Modulation of Optical Properties in Liquid Crystalline Networks across Different Length Scales

Bellis, Isabella De; Martella, Daniele; Parmeggiani, Camilla; Pugliese, Eugenio; Locatelli, Massimiliano; Meucci, R.; Wiersma, Diederik S.; Nocentini, Sara

doi:10.1021/acs.jpcc.9b06973

Cited by 9 publications

(12 citation statements)

References 33 publications

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“…If Δ n o = 0.005, similar thickness variation as shown in lower panels of Figure 2a,b is obtained. The linear dependence of resonant peak shifts with temperature (Figure 2c) further suggests that the refractive index that varies non‐linearly with temperature in this temperature range [ 64 ] has a minor contribution to tuning. These findings indicate that the dominant tuning mechanism of the optical FP microcavities can be attributed to the thermomechanical response of the LCN, which is linear with temperature.…”

Section: Resultsmentioning

confidence: 99%

Dynamically Tunable Optical Cavities with Embedded Nematic Liquid Crystalline Networks

et al. 2023

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prompted a renewed interest in asymmetric Fabry-Pérot (FP) cavities, also termed Gires-Tournois resonators. They are comprised of one optically thick and one optically thin metallic mirror through which light can enter the structure. These optical elements are known for their ease of fabrication and effectiveness in resonating and enhancing light-matter interaction at selected wavelengths. [4,6,7] The general strategy to achieve dynamic tuning in FP resonators is to replace the passive insulator that commonly sits between the mirrors by dynamically tunable materials such as graphene, [11][12][13] phase-change magnesium, [14] electro-optical polymers, [15] liquid crystals (LCs) [16][17][18] and conducting oxides [19][20][21] via the field-effect. [22] Several works showed that electrical gating of indium-tin-oxide incorporated in the cavity facilitates control over light absorption [12,19] and its reflection phase in mid-infrared [20] and near-infrared. [21] Other research exploited electrochromic oxide [23] and polymers [24][25][26] with nanostructures to tune the resulting reflected color. Researchers showed that optical pumping of gallium-doped zinc oxide [27] and alumina [28] allows for ultrafast modulation of cavity resonances in a sub-picosecond regime. Tuning can also be achieved in non-conventional ways by light pressure, [29] directed self-assembly of nanoparticles in a liquid electrolyte [30] and by phase-tunable meta-mirrors. [31] To reduce fabrication complexity, a large variety of responsive materials Tunable metal-insulator-metal (MIM) Fabry-Pérot (FP) cavities that can dynamically control light enable novel sensing, imaging and display applications. However, the realization of dynamic cavities incorporating stimuliresponsive materials poses a significant engineering challenge. Current approaches rely on refractive index modulation and suffer from low dynamic tunability, high losses, and limited spectral ranges, and require liquid and hazardous materials for operation. To overcome these challenges, a new tuning mechanism employing reversible mechanical adaptations of a polymer network is proposed, and dynamic tuning of optical resonances is demonstrated. Solid-state temperature-responsive optical coatings are developed by preparing a monodomain nematic liquid crystalline network (LCN) and are incorporated between metallic mirrors to form active optical microcavities. LCN microcavities offer large, reversible and highly linear spectral tuning of FP resonances reaching wavelength-shifts up to 40 nm via thermomechanical actuation while featuring outstanding repeatability and precision over more than 100 heating-cooling cycles. This degree of tunability allows for reversible switching between the reflective and the absorbing states of the device over the entire visible and near-infrared spectral regions, reaching large changes in reflectance with modulation efficiency ΔR = 79%.

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Section: Resultsmentioning

confidence: 99%

Dynamically Tunable Optical Cavities with Embedded Nematic Liquid Crystalline Networks

et al. 2023

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“…can be rapidly and precisely adjusted to control the material response. Therefore, 4D printing of photoresponsive materials is promising for the fabrication of various optical structures [121][122][123][124]. Among the photoresponsive materials, azobenzene is the most widely studied.…”

Section: D Printing Of Photoresponsive Materials For Active Optical mentioning

confidence: 99%

3D and 4D printing for optics and metaphotonics

Jeong

Lee

et al. 2020

Nanophotonics

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AbstractThree-dimensional (3D) printing is a new paradigm in customized manufacturing and allows the fabrication of complex optical components and metaphotonic structures that are difficult to realize via traditional methods. Conventional lithography techniques are usually limited to planar patterning, but 3D printing can allow the fabrication and integration of complex shapes or multiple parts along the out-of-plane direction. Additionally, 3D printing can allow printing on curved surfaces. Four-dimensional (4D) printing adds active, responsive functions to 3D-printed structures and provides new avenues for active, reconfigurable optical and microwave structures. This review introduces recent developments in 3D and 4D printing, with emphasis on topics that are interesting for the nanophotonics and metaphotonics communities. In this article, we have first discussed functional materials for 3D and 4D printing. Then, we have presented the various designs and applications of 3D and 4D printing in the optical, terahertz, and microwave domains. 3D printing can be ideal for customized, nonconventional optical components and complex metaphotonic structures. Furthermore, with various printable smart materials, 4D printing might provide a unique platform for active and reconfigurable structures. Therefore, 3D and 4D printing can introduce unprecedented opportunities in optics and metaphotonics and may have applications in freeform optics, integrated optical and optoelectronic devices, displays, optical sensors, antennas, active and tunable photonic devices, and biomedicine. Abundant new opportunities exist for exploration.

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“…to steer a beam position (by modulating a mirror position with a rotating fibre), 36 or they can act themselves as photonic materials whose refractive indices and shape can be dynamically changed. 37 Light-tuneable photonic elements have been realized by DLW and integrated on existing photonic circuits to locally control the optical properties by a wireless optical stimulus. Some examples are reported in Figure 5: a 2D diffraction grating changing its pitch under light activation can steer the diffracted beam at different angles directing light in adjacent waveguides; 38 while a LCN cavity can be finely tuned by light to control the resonant frequency of a ring resonator.…”

Section: A Introductionmentioning

confidence: 99%