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Materials Science in Additive Manufacturing Additive manufacturing of active optics

These methods also involve intricate lithography, etching, unprecedented design flexibility, high precision, and the
and deposition processes, making them time-consuming seamless integration of diverse materials into complex 3D
and resource-intensive. photonic systems. 3-5
Unlike traditional techniques, additive manufacturing In the following sections, we systematically explore the
enables the direct, layer-by-layer construction of complex criteria for beam control in active 3D optical structures
three-dimensional (3D) structures without the need for (Section 2), delving into wavelength, directional, and span
molds or extensive post-processing. This approach provides angle control to optimize light manipulation. Section 3
unprecedented design freedom and precise control over reviews the diverse active materials essential for light-
beam properties, such as propagation direction, angular emitting 3D optics, covering polymers, metals, ceramics,
distribution, and emission wavelength. Arbitrarily shaped QDs, and nanocomposites. In Section 4, we examine the
3D structures support advanced functionalities, including additively manufactured 3D active optical structures,
anisotropic light control, enhanced energy management, from refractive and diffractive optics to metasurfaces,
and the seamless integration of refractive, diffractive, and highlighting innovations in optoelectronics and photonic
metasurface elements. These capabilities are critical for circuit integration. Section 5 provides an in-depth look
applications requiring miniaturization and tailored optical at the additive manufacturing techniques enabling these
effects, such as 3D imaging, endoscopy, and spectroscopy. advancements, followed by a discussion of emerging trends
1,2
Furthermore, the incorporation of diverse materials – such and future directions in Section 6.
as polymers, ceramics, and composites – broadens the
scope of functionality, enabling innovations in photonic 2. Beam control performance criteria for
circuit design, optical computing, and high-precision active 3D optical structures
metrology.
To fully harness the capabilities of light-emitting 3D
In the past decade, significant progress has been made in structures, precise control over beam characteristics is
the development of additive manufacturing for fabricating essential. This is particularly crucial in applications like 3D
light-emitting devices. Technologies such as inkjet cellular imaging, biomedical endoscopy, and advanced
6
7
printing, fused deposition modeling (FDM), direct ink spectroscopy, where factors such as beam direction,
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8
writing (DIW), stereolithography (SLA), and selective laser angular distribution, emission point, and wavelength
10
12
11
sintering (SLS) have been adapted to produce active optical play pivotal roles. These criteria directly impact key
components. Each method operates on distinct principles: performance metrics, including resolution, contrast, and
inkjet printing uses droplet-based deposition for precise depth penetration, as shown in Figure 1 and summarized
multi-material designs; FDM employs filament extrusion in Table 1. 1,2,13-16
and layer-by-layer deposition; DIW utilizes pressurized
extrusion of viscous inks for flexible material integration; For instance, as shown in Figure 1A and B, in 3D cellular
SLA relies on laser-activated photopolymerization imaging, it is essential to have fine control over the beam
for high-resolution structuring; and SLS uses heat- propagation direction and angular emission to achieve
induced laser sintering of powdered materials for robust, accurate depth imaging and reduce scattering effects.
complex geometries. These techniques collectively enable Similarly, biomedical endoscopy requires light sources that

Table 1. Beam performance criteria, importance, and application examples
Performance criteria Importance Application examples
Wavelength control • Adjustability between penetration depth, and spatial resolution • Dynamic cellular processes imaging
• Selective visualization • Labeled imaging
• Spectroscopy
Emission direction control • Structured beam generation • Structured illumination microscopy
• Light path optimization in complex optical system • Optical tweezers
• Precise control of focal point • Holographic 3D display
• Spatial light modulator
• 3D display
Span angle control • Adjustability between field‑of‑view coverage and imaging resolution • LiDAR
• Active beam steering • Display application
• Spatial light modulator
• Phototonic‑crystal surface‑emitting lasers
Abbreviation: LiDAR: Light detection and ranging.

Volume 3 Issue 4 (2024) 2 doi: 10.36922/msam.5748