Lithography-free IR polarization converters via orthogonal in-plane phonons in a-MoO3 flakes

Abstract

Exploiting polaritons in natural vdW materials has been successful in achieving extreme light confinement and low-loss optical devices and enabling simplified device integration. Recently, a-MoO3 has been reported as a semiconducting biaxial vdW material capable of sustaining naturally orthogonal in-plane phonon polariton modes in IR. In this study, we investigate the polarization-dependent optical characteristics of cavities formed using a-MoO3 to extend the degrees of freedom in the design of IR photonic components exploiting the in-plane anisotropy of this material. Polarization-dependent absorption over 80% in a multilayer Fabry-Perot structure with a-MoO3 is reported without the need for nanoscale fabrication on the a-MoO3. We observe coupling between the a-MoO3 optical phonons and the Fabry-Perot cavity resonances. Using cross-polarized reflectance spectroscopy we show that the strong birefringence results in 15% of the total power converted into the orthogonal polarization with respect to incident wave. These findings can open new avenues in the quest for polarization filters and low-loss, integrated planar IR photonics and in dictating polarization control.

References in corpus (12)

• Van der Waals heterostructures
• Graphene plasmonics
• Polaritons in layered 2D materials
• Graphene on hexagonal boron nitride as a tunable hyperbolic metamaterial
• Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging
• Infrared hyperbolic metasurface based on nanostructured van der Waals materials
• Subdiffractional focusing and guiding of polaritonic rays in a natural hyperbolic material
• All-angle negative refraction of highly squeezed plasmon and phonon polaritons in graphene-boron nitride heterostructures
• Infrared permittivity of the biaxial van der Waals semiconductor $\alpha$-MoO${}_3$ from near- and far-field correlative studies
• Active Tuning of Surface Phonon Polariton Resonances via Carrier Photoinjection
• Enhanced optical activity in hyperbolic metasurfaces
• Tunable plasmon-enhanced birefringence in ribbon array of anisotropic 2D materials

Cited by in corpus (9)

• Hybridized hyperbolic surface phonon polaritons at α-MoO3 and polar dielectric interfaces
• Microcavity phonon polaritons from weak to ultrastrong phonon-photon coupling
• A perspective of twisted photonic structures
• Two-dimensional natural hyperbolic materials: From polaritons modulation to applications
• Twist-angle and thickness-ratio tuning of plasmon polaritons in twisted bilayer van der Waals films
• Large-area polycrystalline $\alpha$-MoO3 thin films for IR photonics
• Optimization of highly circularly polarized thermal radiation in $\alpha$-MoO${}_3$/$\beta$-Ga${}_2$O${}_3$ twisted layers
• Spectrally Sharp Near-Field Thermal Emission: Revealing Some Disagreements between a Casimir-Polder Sensor and Predictions from Far-Field Emittance
• Unraveling phase transformation with phononic hyperbolicity using off-resonant terahertz light