Aberration Theory of a Flat, Aplanatic Metalens Doublet and the Design of a Meta-Microscope Objective Lens.

A theoretical approach for reducing multiple monochromatic aberrations using a flat metalens doublet is proposed and verified through ray tracing simulations. The theoretical relation between the Abbe sine condition and the generalized Snell's law is revealed in the doublet system. Starting from the Abbe aplanat design, minimization conditions of astigmatism and field curvature are derived. Based on the theory, a metalens doublet is semi-analytically optimized as a compact, practical-level meta-microscope objective lens working for a target wavelength. The proposed approach also reveals how to reduce lateral chromatism for an additional wavelength. The design degree of freedom and fundamental limits of the system are both rigorously analyzed in theory and verified through ray tracing simulations. It is expected that the proposed method will provide unprecedented practical opportunities for the design of advanced compact microscopic imaging or sensing systems.

Pilot Study About the Effects of the Soma Experiencing Motion (Soma e-Motion) Program on Interoceptive Awareness and Self-Compassion.

OBJECTIVE: The purpose of this study was to examine the effects of the Soma experiencing motion (Soma e-motion) program on interoceptive awareness and self-compassion among novices. METHODS: A total of 19 adults (clinical group=9, non-clinical group=10) participated in the intervention. Psychological and physical changes after program were qualitatively analyzed using in-depth interviews. The Korean Multidimensional Assessment of Interoceptive Awareness (K-MAIA) and the Korean version of the Self-Compassion Scale (K-SCS) were used as quantitative measures. RESULTS: The non-clinical group showed statistically significant differences in the K-MAIA scores (z=-2.805, p<0.01) and K-SCS scores (z=-2.191, p<0.05); however, the clinical group showed no significant differences (K-MAIA: z=-0.652, p>0.05; K-SCS: z=-0.178, p>0.05). According to the in-depth interviews, the results of the qualitative analysis were categorized into five dimensions (psychological and emotional, physical, cognitive, behavioral, and aspects participants found challenging and needs improvement). CONCLUSION: The Soma e-motion program was feasible for improving interoceptive awareness and self-compassion in the non-clinical group. However, further research is needed to investigate the clinical efficacy of the Soma e-motion program for clinical group.

Design of highly perceptible dual-resonance all-dielectric metasurface colorimetric sensor via deep neural networks.

Colorimetric sensing, which provides effective detection of bio-molecular signals with one's naked eye, is an exceptionally promising sensing technique in that it enables convenient detection and simplification of entire sensing system. Though colorimetric sensors based on all-dielectric nanostructures have potential to exhibit distinct color variations enabling manageable detection due to their trivial intrinsic loss, there is crucial limitation that the sensitivity to environmental changes lags behind their plasmonic counterparts because of relatively small region of near field-analyte interaction of the dielectric Mie-type resonator. To overcome this challenge, we proposed all-dielectric metasurface colorimetric sensor which exhibits dual-resonance in the visible region. Thereafter, we confirmed with simulation that, in the elaborately designed dual-Lorentzian-type spectra, highly perceptible variations of structural color were manifested even in minute change of peripheral refractive index. In addition to verifying physical effectiveness of the superior colorimetric sensing performance appearing in the dual-resonance type sensor, by combining advanced optimization technique utilizing deep neural networks, we attempted to maximize sensing performance while obtaining dramatic improvement of design efficiency. Through well-trained deep neural network that accurately simulates the input target spectrum, we numerically verified that designed colorimetric sensor shows a remarkable sensing resolution distinguishable up to change of refractive index of 0.0086.

Qualitative and Quantitative Analyses of Donor Site Morbidity Following a Graft of the Acellular Dermal Matrix Versus Primary Fascial Repair After ALT Flap Harvesting.

BACKGROUND: The anterolateral thigh (ALT) flap is one of the most useful flaps in reconstruction because of its reliability, large skin flap territory, and versatility. The relatively small number of side effects is a common reason for preferring this flap. Primary repair is usually performed at the donor site closure; however, this requires substantial tension and causes many donor site morbidities, including pain. We attempted to use acellular dermal matrix graft to overcome these problems. METHODS: We analyzed a total of 41 cases (41 flaps) in this study. Among these flaps, we conducted donor fascia suture with artificial dermis in 20 cases (study group) and primary fascial suture in 21cases (control group). Post-operative ambulation recovery times, pain scores, drainage removals, and wound problems of the donor site were recorded. RESULTS: There were no serious complications, including infection, at the donor sites of all 41 cases. Of 20 cases using the acellular dermal matrix, seroma occurred in 2 cases and partial skin necrosis occurred in 2 cases. In 1 case of skin necrosis, the acellular dermal matrix was removed. However, in comparison to the control group, the group using the artificial dermis recovered ambulatory ability 3.9 days earlier and had a 1.8-point lower visual analogue scale score 5 days post-operatively. CONCLUSIONS: Our study suggested that, if used selectively, the acellular dermal matrix may play an effective role in donor site closure in cases with procedures involving the ALT flap.

