High-performance optical spectroscopy integrated into hand-held platforms, especially smartphones, is vital for numerous consumer applications. However, optical spectrometers pose a challenge for miniaturization due to the fundamental limitations of small- and angle-dependent light dispersion. We introduce a new bioinspired light dispersion technology combining disordered scattering nanostructures with ordered Bragg resonances to achieve an ultralarge and angle-independent dispersion. We demonstrate an ultracompact spectrometer using the bioinspired dispersive element enabling simultaneous wide-angle visible imaging and near-infrared spectroscopy on a single conventional complementary metal-oxide-semiconductor image sensor. This approach reduces dispersion-based spectrometer device thickness or total track length below 5 mm with an angular tolerance of 30 degrees, sub-5 nm spectral resolution, and 200 nm bandwidth, enabling hand-held and smartphone-integrated spectroscopy and opening up a new way to achieve high-performance mobile sensing and detection.

The generation of high-purity localized trions, dynamic exciton-trion interconversion, and their spatial modulation in two-dimensional (2D) semiconductors are building blocks for the realization of trion-based optoelectronic devices. Here, we present a method for the all-optical control of the exciton-to-trion conversion process and its spatial distributions in a MoS2 monolayer. We induce a nanoscale strain gradient in a 2D crystal transferred on a lateral metal-insulator-metal (MIM) waveguide and exploit propagating surface plasmon polaritons (SPPs) to localize hot electrons. These significantly increase the electrons and efficiently funnel excitons in the lateral MIM waveguide, facilitating complete exciton-to-trion conversion even at ambient conditions. Additionally, we modulate the SPP mode using adaptive wavefront shaping, enabling all-optical control of the exciton-to-trion conversion rate and trion distribution in a reversible manner. Our work provides a platform for harnessing excitonic quasiparticles efficiently in the form of trions at ambient conditions, enabling high-efficiency photoconversion.

Bioinspired Nanostructures How can glasswing butterflies make contact lenses more functional? In article number 2205113, Radwanul Hasan Siddique, Hyuck Choo, and co‐workers have shown that integrating glasswing butterfly wing‐inspired nanostructures on a scleral lens can enhance visibility, block UV radiation, reduce bacterial infection and add sensing capabilities too! Such bioinspired scleral lens sensors can detect lysozyme and lactoferrin in whole human tears for chronic dry eye disease management.

Metasurfaces provide versatile platforms for arbitrary wavefront shaping with designer optical response such as amplitude, phase, and polarization at the deep subwavelength regime. Tunable metasurfaces can bring additional degree of freedom in terms of the time-dependent change of these responses, which can pave a way for novel applications such as wide-field-of-view holographic display and light detection and ranging (LiDAR). In this talk, we present the all-dielectric metasurface array that can modulate the phase of light above 270° in reflection with high reflectivity over 60% as a function of the individually applied voltage in the near infrared regime.

This special issue highlights the collaboration between universities and industries in materials research in South Korea. Due to the extensive scope of the ongoing collaboration, we are focusing on a specific topic where university–industry collaboration in South Korea is particularly strong and involves the largest industrial partners. The contributions in this issue are intended to be co-authored by both industry and university representatives. Ad-ditionally, a few industry-specific articles have been included to showcase the industry’s vision for such collaborations. Given that the emphasis of this special issue is significant to both Advanced Materials and Advanced Materials Technology , we have combined the two to feature a broader range of collaborations and these issues are now combined as one virtual special issue. In this context, we introduce the backgrounds and evolution of the materials program in South Korea, highlighting the unique research ecosystem that has fostered a strong alliance with industries. Furthermore, we aim to present a vision for the future of materials programs, considering the collaboration between industries and universities. TheLatin phrase “Per ardua ad astra,” meaning “through ad-versity to the stars,” aptly describes the remarkable achievements in materials research in South Korea, a country that has faced poverty, war (1950–1953 Korean war), division, limited technological advancement, and insufficient natural resources. The growth of materials research in South Korea aligns with its dynamic

