The interaction between light and matter is fundamental and critical to numerous technologies that define present-day modern society and emerging innovations that promise to revolutionize our future. The controlled generation of light from solid-state materials is the backbone of lasers, digital screens, and quantum communications, the latter being a nascent but emerging area of an envisioned imminent quantum revolution. Sophisticated light source designs have had a tremendous impact on the development of advanced materials characterization techniques (e.g., time- and angle-resolved photoemission spectroscopy and attosecond spectroscopy) and are prolific in the newly developed instrumentation to probe biological systems and processes. The latest generations of commercial, industrial, medical, and defense technologies (e.g., high-resolution displays, augmented reality devices, and integrated photonic chips) rely on the design of new materials and nanoscale systems that can efficiently control light. These new material systems must also be complemented with nanofabrication techniques that synergize precision nanoscale control with scalability. Beyond generation and control, the process of detecting light and converting it into electrical signals using materials with strong light–matter interactions is also essential to many high-impact technological areas. Broadly speaking, these areas include medical diagnostics, photovoltaics, scientific instrumentation, imaging (e.g., infrared imagers), and sensing (e.g., for light detection and ranging as well as terahertz imaging). Countless modern commercial, industrial, and scientific technologies upon which we rely and many that will shape our future are rooted in efficiently harnessing the interaction between light and matter.

Although the technological impact of the field may give the impression that it is very mature, significant breakthroughs in light–matter interactions continue to emerge at a rapid pace, resulting in a sustained and continuous push to new scientific and technological frontiers. Novel material systems catalyze the discovery and development of new states in matter that strongly interact with light. As a result, new degrees of freedom become available to engineer and enhance light–matter interactions, which, in turn, present new opportunities to optimize the performance of optical devices and materials. The new material systems are accompanied by innovative fabrication/nano-assembly processes that facilitate tailoring and engineering light–matter interactions at smaller and smaller length scales that are ideal for chip-scale photonics. Along with new materials, state-of-the-art calculations predict emergent light–matter interactions that can arise from precise nanoscale sculpting and fabrication. Inventive processes for materials growth and nanofabrication techniques open viable routes to realizing such increasingly sophisticated optical systems that are able to capitalize on nanoscale engineering and offer scalability for technological relevance. Ultimately, these advances add new materials, theoretical tools, fabrication and synthesis techniques, and new scientific concepts to the toolbox available to researchers and engineers to continue to harness light–matter interactions.

The “Light and Matter Interactions” special topic in APL Materials brings timely attention to this emerging research field as it continues to grow at a rapid pace, reporting exciting discoveries on what is essentially a daily basis. The umbrella of light and matter interactions is relatively broad and covers many topics, most of which are appealing to a wide audience of researchers from a diverse range of fields. The special issue provides an opportunity for these researchers to overview the field from one vantage point and review eleven impactful studies that represent new frontiers of research that are rooted and deeply relevant to advances in harnessing light and deepening our understanding of the interaction between light and matter. The coverage of these studies is broad, and the special topic issue will hopefully renew an appreciation for how interdisciplinary this research area is and for the potential of future groundbreaking advances to emerge from dovetailing research in two areas that, may at first, seem disparate.

Four of the investigations that are reported in the special topic highlight how two-dimensional (2D) materials are advancing light–matter interactions ultimately toward new scalable photonic technologies and new optical materials. In two of these studies, the interaction between light and 2D charge density wave phenomena features most prominently. The study of Joshi et al.1 reports the observation and detailed characterization of a new optically emissive state in a heterostructure composed of a 2D semiconductor that is directly interfaced to a 2D charge density wave material. The state results from the hybridization of excitons and 2D charge density waves. Moving in the direction of optical devices, Li and Naik2 report that optical switching of charge density wave domains contrasts with what is achievable with electrical stimulation alone. In the third study on 2D materials, Pavlidis et al.3 combine two sophisticated near-field optical and scanning probe techniques with refined materials synthesis to demonstrate that hyperbolic phonon polaritons (potential hybrid light–matter states for integrated photonic technologies) in 2D hexagonal boron nitride (hBN) have long lifetimes and accordingly elongated propagation distances. However, 2D materials will be of limited use if scalable synthesis techniques for large area films are not developed, and Jin et al.4 provide new insights on the scalable epitaxial growth of hBN on a graphene substrate in the fourth study.