HISTORIQUE: Le lambeau antérolatéral de la cuisse est l'un des plus utiles pour la reconstruction à cause de sa fiabilité, de son grand territoire et de sa polyvalence. Le relativement petit nombre d'effets secondaires est une raison courante pour le préférer. La réparation primaire est généralement effectuée à la fermeture du site du donneur, mais il faut une tension importante, ce qui entraîne de nombreuses morbidités au site du donneur, y compris la douleur. Les chercheurs ont tenté d'utiliser une greffe de la matrice dermique acellulaire pour vaincre ces problèmes. MÉTHODOLOGIE: Les chercheurs ont analysé un total de 41 cas (41 lambeaux) dans cette étude. De ce nombre, ils ont effectué une suture du fascia du donneur à l'aide de derme artificiel dans 20 cas (groupe d'étude) et une suture fasciale primaire dans 21 cas (groupe témoin). Ils ont également pris note de la durée de convalescence ambulatoire postopératoire, des scores de douleur, de la désinstallation du drainage, et des problèmes de plaie au site du donneur. RÉSULTATS: Il n'y a pas eu de complications graves, y compris l'infection, aux sites des donneurs des 41 cas. On a observé un sérome dans deux des 20 cas faisant appel à la matrice dermique acellulaire, et une nécrose cutanée partielle dans également deux cas. Dans l'un des cas de nécrose cutanée, la matrice dermique acellulaire a dû être retirée. Cependant, comparativement au groupe témoin, le groupe qui a utilisé le derme artificiel a récupéré sa capacité ambulatoire 3,9 jours plus rapidement et présentait un score de 1,8 point de moins à l'échelle analogique visuelle cinq jours après l'opération. CONCLUSIONS: Selon la présente étude, la matrice dermique acellulaire utilisée sélectivement peut jouer un rôle efficace à la fermeture du site du donneur dans les cas d'intervention faisant appel au lambeau antérolatéral de la cuisse.

A Mixed-Methods Study Protocol for Soma Experiencing Motion Program (Soma e-motion Program): The Effectiveness of Contemplative Movement for Emotion Regulation.

Somatics refers to body work and movement study that emphasize internal perception and experience. Recently, a new perspective has emerged that views somatics-based techniques as a kind of mindful movement. Somatic techniques as contemplative movement can improve emotional regulation ability through improvement of body awareness or interoception. Based on this background, the present study attempts to develop a somatics based program suitable for a group of clinical patients suffering from emotional dysregulation. This study plans to collect quantitative and qualitative data in order to clarify how interoception and the related emotional regulation ability change after the program. These findings will help to explore whether the somatics technique has potential as an emotion regulation program in the future. In addition, the results are expected to contribute to finding an alternative treatment modality for patients who have not achieved a sufficient effect with conventional psychotherapy.

Dielectric Metalens: Properties and Three-Dimensional Imaging Applications.

Recently, optical dielectric metasurfaces, ultrathin optical skins with densely arranged dielectric nanoantennas, have arisen as next-generation technologies with merits for miniaturization and functional improvement of conventional optical components. In particular, dielectric metalenses capable of optical focusing and imaging have attracted enormous attention from academic and industrial communities of optics. They can offer cutting-edge lensing functions owing to arbitrary wavefront encoding, polarization tunability, high efficiency, large diffraction angle, strong dispersion, and novel ultracompact integration methods. Based on the properties, dielectric metalenses have been applied to numerous three-dimensional imaging applications including wearable augmented or virtual reality displays with depth information, and optical sensing of three-dimensional position of object and various light properties. In this paper, we introduce the properties of optical dielectric metalenses, and review the working principles and recent advances in three-dimensional imaging applications based on them. The authors envision that the dielectric metalens and metasurface technologies could make breakthroughs for a wide range of compact optical systems for three-dimensional display and sensing.

Full-Color-Tunable Nanophotonic Device Using Electrochromic Tungsten Trioxide Thin Film.

