Systematic <i>λ</i>/21 resolution achieved in nanofabrication by two-photon-absorption induced polymerization

Bougdid, Yahya; Maouli, Imad; Rahmouni, Anouar; Mochizuki, Kimihiro; Bennani, I.; Halim, Mohammed; Sekkat, Zouheir

doi:10.1088/1361-6439/aafda0

Cited by 29 publications

(18 citation statements)

References 42 publications

(55 reference statements)

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“…Polymerization appears to depend on the local photochemical environment and the intensity distribution further away from the desired focal spots. Thus, reducing the distance between structures proves to be more challenging than reducing the feature sizes due to structure broadening [14][15][16] and sporadic connections [15,[17][18][19] that arise between them. When simultaneously exposing several spots, this effect is exacerbated and different local TPP thresholds are observed, for example, at the center and in the corner of a write spot array.…”

Section: Introductionmentioning

confidence: 99%

Understanding and overcoming proximity effects in multi-spot two-photon direct laser writing

Arnoux

Pérez-Covarrubias²,

Khaldi³

et al. 2022

Additive Manufacturing

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Although additive manufacturing using multi-photon direct laser writing is nowadays considered as a major tool in the fabrication of future nano/micro-objects and optical components, it is currently limited by the low throughput of the writing process. To circumvent this issue, massive parallelization of the write process is a very promising avenue. However, simultaneous writing of structures in close spatial proximity generates fabrication artefacts, collectively referred to as "proximity effects", which strongly limit the accessible structure resolution. In this work, we systematically investigate the experimental parameters that influence these effects using specifically designed N×N spot diffractive optical elements. Through computer simulations, we show that these effects can be modeled remarkably successfully simply by taking Point Spread Function overlap and diffusion processes into account. We illustrate the usefulness of the concept by designing a parallel write approach giving access to periodic structures with short inter-object distances while very largely overcoming proximity effects.

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Section: Introductionmentioning

confidence: 99%

Understanding and overcoming proximity effects in multi-spot two-photon direct laser writing

Arnoux

Pérez-Covarrubias²,

Khaldi³

et al. 2022

Additive Manufacturing

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“…More than two decades have passed since DLW was proposed and much progress has been made in terms of improving feature size and resolution, enlarging the library of materials that can be used, and the possible applications of these finely controlled structures . The research on functional materials—here intended as materials that can be employed in 2PP and show peculiar features that encourage their use in particular applications—has propelled the field of micro/nanostructuring forward by promoting the interdisciplinarity between chemistry, physics, biology, and material science .…”

