slabs made of van der Waals AsS, a material with one of the highest known in-plane anisotropy. By utilizing the anisotropy degree of freedom provided by AsS, we design Fabry-P\'erot cavities with constitutional and configurational geometrical chiralities. We demonstrate that in cavities with constitutional chirality, electromagnetic modes of left or right handedness exist due to the chirality of both mirrors, often referred to as handedness preserving mirrors in the literature. At the same time, cavities with configurational chirality support modes of both handednesses due to chiral morphology of the entire structure, set by the twist angle between the optical axes of the upper and lower non-chiral anisotropic mirrors. The developed chiral Fabry-P\'erot cavities can be tuned to the technologically available distance between the mirrors by properly twisting them, making such systems a prospective platform for the coupling of chiral light with chiral matter
Nearly perfect routing of chiral light by plasmonic grating on slab waveguide
Grating couplers are widely used to couple waveguide modes with the far field. Their usefulness is determined not only by energy efficiency but also by additional supported functionality. In this paper, we demonstrate a plasmonic grating on a silicon nitride slab waveguide that couples both TE and TM waveguide modes with circularly polarized light in the far field. Specifically, we experimentally confirmed that circularly polarized light excites TE and TM modes propagating in opposite directions, and the direction is controlled by the handedness. The routing efficiency for normally incident light reaches up to 95%. The same structure operates in the outcoupling regime as well, demonstrating up to 97% degree of circular polarization, where the handedness is determined by the polarization and propagation direction of outcoupled modes. Our results pave the way for the realization of polarization-division multiplexers and demultiplexers, integrated circular polarization emitters, as well as detectors of the polarization state of the incident optical field
Wandering principal optical axes in van der Waals triclinic materials
Abstract Nature is abundant in material platforms with anisotropic permittivities arising from symmetry reduction that feature a variety of extraordinary optical effects. Principal optical axes are essential characteristics for these effects that define light-matter interaction. Their orientation – an orthogonal Cartesian basis that diagonalizes the permittivity tensor, is often assumed stationary. Here, we show that the low-symmetry triclinic crystalline structure of van der Waals rhenium disulfide and rhenium diselenide is characterized by wandering principal optical axes in the space-wavelength domain with above π/2 degree of rotation for in-plane components. In turn, this leads to wavelength-switchable propagation directions of their waveguide modes. The physical origin of wandering principal optical axes is explained using a multi-exciton phenomenological model and ab initio calculations. We envision that the wandering principal optical axes of the investigated low-symmetry triclinic van der Waals crystals offer a platform for unexplored anisotropic phenomena and nanophotonic applications
Data for manuscript "Wandering principal optical axes in van der Waals triclinic materials"
Data for manuscript "Wandering principal optical axes in van der Waals triclinic materials"</p