Micro‐Optics 3D Printed via Multi‐Photon Laser Lithography

Abstract

3D printed objects was first presented by Maruo in a technology-opening article in 1997, [2] where the use of this technology to fabricate micro-optics was also envisaged. The serial writing method of this technique offered flexibility for freeform fabrication, but was limited by its throughput. [3] It took some years for the technology to mature from proof-of-principle level to additive manufacturing as a tool for efficient and reliable fabrication in the modern lab. [4][5][6] Though the first micro-optical elements were demonstrated as early as 2006, [7] the major efforts and results only started to emerge in 2010, [8,9] together with the development of hybrid organic-inorganic materials, [10,11] and rapidly accelerated with the implementation of commercial 3D lithography systems. [12][13][14] By 2020, ultrafast laser 3D printing, also known as two-photon polymerization (TPP or 2PP), multiphoton lithography (MPL), [15][16][17] or simply laser direct writing (LDW), also in literature referenced as direct laser writing (DLW), [18] ) was already an established technique for routine fabrication of diverse micro-optical single elements, stacked components, and integrated devices. [19][20][21] The latest advances in the 3D printing of free-form micro-optics are enhanced by optical grade materials of high refractive index (n) polymers, [22] high-performance hybrids, [23] and optically active [24] or pure inorganic glasses. [25] Figure 1 shows the development of the technique in terms of published papers and citations, defining an "innovator stage" of the technology followed from 2015 by the "early adopters stage." Examples of micro-optical elements fabricated using MPL and the growth in the complexity of the structures that can be achieved by this technique are also shown in Figure 1.The advances in this scientific field attracted the attention of the related laser-assisted precision additive manufacturing industry. First, in 2007 Nanoscribe GmbH and in 2008 Workshop of Photonics established companies oriented toward commercialization of this technology aimed at general wide angle application fields. While in 2013, Multiphoton Optics GmbH and Femtika UAB were established and made micro-optics a significant part of their targeted applications. Finally, in 2017, Vanguard Photonics GmbH manufactured dedicated MPL equipment for micro-lenses and wire bond production. Other companies targeting more diverse applications have continued to emerge, such as UpNano established in 2018, and focusing mostly on biomedical applications yet also offering solutionsThe field of 3D micro-optics is rapidly expanding, and essential advances in femtosecond laser direct-write 3D multi-photon lithography (MPL, also known as two-photon or multi-photon polymerization) are being made. Micro-optics realized via MPL emerged a decade ago and the field has exploded during the last five years. Impressive findings have revealed its potential for beam shaping, advanced imaging, optical sensing, integrated photonic circuits, and much more. This is suppo...

High-Transparency 3D Micro-Optics of Hybrid-Polymer SZ2080™ Made via Ultrafast Laser Nanolithography and Atomic Layer Deposition

“…LDW commonly exploits 2-photon polymerization (2PP) or other photo-excitation mechanisms of prepolymers, induced by non-linear absorption of highly focused laser radiation. Currently, it is the only method to produce truly free-form 3D sub-100 𝜇m structures, therefore extremely advantageous for the fabrication of complex micro-optics [3]. Recently, functional 2.5 and 3D optical elements, such as aspheric, suspended lenses, waveguides, and fully functional multi-lens objectives were demonstrated [4][5][6].…”

Microlenses fabricated by two-photon laser polymerization for cell imaging with non-linear excitation microscopy

“…Among additive manufacturing (AM) techniques, the only suitable technology to achieve this goal is two-photon polymerization (2PP). [18][19][20][21][22] Once the optical design is defined and tested, the solution for a widespread use of the implantable micro-optics would be the use of high throughput techniques like nano-imprint lithography (NIL), starting from high resolution molds fabricated by 2PP.…”

White emission in 3D-printed phosphor microstructures

“…10 The development of 3D phosphors emitting in other primary colours and white is a step forward to realizing additive colour synthesis within complex architectures of relevance in integrated optics or light-emitting sources. 8 Further, the biocompatibility of ZrO 2 could also prospectively permit their use in biomedical imaging or sensing. 14,15 In this study, we present the additive manufacturing (AM) of ZrO 2 doped structures emitting in red (Eu 3+ ), green (Tb 3+ ), blue (Tm 3+ ), and white (Eu 3+ , Tb 3+ , and Tm 3+ ).…”

“…7 Upon excitation, phosphorous materials are highly-efficient emitters of narrowly defined radiation that find a broad range of applications, such as microoptics. 8 Low phonon energy ceramics are typically preferred, as they promote higher RE 3+ optical transitions quantum efficiencies by reducing non-radiative decay rates. 9 Sufficient RE 3+ solubility is required to prevent dopant clustering.…”

“…10 The development of 3D phosphors emitting in other primary colours and white is a step forward to realizing additive colour synthesis within complex architectures of relevance in integrated optics or light-emitting sources. 8 Further, the biocompatibility of ZrO 2 could also prospectively permit their use in biomedical imaging or sensing. 14,15…”