Color generation based on strategically designed plasmonic nanostructures is a promising approach for display applications with unprecedented high-resolution. However, it is disadvantageous in that the optical response is fixed once the structure is determined. Therefore, obtaining high modulation depth with reversible optical properties while maintaining its fixed nanostructure is a great challenge in nanophotonics. In this work, dynamic color tuning and switching using tungsten trioxide (WO3), a representative electrochromic material, are demonstrated with reflection-type and transmission-type optical devices. Thin WO3 films incorporated in simple stacked configurations undergo dynamic color change by the adjustment of their dielectric constant through the electrochromic principle. A large resonance wavelength shift up to 107 nm under an electrochemical bias of 3.2 V could be achieved by the reflection-type device. For the transmission-type device, on/off switchable color pixels with improved purity are demonstrated of which transmittance is modulated by up to 4.04:1.

Doublet metalens design for high numerical aperture and simultaneous correction of chromatic and monochromatic aberrations.

Metalens is one of the most prominent applications among metasurfaces since it gives possibilities to replace the conventional lenses for compactness and multi-functionalities. Recently, many studies have been demonstrated to overcome the aberrations of the metalenses for high performance practical applications. Previous studies have used the methods that control the dispersion of meta-atoms for correcting chromatic aberrations and use doublet platform for correcting monochromatic aberrations. Despite these studies and the large demands for simultaneous correction of the aberrations in high numerical aperture metalens, the simultaneous correction has not been demonstrated yet. In this paper, we report the doublet metalens design with high numerical aperture which corrects longitudinal chromatic aberration and four monochromatic aberrations including spherical aberration, coma, astigmatism, and field curvature simultaneously for the three primary visible colors. Based on the novel doublet platform, the multi-wavelength targeted correction lens and geometric phase lens with color filtering functionality are utilized. Our doublet metalens has numerical apertures of 0.33, 0.38, and 0.47 for 445 nm, 532 nm, and 660 nm, respectively. The back focal length of our doublet metalens remains nearly 360 µm for target wavelengths and incident angles up to 30 degrees.

Reconfigurable all-dielectric Fano metasurfaces for strong full-space intensity modulation of visible light.

Dynamically reconfigurable nanoscale tuning of visible light properties is one of the ultimate goals both in the academic field of nanophotonics and the optics industry demanding compact and high-resolution display devices. Among various efforts incorporating actively reconfigurable optical materials into metamaterial structures, phase-change materials have been in the spotlight owing to their optical tunability in wide spectral regions including the visible spectrum. However, reconfigurable modulation of visible light intensity has been limited with small modulation depth, reflective schemes, and a lack of profound theoretical background for universal design rules. Here, all-dielectric phase-change Fano metasurface gratings are demonstrated for strong dynamic full-space (reflection and transmission) modulation of visible intensities based on Fano resonances. By judicious periodic couplings between densely arranged meta-atoms containing VO2, phase-change induced thermo-optic modulation of full-space intensities is highly enhanced in the visible spectrum. By providing intuitive design rules, we envision that the proposed study would contribute to nanophotonics-enabled optoelectronics technologies for imaging and sensing.

Ultracompact meta-pixels for high colour depth generation using a bi-layered hybrid metasurface.

Nano-structural colour pixels have attracted much attention as promising solutions for compact display devices. However, it is difficult to miniaturize and integrate conventional transmissive colour filtering components for high resolution pixels within subwavelength scale without sacrificing colour depth. Here, we propose a novel colour pixel structure using bi-layered hybrid metasurfaces that are composed of aluminum nanograting and amorphous silicon nanorod layers. The independent high-contrast control of resonance intensity and spectral position is achieved by anisotropic Mie resonances and cavity effect between stacked two metasurfaces. Moreover, the proposed structures permit the wide colour gamut through the novel physical principles. In addition, a meta-pixel which can provide gradual tuning of colour is demonstrated to obtain high colour depth. The proposed structures are expected to be fruitful for the development of next generation display and imaging systems.

Simultaneous control of polarization and amplitude over broad bandwidth using multi-layered anisotropic metasurfaces.

In this paper, the broadband transmissive modulation of polarization and amplitude is demonstrated with high efficiency and tunability using multi-layered aluminum metasurfaces. Broadband and nondispersive optical rotation in the optical frequency region is realized by using Fabry-Pérot-like cavity and phase compensation. Simultaneously, the transmission amplitude can be independently controlled by adjusting the twist angle of the anisotropic metasurfaces. The proposed polarization-amplitude modulators are numerically demonstrated to achieve large tunability with an amplitude modulation depth of 0.95 and maximum rotation angle of 180°.

