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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, α-MoO3has 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 α-MoO3to 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 α-MoO3is reported without the need for nanoscale fabrication on the α-MoO3. We observe coupling between the α-MoO3optical 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.
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Design of near-perfect absorptance in few-layer WSe 2 via cooperative enhancement mechanisms
Two-dimensional transition metal dichalcogenides are of growing interest for flexible optoelectronics and power applications, due to their tunable optical properties, lightweight nature, and mechanical pliability. However, their thin nature inherently limits their optical absorption and, therefore, efficiency. Here, we propose a few-layer WSe2optoelectronic device that achieves near perfect absorption through a combination of optical effects. The WSe2can be scalably grown below an Al2O3superstrate. Our device includes a corrugated back reflector, modeled as a plasmonic nanowire array. We investigate the entire range of widths of the corrugations in the back reflector, including the edge cases of a simple back mirror (width equal to period) and a Fabry-Perot cavity (zero width). We demonstrate the zero-mode enhancement arising from the back reflector, the weakly coupled enhancement arising from the Fabry-Perot cavity, and the strongly coupled enhancement arising from the localized surface plasmon resonance of the nanowires, explain the physical nature of the spectral peaks, and theoretically model the hybridization of these phenomena using a coupled oscillator model. Our champion device exhibits 82% peak absorptance in the WSe2alone, 92% in the WSe2plus nanowires, and 98% total absorptance. Thus, we achieve a near-perfect absorber in which most of the absorption is in the few-layer WSe2, with a desirable device framework for integration with scalable growth of the WSe2, thereby making our designs applicable to a range of practical optoelectronic devices.
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- Award ID(s):
- 1846239
- PAR ID:
- 10524298
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optical Materials Express
- Volume:
- 14
- Issue:
- 8
- ISSN:
- 2159-3930
- Format(s):
- Medium: X Size: Article No. 1972
- Size(s):
- Article No. 1972
- Sponsoring Org:
- National Science Foundation
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