Recent advancements in nanotechnology raise the feasibility of a miniaturized, portable Raman spectrometer with promising applications such as material identification, food safety monitoring, and health care. Miniaturizing Raman spectrometers has remained a challenge owing to the inevitable weakness of Raman signals and the conflict between small size and spectral resolution. In this study, we present a portable mini-Raman spectrometer comprising a complementary metal–oxide semiconductor (CMOS) image sensor (CIS) integrated with an array of filter sets, a confocal probe, and a laser diode that successfully meets the miniaturization challenge. We also report successful measurement of Raman spectra using the CIS-based mini-spectrometer, measuring cyclohexane liquid, tylenol pills, and vitamin-C pills with high spectral resolution. Our mini-Raman spectrometer, which can measure Raman signals in a two-dimensional (2D) image format in a single-shot, can be embedded into commercial mobile phones and transformed into a promising Raman camera.

Augmenting contact lenses with sensing capabilities requires incorporating multiple functionalities within a diminutive device. Inspired by multifunctional biophotonic nanostructures of glasswing butterflies, a nanostructured scleral lens with enhanced optical, bactericidal, and sensing capabilities is reported. When used in conjunction with a smartphone-integrated Raman spectrometer, the feasibility of point-of-care applications is demonstrated. The bioinspired nanostructures made on parylene films are mounted on the anterior and posterior side of a scleral lens to create a nanostructured lens. Compared to unstructured parylene, nanostructured parylene minimizes glare by 4.3-fold at large viewing angles up to 80 o . When mounted on a scleral lens, the nanostructures block 2.8-fold more ultraviolet (UVA) light while offering 1.1-fold improved transmission in the visible regime. Furthermore, the nanostructures exhibit potent bactericidal activity against Escherichia coli , killing 89% of tested bacteria within 4 h. The same nanostructures, when gold-coated, are used to perform rapid label-free multiplex detection of lysozyme and lactoferrin, the protein biomarkers of the chronic dry eye disease, in whole human tears using drop-coating deposition Raman spectroscopy. The detection of both proteins in whole human tear samples from different subjects using the nanostructured lens produced excellent correlation with commercial enzyme-based assays while simultaneously displaying a 1.5-fold lower standard deviation.

Beam steering devices can be used for various applications such as light detection and ranging and free space optical communication. The conventional methods for the beam steering are based on the mechanical rotation of mirrors and cause bulk form-factor and limited operation speed. The metasurfaces are arrays of dielectric or metallic antennas that can tailor the optical properties such as amplitude and phase at the deep subwavelength range. Here, we present the all-dielectric metasurface that can modulate the reflection phase >270° with high reflectivity >60% as a function of the individually applied voltage in the near infrared regime.

Photonic crystal (PhC) phosphor is a paradigm-shifting structural platform that the authors’ group has developed. In this study, two major changes are introduced to the existing two-dimensional PhC phosphor: an increase in the refractive index contrast by replacing the PhC backbone material and the planarization of phosphor surface by the squeegee method. Compared with the reference phosphor, the upgraded PhC phosphor exhibits ~59 times enhanced absorption (simulated) and ~7 times enhanced phosphor emission (experimental). Although already impressive, the huge gap between theory and experiment indicates ample room for further improvement through, for example, the refinements in device fabrication.

The optical phased array has been developed to realize solid-state optical beam steering following the advent of silicon photonics. Thus far, its feasibility has lacked either steering quality or optical efficiency, and its optimal design still remains unknown. Herein, we propose a scalable and wavelength-independent phased array design methodology that achieves steering quality and optical efficiency. This novel design methodology is based on a special aperiodicity from number theory of a complete residue system that is fundamentally suited for phasor cancellation for the desired array sparsity. A specific design derived based on this methodology was implemented in silicon with 128 phase-controlled antennas in the O band, and it was experimentally verified in a two-dimensional steering demonstration that featured a record-high beam-forming efficiency (>30%) and a high-grating-lobe suppression (>10 dB) over a field-of-view of 40 ⅹ 7.2°. This optical efficiency improved by at least 250% compared with prior art.

