Liquid Crystal Pancharatnam–Berry Micro‐Optical Elements for Laser Beam Shaping

Jiang, M.; Yu, Hao; Feng, Xiayu; Guo, Yubing; Chaganava, Irakli; Turiv, Taras; Lavrentovich, Oleg D.; Wei, Qi‐Huo

doi:10.1002/adom.201800961

Cited by 41 publications

(29 citation statements)

References 57 publications

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“…[44,48] This PB phase can be readily seen using the Jones calculus. [44,48] This PB phase can be readily seen using the Jones calculus.…”

Section: Microlensesmentioning

confidence: 99%

“…It can be shown that when the thickness of the liquid crystal film is smaller than the characteristic length scale over which the PB phase varies by π, the incident (θ i ) and transmitted (θ t ) angle can be related to the PB phase Φ by the so-called generalized Snell's law [44] sin sin 2 The gradients of the PB phase cause the transmitted light to change its propagation direction.…”

Section: Microlensesmentioning

confidence: 99%

“…[13,14,21,[29][30][31][32][33][34] The PB microlenses made of liquid crystals are particularly attractive because of their close to 100% efficiency and switchable focal lengths. [30,33,37,38,[43][44][45][46][47] Here, we show that high-quality microlenses based on PB phases can be designed and made with liquid crystal polymers by using a plasmonic photopatterning technique. [42] These techniques have enabled various applications and research ranging from optical devices to programmable origami.…”

mentioning

confidence: 99%

“…[42] These techniques have enabled various applications and research ranging from optical devices to programmable origami. [30,33,37,38,[43][44][45][46][47] Here, we show that high-quality microlenses based on PB phases can be designed and made with liquid crystal polymers by using a plasmonic photopatterning technique. The plasmonic photopatterning technique allows for arbitrary molecular orientations encoded in designs of so-called plasmonic metamasks.…”

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confidence: 99%

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Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Jiang

Guo

et al. 2019

Advanced Materials

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For example, phase profiles required for lensing can be realized by sculpturing dielectric substrates with discretized steps or sloped ridges through photo lithography and reactive ion etching. [18][19][20] These lithography processes make diffractive microlenses more tailorable than refractive microlenses in terms of filling factor and low f-number. However, to achieve high performances, very complex fabrication processes are needed. For example, up to 8 lithography steps and sometimes electron-beam lithography are needed to achieve low f-numbers, [21][22][23] diffraction-limited performance, and over 90% efficiency. [19,[24][25][26] The phase profiles desired for lensing can also be realized with the Pancharatnam-Berry (PB) phases [27,28] by using birefringent materials or metasurfaces with spatially variant optical axes. [13,14,21,[29][30][31][32][33][34] The PB microlenses made of liquid crystals are particularly attractive because of their close to 100% efficiency and switchable focal lengths. [31,33,35,36] Large-sized PB lenses with low f-numbers can be made by holography photopatterning with a refractive master lens, [31] while liquid crystal PB microlenses are still limited to large f-number (>10) [32,33] and no work has been able to show diffraction-limited quality.A range of techniques have been developed in recent years to align liquid crystal molecules into arbitrary designer orientation patterns, which are either based on photoalignments using digital micromirror device (DMD), [37,38] pixel-to-pixel direct laser writing, [30] holography interference [31] and plasmonic photo patterning, [39][40][41] or based on nanostructured surfaces by using nanoimprinting [33] or atomic force microscopy scribing. [42] These techniques have enabled various applications and research ranging from optical devices to programmable origami. [30,33,37,38,[43][44][45][46][47] Here, we show that high-quality microlenses based on PB phases can be designed and made with liquid crystal polymers by using a plasmonic photopatterning technique. The plasmonic photopatterning technique allows for arbitrary molecular orientations encoded in designs of so-called plasmonic metamasks. We designed and fabricated microlenses with a set of focal lengths and f-numbers to test the quality and resolution limit of the plasmonic photopatterning technique. As discussed later, the microlenses with f-number down to 2 requires 1.5 µm of smallest molecular pitches.Microlenses are desired by a wide range of industrial applications while it is always challenging to make them with diffraction-limited quality. Here, it is shown that high-quality microlenses based on Pancharatnam-Berry (PB) phases can be made with liquid crystal polymers by using a plasmonic photopatterning technique. Based on the generalized Snell's law for the PB phases, PB microlenses with a range of focal lengths and f-numbers are designed and fabricated and their point-spread functions and ability to image micrometer-sized particles are carefully characterized. The results show that...