Open reduction of zygoma fractures with the extended transconjunctival approach and T-bar screw reduction.

BACKGROUND: Zygomaticomaxillary complex (ZMC) fractures mostly occur in the form of tripod fractures. The surgical field is accessed using a combination of three classic approaches. However, the subciliary incision may have unfavorable aesthetic results. Herein, the authors report the advantages of the extended transconjunctival approach (ETA) combined with T-bar screw reduction in minimizing scarring and complications for the treatment of ZMC fractures. METHODS: A total of 26 patients underwent ZMC reduction through the ETA and intraoral approach. A skin incision measuring roughly 5 to 8 mm in length was placed following the lateral canthal skin crease. After releasing the inferior crus of the lateral canthal tendon for canthotomy, the medial periosteum of the lateral orbital rim was preserved for canthal reattachment. A limited subperiosteal dissection and partial relaxing incision of the orbicularis oculi were performed to expose the fracture line of the inferior orbital rim and zygomaticofrontal suture. Reduction was performed using a T-bar screw through the transconjunctival incision and an elevator through the intraoral incision. RESULTS: The aesthetic and functional results were excellent. Successful reduction was achieved and the skin incision was less than 8 mm in 20 cases (76.9%). Only six patients had an additional skin incision (less than 5 mm) to achieve reduction. No cases of ectropion, entropion, or excessive scarring were noted. CONCLUSIONS: The ETA using a T-bar screw is a useful method for maximizing aesthetic results in ZMC fractures, with the advantages of minimal scarring, faster recovery, and maintenance of pretarsal fullness.

Plasmonic metasurface cavity for simultaneous enhancement of optical electric and magnetic fields in deep subwavelength volume.

It has been hard to achieve simultaneous plasmonic enhancement of nanoscale light-matter interactions in terms of both electric and magnetic manners with easily reproducible fabrication method and systematic theoretical design rule. In this paper, a novel concept of a flat nanofocusing device is proposed for simultaneously squeezing both electric and magnetic fields in deep-subwavelength volume (~λ3/538) in a large area. Based on the funneled unit cell structures and surface plasmon-assisted coherent interactions between them, the array of rectangular nanocavity connected to a tapered nanoantenna, plasmonic metasurface cavity, is constructed by periodic arrangement of the unit cell. The average enhancement factors of electric and magnetic field intensities reach about 60 and 22 in nanocavities, respectively. The proposed outstanding performance of the device is verified numerically and experimentally. We expect that this work would expand methodologies involving optical near-field manipulations in large areas and related potential applications including nanophotonic sensors, nonlinear responses, and quantum interactions.

Bilateral interdigitated Pacman flap for round and oval facial defects.

BACKGROUND: Skin texture and color are important considerations during the reconstruction of facial defects, and anatomical borders should be preserved. Therefore, a local flap is a better option. In these cases, the authors repaired facial defects using a bilateral interdigitated VY flap. OBJECTIVE: We aim to present a modified bilateral Pacman flap technique for the reconstruction of round and oval facial defects. MATERIALS AND METHODS: We performed a retrospective chart review of 25 patients (26 cases) who underwent bilateral interdigitated Pacman flap repair of round and oval facial defects after Mohs surgery for skin cancer from January 2012 to December 2017. The defect sizes ranged from 0.7 to 8.4 cm2 (mean 3.1 cm2). RESULTS: All defects were covered successfully and the flaps survived in all cases. One patient had partial flap necrosis that resolved spontaneously. No flap contraction, distortion, or severe scar formation was observed in any patient during the 12-month follow-up period. CONCLUSION: The bilateral interdigitated Pacman flap can cover round and oval facial defects without distortion or central dog-ear deformity. This method is a useful option for facial restoration in selected cases.

Electrically tunable multifunctional metasurface for integrating phase and amplitude modulation based on hyperbolic metamaterial substrate.

Active metasurfaces, which are tunable and reconfigurable nanophotonic structures with active materials, have been in spotlight as a versatile platform to control the profiles of scattered light. These nanoscale structures show surpassing functionalities compared to the conventional metasurfaces. They also play an important role in a wide range of applications for imaging, sensing, and data storage. Hence, the expansion of functionalities has been highly desired, in order to overcome the limited space constraints and realize the integration of several optical devices on a single compact platform. In this context, an electrically tunable metasurface that enables respective modulation of the phase and amplitude of reflected light, depending on the angle of incidence at the targeted wavelength, is proposed. This resonance-based device with hyperbolic metamaterial substrate excites different kinds of highly confined modes, according to the incident angle. Indium tin oxide is employed to offer electrically tunable optical properties in the near-infrared regime. At the wavelength of 1450 nm, the proposed device modulates the phase of reflected light with ~207 degrees of modulation depth for normal incidence, whereas it shows ~86% of relative reflectance change for oblique incidence of 60 degrees. In principle, the proposed scheme might provide a path to applications for the next-generation ultracompact integrated systems.