Section: Introductionmentioning

confidence: 99%

Functional Materials for Two‐Photon Polymerization in Microfabrication

Carlotti

Mattoli

2019

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161

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The creation of 3D micro and nanostructures is of particular interest in the fields of photonics, [3] microelectromechanical systems (MEMS), [4] metamaterials, [5] micro/ nanofluidics, [6] cellular proliferation, and differentiation. [7] To create 3D objects of arbitrary shape, 3D printing techniques offer many versatile solutions. [8] Among these, direct laser writing (DLW) allows for the simple preparation of (sub)micrometric objects and patterns with a resolution that can go below 100 nm. [9][10][11] DLW is an additive manufacturing technique based on twophoton polymerization (2PP). To produce a structure, a fs-pulsed long-wavelength laser is focused, by means of optical elements, in a photosensitive resin which is able to crosslink (negative photoresist) or decompose (positive photoresist) under an energetic radiation but that is also transparent at the laser wavelength: if the intensity of the excitation radiation is high enough-as it is the case in the focus-the resin can undergo two (or more)-photon absorption and polymerize (or decompose). [12] Such multiphotons absorption phenomena are nonlinear and the cross-section of the different materials scales with the square (or higher) of the intensity of the radiation. For these reasons, the laser beam can enter the photoresist without being absorbed and trigger the photochemical process(es) only in a small volume around the focus. This volume is named "voxel" being the 3D analogue of a 2D pixel. [13] The absorption probability outside of the voxel is small, thus suppressing the propagation of the reaction and resulting in fine resolution. By moving around the voxel, one can obtain complex 3D structures that can be isolated after developing. [14,15] More than two decades have passed since DLW was proposed [16] and much progress has been made in terms of improving feature size and resolution, [9,[17][18][19][20][21] enlarging the library of materials that can be used, [22][23][24][25] and the possible applications of these finely controlled structures. [6,[25][26][27][28] The research on functional materials-here intended as materials that can be employed in 2PP and show peculiar features that encourage their use in particular applications-has propelled the field of micro/nanostructuring forward by promoting the interdisciplinarity between chemistry, physics, biology, and material science. [26] In this review, we will summarize and critically discuss the different functional materials proposed in the literature, dividing them and confronting them according to their preparation and their application (Figure 1; Table 1). We start the main body discussing the properties and applications of nanocomposite resists used in 2PP. In the second part, Direct laser writing methods based on two-photon polymerization (2PP) are powerful tools for the on-demand printing of precise and complex 3D architectures at the micro and nanometer scale. While much progress was made to increase the resolution and the feature size throughout the years, by carefully designing a material, one...

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“…In recent years, additive manufacturing or 3D printing techniques have gained significant interest, offering advantages over subtractive methods in terms of design freedom and mass customization, waste minimization, and rapid prototyping. − In particular, two-photon polymerization lithography (TPL) enables one to print structures at the hundred-nanometer length scale or even down to 10 nanometers under specific conditions. − Thus, this technology has been widely used for optical applications in the visible band, for instance, holograms without the zero-order spot for virtual reality, colorful 3D prints using photonic crystal structures, and holographic color prints for enhanced optical security in anticounterfeiting applications . However, due to the lack of a laser interferometric stage and precise height measurements in existing TPL systems, it is challenging to achieve high-quality DOEs with diffraction efficiencies close to the theoretical limit.…”

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confidence: 99%

Toward Near-Perfect Diffractive Optical Elements via Nanoscale 3D Printing

Wang

Zhang

et al. 2020

ACS Nano

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Diffractive optical elements (DOEs) are widely applied as compact solutions to generate desired optical patterns in the far field by wavefront shaping. They consist of microscopic structures of varying heights to control the phase of either reflected or transmitted light. However, traditional methods to achieve varying thicknesses of structures for DOEs are tedious, requiring multiple aligned lithographic steps each followed by an etching process. Additionally, the reliance on photomasks precludes rapid prototyping and customization in manufacturing complex and multifunctional surface profiles. To achieve this, we turn to nanoscale 3D printing based on two-photon polymerization lithography (TPL). However, TPL systems lack the precision to pattern diffractive components where subwavelength variations in height and position could lead to observable loss in diffraction efficiency. Here, we employed a lumped TPL parametric model and a workaround patterning strategy to achieve precise 3D printing of DOEs using optimized parameters for laser power, beam scan speed, hatching distance, and slicing distance. In our case study, millimeter scale near-perfect Dammann gratings were fabricated with measured diffraction efficiencies near theoretical limits, laser spot array nonuniformity as low as 1.4%, and power ratio of the zero-order spot as low as 0.4%. Leveraging on the advantages of additive manufacturing inherent to TPL, the 3D-printed optical devices can be applied for precise wavefront shaping, with great potential in all-optical machine learning, virtual reality, motion sensing, and medical imaging.

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Systematic λ/21 resolution achieved in nanofabrication by two-photon-absorption induced polymerization

Cited by 29 publications

References 42 publications

Understanding and overcoming proximity effects in multi-spot two-photon direct laser writing

Understanding and overcoming proximity effects in multi-spot two-photon direct laser writing

Functional Materials for Two‐Photon Polymerization in Microfabrication

Toward Near-Perfect Diffractive Optical Elements via Nanoscale 3D Printing

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