Mid infrared polarization engineering via sub-wavelength biaxial hyperbolic van der Waals crystals

for electronic devices. Oxides constitute a broad family of materials with a wide range of potential applications, from catalysis to electronic, photonic, ferroelectric, magnetic and multiferroic functionalities. Understanding structure-property relations in free-standing, supported, and confined two-dimensional ceramics or "ceramic flatlands" has been identified as one of the challenges for future work in ceramics by a recent National Science Foundation workshop. [9] Nonetheless, over the last decade, there have been many reviews on 2D oxides either as the main focus or as a part of a more general nano-materials focused review papers or books. One of the earlier reviews of nanosheets of oxides and hydroxides focused on synthesis, properties -especially photon-induced behavior -and their assembly, was published in 2010 by Ma et al. [11], followed by a second review [12] as a part of a special issue on "2D Nanomaterials beyond Graphene" in 2015. Around the same time (2011) another review by Mas-Balleste et al.[13] also emphasized the importance and variety of 2D oxides. A more recent focused review on 2D oxides can be found in 2019 paper of Hinterding et al.

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“…They are therefore natural hyperbolic materials in this frequency range and this holds promise for interesting optical applications. [122,123]…”

Section: D Effects On Phonons: V2o5 and Moo3mentioning

confidence: 99%

Ultrathin 2D-oxides: A perspective on fabrication, structure, defect, transport, electron, and phonon properties

Radha

Crowley

Holler

et al. 2021

Journal of Applied Physics

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“…At higher α-MoO 3 thicknesses, Fabry-Pérot (FP) modes appear for p-polarized incident light within RB-1 spectral region. [29] Furthermore, the theoretical transmittance for s-polarized light in RB-1 spectral region is significantly small (0.001) obtaining which is practically difficult due to noise. Therefore, a reduction of experimental ER is expected in the RB-1 spectral region for transmission as well reflection mode.…”

Section: Resultsmentioning

confidence: 99%

High Temperature Mid‐IR Polarizer via Natural In‐Plane Hyperbolic Van der Waals Crystals

Sahoo

Dixit

Singh

et al. 2021

Advanced Optical Materials

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anisotropy is invoked by lithographic patterning, natural hyperbolicity of these vdW materials is attributed to structural anisotropy of crystal unit cell. In particular, hexagonal boron nitride (h-BN), [3] α-phase molybdenum trioxide (α-MoO 3 ) [1,6] and α-phase vanadium pentoxide (α-V 2 O 5 ) [2] are natural hyperbolic materials (NHMs) which exhibit Reststrahlen Bands (RBs)the spectral region between longitudinal optical (LO) and transverse optical (TO) phonons-in the mid-IR spectral region and show hyperbolicity due to interaction of optical phonons with photons (lightmatter interaction). Phonons have a relatively long lifetime compared to plasmons resulting in lower optical losses than their analogous plasmonic-based metamaterials [7][8][9] in which photons are coupled with plasmons. Many NHMs [1][2][3] exhibit hyperbolic anisotropy in mid-IR spectral region (3-30 µm) which has diverse applications like polarized IR imaging, [10] molecular sensing, [11,12] free space communication, [13] and quantum interference. [14] Unlike h-BN, which possesses uniaxial hyperbolic anisotropy (i.e., ε xx = ε yy ≠ ε zz ), α-MoO 3 exhibits in-plane hyperbolic anisotropy (i.e., ε xx ≠ ε yy ≠ ε zz ) which is particularly beneficial for planar mid-IR optical devices. [15,16] With this motivation, there has been recent interest in developing flat optics based on vdW layered materials which can be integrated with chip-scale platforms using vdW integration, operational at room temperature, and does not involve complex lithographic fabrication techniques. [17][18][19][20] We present an application of α-MoO 3 in the mid-IR spectral region, that is, from 545-1000 cm −1 (around 10-18 µm), as a thin film polarizer that reflects the light with one state of polarization while transmitting the light with its orthogonal state of polarization. Here, single-crystal α-MoO 3 thin films are synthesized using physical vapor deposition (schematically shown in Figure 1a) and are transferred on top of potassium bromide (KBr) window, purchased from Edmund Optics, using mechanical exfoliation technique. In-plane anisotropy of the synthesized α-MoO 3 thin film is confirmed using polarizationresolved Raman spectroscopy. We optimize the mid-IR optical responses of α-MoO 3 , mainly transmittance and reflectance, as a function of the thickness. Optimum thickness of α −MoO 3 based IR polarizer is found to lie in the range of 2.5-3.5 µm for which the extinction ratio (ER) is obtained more than 7.5Integration of conventional mid to long-wavelength infrared (IR) polarizers with chip-scale platforms is restricted by their bulky size and complex fabrication. Van der Waals materials based polarizer can address these challenges due to its nonlithographic fabrication, ease of integration with chip-scale platforms, and room temperature operation. In the present work, mid-IR optical response of the sub-wavelength thin films of α-phase molybdenum trioxide (α-MoO 3 ) is investigated for application toward high temperature mid-IR transmission and reflection type thin film...

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“…Dixit et al also proposed lithography-free and highly efficient MIR polarizers and rotators based on natural biaxial hyperbolic materials (e.g., α-MoO3 and α-normalV2normalO5 crystals), as shown in the left panel of Fig. 18(a) [285] . Incident light with frequency near the TO phonon is reflected along one state of polarization and transmitted along the other orthogonal state of polarization, which can be used to engineer the polarization of light in the MIR spectral range without using complex lithography.…”

Section: Polaritons Of Anisotropic 2d Materialsmentioning

confidence: 99%

Optical properties and polaritons of low symmetry 2D materials

et al. 2023

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Low symmetry 2D materials with intrinsic in-plane anisotropic optical properties and high tunability provide a promising platform to explore and manipulate light-matter interactions. To date, dozens of in-plane anisotropic 2D materials with diverse band structures have been discovered. They exhibit rich optical properties, indicating great potential for novel applications in optics, photonics, and optoelectronics. In this paper, we thoroughly review the anisotropic optical properties and polaritons in many kinds of low symmetry 2D materials, aiming to elicit more research interest in this field. First, the optical properties of anisotropic 2D semiconductors, including interband absorption, photoluminescence, excitons, and band structure engineering for tuning optical responses, are introduced. Then fundamentals and advances in experiments of hyperbolic polaritons in anisotropic 2D materials, including phonon, plasmon, and exciton polaritons, are discussed. Finally, a perspective on promising research directions is given.

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Mid infrared polarization engineering via sub-wavelength biaxial hyperbolic van der Waals crystals

Cited by 27 publications

References 55 publications

Ultrathin 2D-oxides: A perspective on fabrication, structure, defect, transport, electron, and phonon properties

Ultrathin 2D-oxides: A perspective on fabrication, structure, defect, transport, electron, and phonon properties

High Temperature Mid‐IR Polarizer via Natural In‐Plane Hyperbolic Van der Waals Crystals

Optical properties and polaritons of low symmetry 2D materials

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