A Field Guide to Azopolymeric Optical Fourier Surfaces and Augmented Reality

In optical devices like diffraction gratings and Fresnel lenses, light wavefront is engineered through the structuring of device surface morphology, within thicknesses comparable to the light wavelength. Fabrication of such diffractive optical elements involves highly accurate multistep lithographic processes that in fact set into stone both the surface morphology and optical functionality, resulting in intrinsically static devices. In this work, this fundamental limitation is overcome by introducing shapeshifting diffractive optical elements directly written on an erasable photoresponsive material, whose morphology can be changed in real time to provide different on-demand optical functionalities. First a lithographic configuration that allows writing/erasing cycles of aligned optical elements directly in the light path is developed. Then, the realization of complex diffractive gratings with arbitrary combinations of grating vectors is shown. Finally, a shapeshifting diffractive lens that is reconfigured in the light-path in order to change the imaging parameters of an optical system is demonstrated. The approach leapfrogs the state-of-the-art realization of optical Fourier surfaces by adding on-demand reconfiguration to the potential use in emerging areas in photonics, like transformation and planar optics.

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“…This results into a spiral quasicrystal DOE, whose fabrication would be very demanding in standard sequential interference lithography. [ 39,43 ]…”

Section: Resultsmentioning

confidence: 99%

Shapeshifting Diffractive Optical Devices

Oscurato

Reda

Salvatore

et al. 2022

Laser & Photonics Reviews

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“…[51][52][53] Moreover, the patterns developed in the current study can also be expected for applications in Fourieroptics-based devices for virtual reality and augmented reality. [71,72] When the illumination time further increases after the first stage, the spontaneous structure formation becomes obvious, which causes the appearance of more involved morphologies. The spontaneously formed structures tend to connect those already formed in the first stage, which causes the morphology evolution and topographical transition to exhibit different pathways.…”

Section: Discussionmentioning

confidence: 99%

Laser‐Induced Transitions of Azo Molecular Glass Pillar Arrays: A New Way to Fabricate Periodic Complex Surface Patterns upon Linearly Polarized Radiation

Wang

Huang

Hsu

et al. 2022

Advanced Optical Materials

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laser processing methods are laser direct writing (LDW) and interference lithography (IL). [7][8][9] LDW utilizes a focused laser spot to write designed patterns through effects such as laser heating, photochemical reactions, ablation, etching, and plasma formation. [6,7] On the other hand, IL is accomplished by recording the interference patterns in a photoresist, where the single or multiple optical exposures produce straight lines, curves, dots, hollows, and various other structures. [8,9] More specialized methods have also been developed to go beyond the optical diffraction limit for laser precision engineering, which include the laser-processing in near field, laser-particle lithography, plasmonic nanolithography, multiphoton lithography, block-copolymer lithography, and others. [7,10] An unexpected observation and discoveries of laser-induced periodic surface structures (LIPSS), often termed ripples, have led to another new approach with various applications. [11,12] LIPSS was originally observed as weird surfacerelief periodic lines on solids after laser radiation. [13,14] Later studies found that these structures can be generated on almost every type of material (metals, semiconductors, and dielectrics) upon irradiation of pulse lasers with durations down to a few femtoseconds, where the formed patterns show close correlation with the wavelength and polarization of the radiation. [11,[14][15][16][17] The universal and intriguing nature of LIPSS has triggered remarkable research enthusiasm to understand its mechanism. [11,[18][19][20] As the ripple sizes are much smaller than the spot area, LIPSS can be used for nanoscale surface patterning and other applications. [12] Although LIPSS as a unique surface pattering method is widely explored with many interesting developments, the patterns formed through this approach are more or less limited to ripples and most of them are produced by expensive ultrafast pulse lasers.Azo polymers and azo molecular glasses (polymers and molecular amorphous materials containing azo chromophores) represent a fascinating class of photoresponsive materials, which have been intensively investigated for the fabrication of various surface patterns. [21][22][23][24][25][26][27][28][29][30][31] Among the first cases of the developments, surface-relief-gratings (SRGs) were inscribed on azo polymer films by exposure to interfering patterns of laser beams. [32,33] In contrast to the irreversible patterns obtained by A new approach to fabricate ordered complex surface patterns is established upon linearly polarized light (LPL) irradiation with a continuous wave laser. Distinct from typical laser-induced periodic surface structures, the ordered patterns are formed through unique topographical transitions of submicrometer pillar arrays of an azo molecular glass, when irradiated with LPL at 532 nm. As revealed by microscopic investigation and optical simulation, the structure formation results from the deformation of the original pillars along the electric vibration direction of LPL and grow...

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“…However, the interest towards azobenzenes has not decreased, yet it has taken different, unprecedented directions, especially related to the integration of such photoswitches into materials for, e.g., dynamically controlling materials properties and biological phenomena [4,[6][7][8]. Especially the manifestations of "azobenzene photomechanics" [9] have been intensively studied, yielding photoactuable "life-like" motions [10] and soft robotic systems [11][12][13][14] and photopatternable surfaces for photonic applications [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

New tricks and emerging applications from contemporary azobenzene research

Fedele

Ruoko

Kuntze

et al. 2022

Photochem Photobiol Sci

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Azobenzenes have many faces. They are well-known as dyes, but most of all, azobenzenes are versatile photoswitchable molecules with powerful photochemical properties. Azobenzene photochemistry has been extensively studied for decades, but only relatively recently research has taken a steer towards applications, ranging from photonics and robotics to photobiology. In this perspective, after an overview of the recent trends in the molecular design of azobenzenes, we highlight three research areas where the azobenzene photoswitches may bring about promising technological innovations: chemical sensing, organic transistors, and cell signaling. Ingenious molecular designs have enabled versatile control of azobenzene photochemical properties, which has in turn facilitated the development of chemical sensors and photoswitchable organic transistors. Finally, the power of azobenzenes in biology is exemplified by vision restoration and photactivation of neural signaling. Although the selected examples reveal only some of the faces of azobenzenes, we expect the fields presented to develop rapidly in the near future, and that azobenzenes will play a central role in this development.

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A Field Guide to Azopolymeric Optical Fourier Surfaces and Augmented Reality

Cited by 29 publications

References 69 publications

Shapeshifting Diffractive Optical Devices

Shapeshifting Diffractive Optical Devices

Laser‐Induced Transitions of Azo Molecular Glass Pillar Arrays: A New Way to Fabricate Periodic Complex Surface Patterns upon Linearly Polarized Radiation

New tricks and emerging applications from contemporary azobenzene research

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