Measuring, recording and analyzing spectral information of materials as its unique finger print using a ubiquitous smartphone has been desired by scientists and consumers. We demonstrated it as drug classification by chemical components with smartphone Raman spectrometer. The Raman spectrometer is based on the CMOS image sensor of the smartphone with a periodic array of band pass filters, capturing 2D Raman spectral intensity map, newly defined as spectral barcode in this work. Here we show 11 major components of drugs are classified with high accuracy, 99.0%, with the aid of convolutional neural network (CNN). The beneficial of spectral barcodes is that even brand name of drug is distinguishable and major component of unknown drugs can be identified. Combining spectral barcode with information obtained by red, green and blue (RGB) imaging system or applying image recognition techniques, this inherent property based labeling system will facilitate fundamental research and business opportunities.

We simulate characteristics of colour-routing image sensors revealing higher peak-SNR and color fidelity with slightly degraded spatial resolutions compared to those of conventional sensors. To compensate, we propose the rapid resolution-restoring demosaic algorithm for colour-routers.

The ongoing pandemic and increasing frequency of infectious disease outbreaks due to climate change, urbanization, and global human migration have put great focus on nucleic acid amplification‐based diagnostic technologies (NAAT). These methods can provide gold standard accuracy and sensitivity, and their widespread availability at the point‐of‐care is crucial for managing the spread of pathogens in human and animal populations, as well as for environmental surveillance. However, so far the reach of NAAT‐based platforms has mostly remained limited to centralized facilities in the hand of trained workers, causing great distress in times of need. In this review, the current state‐of‐the‐art research, as well as, commercial diagnostic products, is highlighted, their performances are discussed, and the role of academic‐industrial collaborations in developing the next generation of breakthrough technologies is emphasized. It is envisioned that with these collaborations, the next generation of autonomous, affordable, and mobile NAAT devices can be developed, for a broad range of targets, and for providing truly democratized access to NAAT diagnostics for the global population in the future.

The commoditization of photonics would be possible only with the development of photonic integrated circuits and appropriate volume applications that require them. As such an application, a light detection and ranging(LiDAR) sensor has recently been in strong demand from various applications including autonomous driving. In terms of technology, as silicon photonics enters an industrial phase and begins to utilize the existing CMOS infrastructure, photonic integrated circuits are also expected to enter a virtuous cycle of volume and cost. This work outlines the current status of LiDAR research using the silicon photonics platform in Samsung. Based on the III/V-on-Si technology, Samsung's platform enables the development of chip-scale LiDAR that integrates all photonic devices such as wavelength-tunable laser, semiconductor optical amplifier, and custom optical phased array. With the LiDAR chip in the core, a palm-top LiDAR module prototype including control and signal processing circuits is also presented. Then, initial application-level attempts in autonomous driving are presented in the hope of pathfinding towards the LiDAR commoditization, and more broadly, commoditization of photonics.

The CMOS industry has been expecting silicon photonics to provide photonic and electro-photonic integrated circuits based on the CMOS processes and infrastructures for scalability of incumbent technology evolutions and creation of novel technologies. However, the compatibility with the legacy CMOS has been compromised with the development convenience of early silicon photonics in that the specialty silicon-on-insulator substrates have been widely used as integration platforms. Since this specialty substrate may hinder the photonics integration with legacy volume products later, a legacy-friendly integration platform with a generic bulk-silicon substrate has been developed for better compatibility. This paper overviews the bulk-silicon photonics platform born for DRAM integration, upgraded with III/V-on-bulk-Si lasers, and transplanted to LiDAR applications requiring the virtuous cycle of cost and volume. The photonics integration with DRAM was to resolve the speed-capacity trade-off in the DRAM interconnects, and technical feasibility as well as lessons learned from the integration attempt are reviewed. The bulk-silicon device performance approaches that of silicon-on-insulator devices with the thermal advantage of ∼40-% lower thermal impedance and the optical disadvantage of ∼0.4-dB/mm higher waveguide loss. In the LiDAR applications, detection performance up to ∼20 m at 20 fps by a single-chip scanner integrating tunable laser, semiconductor optical amplifiers, and optical phased array are presented with future outlooks.

We design color-routing nanostructures that can spectrally guide light into a Bayer array. To demonstrate, we fabricated 1.0-0.5 um pixel Bayer arrays composed of TiO 2 nanoposts and imaged the color-routing focal plane under white light illumination.