Broadband efficient modulation of light transmission with high contrast using reconfigurable VO2 diffraction grating.

Ultra-compact dynamically reconfigurable modulation of optical transmission has been widely studied by using subwavelength-spaced resonant metasurface structures containing reconfigurable optical materials. However, it has been difficult to achieve high transmissivity, large modulation depth, and broad bandwidth simultaneously with the conventional resonance-based metasurface schemes. Here, we propose a reconfigurable phase-transition diffractive grating, made of thick VO2 ridge waveguides, for achieving the above-mentioned three goals simultaneously in the near-infrared range. Based on the large dielectric-to-plasmonic transition characteristic of VO2 in the near-infrared range, diffraction directivity of dual-VO2 ridge waveguide is designed to be tuned by thermally driven phase transition of VO2 for transverse electrically polarized illumination. Then, the diffractive VO2 ridge waveguide grating composed of the periodically arranged dual VO2 ridge waveguides is designed with on-state efficiency around 0.3 and minimum modulation depth about 0.35 over a broad bandwidth of 550 nm (1100-1650 nm). The working principle and excellent modulation performance are thoroughly verified through numerical and experimental studies.

Critical nanofocusing of magnetic dipole moment using a closed plasmonic tip.

Squeezing magnetic dipole (MD) moment into a deep subwavelegnth apex of a tapered tip has not been achieved so far owing to a specific mode volume of a MD resonance which is dependent on an operating wavelength and back reflection of nanofocused waves. We propose a novel strategy for efficient delivery and nanofocusing of optical MD at an apex of a closed resonant plasmonic tip. Due to the ultracompact area (~λ2/900) of the nanocavity and resonances assisted by partial mirrors in a plasmonic waveguide, the enhancement factor of magnetic energy density is improved over 5 times. We expect that our scheme can help to investigate strong magnetic phenomena, including enhanced magnetic transition, artificial optical magnetism, multipole nonlinear optics, biomolecular sensing, magnetic near-field imaging, and spectroscopy.

Broadband ultrathin circular polarizer at visible and near-infrared wavelengths using a non-resonant characteristic in helically stacked nano-gratings.

Modern imaging and spectroscopy systems require to implement diverse functionalities with thin thickness and wide wavelength ranges. In order to meet this demand, polarization-resolved imaging has been widely investigated with integrated circular polarizers. However, the circular polarizers which operate at the entire visible wavelengths and have a thickness of several tens of nanometers have not been developed yet. Here, a circular polarizer, operating at the entire visible wavelength range, is demonstrated using helically stacked aluminum nano-grating layers. High extinction ratio and broad operation bandwidth are simultaneously achieved by using non-resonant anisotropic characteristics of the nano-grating. It is theoretically verified that the averaged extinction ratio becomes up to 8 over the entire visible wavelength range while having a thickness of 390 nm. Also, the feasibility of the proposed structure and circular polarization selectivity at the visible wavelength range are experimentally verified. It is expected that the proposed structure will lead to extreme miniaturization of a circular polarizer and contribute greatly to the development of mobile/wearable imaging systems such as virtual reality and augmented reality displays.

Metamaterials and Metasurfaces for Sensor Applications.

Electromagnetic metamaterials (MMs) and metasurfaces (MSs) are artificial media and surfaces with subwavelength separations of meta-atoms designed for anomalous manipulations of light properties. Owing to large scattering cross-sections of metallic/dielectric meta-atoms, it is possible to not only localize strong electromagnetic fields in deep subwavelength volume but also decompose and analyze incident light signal with ultracompact setup using MMs and MSs. Hence, by probing resonant spectral responses from extremely boosted interactions between analyte layer and optical MMs or MSs, sensing the variation of refractive index has been a popular and practical application in the field of photonics. Moreover, decomposing and analyzing incident light signal can be easily achieved with anisotropic MSs, which can scatter light to different directions according to its polarization or wavelength. In this paper, we present recent advances and potential applications of optical MMs and MSs for refractive index sensing and sensing light properties, which can be easily integrated with various electronic devices. The characteristics and performances of devices are summarized and compared qualitatively with suggestions of design guidelines.