An additional four studies in the special topic issue focus on new materials beyond 2D systems for photonic and optical devices. A new quantum dot structure that has a gradient alloy composition and improves the performance of photodetectors that are based on quantum dots is reported by Dan et al.5 Yoshioka et al.6 report on the enhancement of the second-order nonlinearity of scandium-doped aluminum nitride (AlN) that is recognized as a CMOS-compatible material. The CMOS compatibility is appealing because it means that these thin films with large nonlinear optical responses can readily be adopted into established fabrication processes for Si-based integrated photonics. de Clermont-Gallerande et al.7 performed comprehensive materials analysis of tellurium oxide (TeO2) glass to understand how doping of neodymium (Nd) ions affects its structural, thermal, and mechanical properties. TeO2 glasses are promising materials for photonic applications due to their high refractive indices and large third-order optical nonlinear responses. Additionally, as a great example of the breadth of the field, Yee et al.8 report a detailed study of the light–matter interaction mechanism by which pyrolytic graphite that is levitated in a magnetic trap is mechanically translated by optical irradiation. Despite the extensive nature of the study, the authors point out that there is still much to be understood about this particular light–matter interaction, motivating future investigations.

Last, but certainly not least, three studies in the special topic report theoretical and computational studies that predict designer nanoscale systems to manipulate and control light in novel ways. The design and predicted performance of a dielectric metasurface that is capable of a spatially inhomogeneous polarization control of mid-infrared light is reported by Zalogina et al.,9 and its performance as a vortex retarder is assessed. Li et al.10 report a silicon (Si)-based metasurface that leverages unique hybrid light–matter states (spoof surface plasmons) for enhanced sensing capabilities in the demanding terahertz frequency regime. Finally, a sophisticated three-dimensional (3D) metastructure of photonic nanotubes is analyzed by Abrashuly and Valagiannopoulos11 and is predicted to behave as a photonic memory element where its optical response strongly depends upon the nature of the light that previously illuminated it.

In summary, the special topic on light and matter interactions in APL Materials provides an exciting snapshot of eleven studies that exquisitely represents the vibrancy and breadth of research and development in this field. From this breadth, the interdisciplinarity of the field is clear, and the studies demonstrate how the field advances from research spanning theoretical and computational studies, new material synthesis techniques, hierarchical nano-assembly of materials and characterization of the resulting hybrid states, and nanofabrication and characterization of prototypes of new optical devices. By no means is this special topic issue comprehensive. Such a special issue would need to consist of hundreds or perhaps thousands of articles. However, we hope that this snapshot inspires our broad and diverse research community in light–matter interactions to consider the field in its entirety, appreciate its interdisciplinarity, and consider new opportunities that may be outside of individual silos but hold promise to drive technological innovation and scientific discovery in the field.

N.J.B., C.A., and L.Y. thank all of the authors who contributed to this special topic issue. They also greatly appreciate the support from journal editors Professor Wei Li and Professor Judith L. Driscoll, as well as the editorial support staff members Katherine VanDenburgh and Jessica Trudeau.

The authors have no conflicts to disclose.

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,
D. J.
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J.
Paglione
,
A.
Davydov
,
I.
Žutić
, and
P. M.
Vora
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W.
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G. V.
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G.
Pavlidis
,
J. J.
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Folland
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J. H.
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J. D.
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Centrone
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Dan
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Wu
,
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Wang
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Q.
Zhao
,
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Liu
,
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Li
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9
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081117
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V.
Yoshioka
,
J.
Lu
,
Z.
Tang
,
J.
Jin
,
R. H.
Olsson
 III
, and
B.
Zhen
, “Strongly enhanced second-order optical nonlinearity in CMOS-compatible Al1−xScxN thin films,”
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9
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101104
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J.
de Clermont-Gallerande
,
D.
Taniguchi
,
M.
Colas
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P.
Thomas
, and
T.
Hayakawa
, “Influence of Nd3+ modifying on 80TeO2–xZnO–(20 − x)Na2O ternary glass system,”
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9
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Yee
,
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ElBidweihy
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A.
Zalogina
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Kivshar
,
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Shadrivov
, and
S.
Kruk
, “Mid-infrared cylindrical vector beams enabled by dielectric metasurfaces,”
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9
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X.
Li
,
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Wang
,
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X.
Hou
,
D.
Yan
,
G.
Qiu
,
S.
Guo
,
W.
Zhou
, and
J.
Li
, “Terahertz spoof surface plasmon sensing based on dielectric metagrating coupling,”
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9
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11.
A.
Abrashuly
and
C.
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