Miniaturization of optical spectrometers has recently drawn a lot of attention due to the increasing needs of portable characterization systems for scientific, industrial, and consumer applications. At the same time, smartphones have technically evolved to become an everyday, ubiquitous device that provides numerous useful applications to consumers. Combining optical spectrometer and smartphone could lead to an explosion of new applications, especially in healthcare, biometrics, and food inspections, and change our daily life, making it more convenient, independent, and hyper-personalized. In this work, we have developed a smartphone spectrometer in the visible and near infrared (NIR) ranges by directly integrating a 2 dimensional periodic array of band-pass filters on top of the smartphone’s image sensor. Each band pass filter is a silicon resonator consisting of a pair of Si/SiO₂ distributed Bragg reflectors (DBR), where each resonator’s transmitting wavelength is set by adjusting the thickness of the center Si layer. The DBR contains alternating, vertically-stacked TiO2 and SiN films with variable thicknesses while the top and bottom of the DBR were made of Al and Cu or Al reflectors for the visible and NIR ranges, respectively. The fabrication process was completely CMOS-compatible. Using this smartphone spectrometer, we have proposed the concept of artificial-intelligence-powered spectral barcode for material identification and successfully demonstrated its use in drug identification. The accuracy of correctly identifying the type of drugs was ~99%. In addition, the smartphone spectrometer has also proven to correctly distinguish beef into three different classes according to the freshness.

Understanding and controlling the nanoscale transport of excitonic quasiparticles in atomically thin two-dimensional (2D) semiconductors are crucial to produce highly efficient nano-excitonic devices. Here, we present a nanogap device to selectively confine excitons or trions of 2D transition metal dichalcogenides at the nanoscale, facilitated by the drift-dominant exciton funneling into the strain-induced local spot. We investigate the spatiospectral characteristics of the funneled excitons in a WSe2 monolayer (ML) and converted trions in a MoS2 ML using hyperspectral tip-enhanced photoluminescence imaging with <15-nm spatial resolution. In addition, we dynamically control the exciton funneling and trion conversion rate by the gigapascal-scale tip pressure engineering. Through a drift-diffusion model, we confirm an exciton funneling efficiency of ∼25% with a significantly low strain threshold (∼0.1%), which sufficiently exceeds the efficiency of ∼3% in previous studies. This work provides a previously unexplored strategy to facilitate efficient exciton transport and trion conversion of 2D semiconductor devices.

Abstract Tunable metasurfaces can change the optical properties of incident light at will such as amplitude, phase, and polarization in a time-dependent fashion. Ultrafast switching speed and the ability for the pixel size reduction of the tunable metasurface can allow various applications such as light detection and ranging, interferometric sensors, and free space optical communications, to name a few. Although there have been successful demonstrations of the wavefront shaping using the tunable metasurface, the implementation of the two-dimensional metasurface pixel array that can be individually addressed in the optical frequency regime still remains challenging. Here, we present the experimental demonstration of the two-dimensional beam steering with the metasurface array by the binary phase grating in the infrared regime. The metasurface unit cell is composed of metal–dielectric–oxide structure with the indium tin oxide as an active layer, which is modulated by using the top fan-out electrodes. The metasurface array is two-dimensionally pixelated and has the phase change above 137° in the infrared regime.

We present a real-time light detection and ranging (LIDAR) imaging by developing a single-chip solid-state beam scanner. The beam scanner is integrated with a fully functional 32-channel optical phased array, 36 optical amplifiers, and a tunable laser at central wavelength ~1310 nm, all on a 7.5 x 3 mm^2 single chip fabricated with III-V on silicon processes. The phased array is calibrated with self-evolving genetic algorithm to enable beam forming and steering in two dimensions. Distance measurement is performed with a digital signal processing that measures the time of flight (TOF) of pulsed light with a system consisting of an avalanche photodiode (APD), trans-impedance amplifier (TIA), analog-digital converter (ADC), and a processor. The LIDAR module utilizing this system can acquire point cloud images with 120 x 20 resolution with a speed of 20 frames per seconds at a distance up to 20 meters. This work presents the first demonstration of a chip-scale LIDAR solution without any moving part or bulk external light source or amplifier, making an ultra-low cost and compact LIDAR technology a reality.