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“…[44,48] This PB phase can be readily seen using the Jones calculus. [44,48] This PB phase can be readily seen using the Jones calculus.…”

Section: Microlensesmentioning

confidence: 99%

Section: Microlensesmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Jiang

Guo

et al. 2019

Advanced Materials

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“…A variety of emerging applications become possible when spatially variant molecular orientation (also called molecular director) can be controlled at will. For example, liquid crystal Pancharatnam–Berry phase optical elements such as Q‐plates, lenses, and beam shapers can be made to modify the orbital angular momentum, propagation direction, and intensity profiles of light beams . The stimulus‐responsive deformations of liquid crystal elastomers can be preprogrammed in molecular director patterns, promising various applications in actuators and origami‐inspired surfaces .…”

mentioning

confidence: 99%

Plasmonic Metasurfaces with High UV–Vis Transmittance for Photopatterning of Designer Molecular Orientations

Guo

Turiv

et al. 2019

Advanced Optical Materials

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gation direction, and intensity profiles of light beams. [3][4][5][6][7][8] The stimulus-responsive deformations of liquid crystal elastomers can be preprogrammed in molecular director patterns, promising various applications in actuators and origami-inspired surfaces. [9][10][11][12][13][14] Liquid crystals with predesigned molecular director fields can enable controlling colloidal placements and assembly, [15] nonlinear electrokinetic flows, [16] and commanding active matter like swimming bacteria. [17] As the molecular director in bulk liquid crystals is set primarily by its condition at the bounding surfaces, [1] proper molecular alignment at surfaces is an essential step in liquid crystal device manufacturing. [18] Early applications and efforts were focused on uniform alignment, [18][19][20] while the emerging applications described above have driven rapid developments of techniques for aligning liquid crystal molecules into spatially variant directors. These techniques are based either on maskless approaches such as interference photo alignment [21] and pixel-to-pixel direct writing, [12,22,23] or on mask-based approaches such as using digital micromirror devices as a dynamic mask. [24,25] More recently, Guo et al. developed a technique for photopatterning molecular orientations by using engineered plasmonic metamasks (PMMs), in a fashion similar to projection photolithography. [26] In contrast to traditional photomasks in photolithography which generate only light intensity patterns, the PMMs generate spatially variant patterns of polarization directions. [26] Projecting such polarization patterns onto thin films of photoalignment materials leads to reorientation of the rod-shaped molecules according to the molecular director patterns encoded in the polarization patterns of the PMMs, which can then be imposed onto liquid crystals confined by these substrates. [26] This PMM-based photopatterning significantly increases the spatial resolution and throughput in controlling molecular orientations and has facilitated various exciting new applications. [8,13,[15][16][17]27,28] However, the existing design of the PMMs suffers from low optical efficiency in the near UV wavelengths, and PMMs with high optical transmittance are still needed to match the absorption bands of various photoalignment materials.Metasurfaces based on plasmonic and dielectric materials exhibit extraordinary capabilities in controlling the amplitude and phase profiles with subwavelength spatial resolutions. [29][30][31][32][33][34][35][36][37][38] However, efficient and robust metasurfaces working in the UV Recent developments of utilizing plasmonic metasurfaces in photopatterning of designer molecular orientations have facilitated numerous new applications of liquid crystals; while the optical efficiency of the metamasks remains a critical issue, especially in the UV region. Here a new design of plasmonic metasurfaces made of parallelepiped arrays is presented which yield very high and broadband transmission in the UV-vis wavelength range....

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Liquid‐Crystal‐Mediated Geometric Phase: From Transmissive to Broadband Reflective Planar Optics

et al. 2019

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Planar optical elements that can manipulate the multidimensional physical parameters of light efficiently and compactly are highly sought after in modern optics and nanophotonics. In recent years, the geometric phase, induced by the photonic spin–orbit interaction, has attracted extensive attention for planar optics due to its powerful beam shaping capability. The geometric phase can usually be generated via inhomogeneous anisotropic materials, among which liquid crystals (LCs) have been a focus. Their pronounced optical properties and controllable and stimuli‐responsive self‐assembly behavior introduce new possibilities for LCs beyond traditional panel displays. Recent advances in LC‐mediated geometric phase planar optics are briefly reviewed. First, several recently developed photopatterning techniques are presented, enabling the accurate fabrication of complicated LC microstructures. Subsequently, nematic LC‐based transmissive planar optical elements and chiral LC‐based broadband reflective elements are reviewed systematically. Versatile functionalities are revealed, from conventional beam steering and focusing, to advanced structuring. Combining the geometric phase with structured LC materials offers a satisfactory platform for planar optics with desired functionalities and drastically extends exceptional applications of ordered soft matter. Some prospects on this rapidly advancing field are also provided.

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Liquid Crystal Pancharatnam–Berry Micro‐Optical Elements for Laser Beam Shaping

Cited by 41 publications

References 57 publications

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Plasmonic Metasurfaces with High UV–Vis Transmittance for Photopatterning of Designer Molecular Orientations

Liquid‐Crystal‐Mediated Geometric Phase: From Transmissive to Broadband Reflective Planar Optics

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