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The FCC structured CoCrFeMnNi high entropy alloy (HEA) has attracted great attention due to its excellent ductility and strain hardening ability, but the lowest yield strength is insufficient for structural applications. To achieve high strength and ductility, we developed a new strategy called harmonic structure (HS) consisting of soft coarse and hard fine grains via controlled mechanical milling time. The SEM and EBSD microscopic characterizations reveal that the formation of HS from surface to the interior of powder is due to a difference in the degree of plastic deformation. The hardness of HS HEAs increased with increasing distance from center to surface regions due to a reduction in grain size. Compared with the homogeneous HEA, the yield strength of HS HEAs increased from 370 MPa to 730 MPa and 760 MPa due to grain boundary strengthening, dislocation strengthening, and twin boundary strengthening effects. While HS HEAs exhibited enhanced strain hardening ability due to gradient structure with their mechanical incompatibility provide back stress strengthening. Furthermore, the compressive deformation behavior of homogeneous and HS HEAs was analyzed by microstructural evolution.

Historically, nanophotonics deals with a control of light at the nanoscale being closely connected with the rapid advances in plasmonics – the physics of surface plasmon polaritons supported by metal–dielectric interfaces. Properly engineered nanostructures allow the subwavelength propagation of light and its strong confinement in nanowaveguides and nanocavities, making possible the field enhancement and lasing. Spaser was suggested as a special type of nanolaser with a very small footprint that can be modulated quickly thus becoming a good candidate for on-chip optical data processing. However, recent developments in the physics of high-index dielectric nanoparticles and resonant dielectric metasurfaces allowed to advance the field of nanophotonics and introduce novel nonplasmonic nanostructures and nanolasers empowered by topology and interference effects. Here we present first some examples of experimentally realized spasers, and then discuss the recent developments in the cutting-edge high-index dielectric nanostructures employed for nonplasmonic nanolasers based on Mie resonances, anapole states, bound states in the continuum, and the physics of topological phases.

Wavelength-scale lasers provide promising applications through low power consumption requiring for optical cavities with increased quality factors. Cavity radiative losses can be suppressed strongly in the regime of optical bound states in the continuum; however, a finite size of the resonator limits the performance of bound states in the continuum as cavity modes for active nanophotonic devices. Here, we employ the concept of a supercavity mode created by merging symmetry-protected and accidental bound states in the continuum in the momentum space, and realize an efficient laser based on a finite-size cavity with a small footprint. We trace the evolution of lasing properties before and after the merging point by varying the lattice spacing, and we reveal this laser demonstrates the significantly reduced threshold, substantially increased quality factor, and shrunken far-field images. Our results provide a route for nanolasers with reduced out-of-plane losses in finite-size active nanodevices and improved lasing characteristics., Though laser action has been reported for optical bound states in the continuum (BIC) cavities with high quality factors, these BIC lasers lacked practical applicability. Here, the authors report an ultralow-threshold super-BIC laser featuring merged symmetry-protected and accidental BICs.

Solid-state quantum emitters (QEs) are fundamental in photonic-based quantum information processing. There is strong interest to develop high-quality QEs in III-nitride semiconductors because of their sophisticated manufacturing driven by large and growing applications in optoelectronics, high voltage power transistors, and microwave amplifiers. Here, the generation and direct integration of QEs in an aluminum nitride-based photonic integrated circuit platform is reported. For individual waveguide-integrated QEs, an off-chip count rate exceeding 6 × 104 counts per second (cps; saturation rate >8.6 × 104 cps) is measured at room temperature under continuous-wave (CW) excitation. In an unpatterned thin-film sample, antibunching with g(2)(0) ∼0.08 and photon count rates exceeding 8 × 105 cps (saturation rate >1 × 106 cps) are measured at room temperature under CW excitation. Although spin and detailed optical line width measurements are left for future work, these results already show the potential for high-quality QEs monolithically integrated in a wide range of III-nitride device technologies that would enable new quantum device opportunities and industrial scalability., United States. Army Research Office MURI ((Ab-Initio Solid-State Quantum Materials Grant W911NF-18-1-0431), National Science Foundation (U.S.). Research Advanced by Interdisciplinary Science and Engineering (Grant CHE-1839155), Air Force Research Laboratory. RITA program ( FA8750-16-2-0141), National Research Foundation of Korea (Grants 2015R1A6A3A03020926 and 2018R1D1A1B07043390)

Photolithography is the prevalent microfabrication technology. It needs to meet resolution and yield demands at a cost that makes it economically viable. However, conventional far-field photolithography has reached the diffraction limit, which imposes complex optics and short-wavelength beam source to achieve high resolution at the expense of cost efficiency. Here, we present a cost-effective near-field optical printing approach that uses metal patterns embedded in a flexible elastomer photomask with mechanical robustness. This technique generates sub-diffraction patterns that are smaller than 1/10th of the wavelength of the incoming light. It can be integrated into existing hardware and standard mercury lamp, and used for a variety of surfaces, such as curved, rough and defect surfaces. This method offers a higher resolution than common light-based printing systems, while enabling parallel-writing. We anticipate that it will be widely used in academic and industrial productions., Photolithography is an established microfabrication technique but commonly uses costly shortwavelength light sources to achieve high resolution. Here the authors use metal patterns embedded in a flexible elastomer photomask with mechanical robustness for generation of subdiffraction patterns as a cost effective near-field optical printing approach.

Purpose: The most common risk factor for fecal incontinence (FI) is obstetric injury. FI affects 1.4%–18% of adults. Most patients are unaware when they are young, when symptoms appear suddenly and worsen with aging. Autologous fat graft is widely used in cosmetic surgical field and may substitute for injectable bulky agents in treating FI. Authors have done fat graft for past several years. This article reports the effectiveness of the fat graft in treating FI and discusses satisfaction with the procedure.Methods: Fat was harvested from both lateral thighs using 10-mL Luer-loc syringe. Pure fat was extracted from harvests and mixed with fat, oil, and tumescent through refinement. Fats were injected into upper border of posterior ano-rectal ring, submucosa of anal canal and intersphincteric space. Thirty-five patients with FI were treated with this method from July 2016 to February 2017 in Busan Hangun Hospital. They were 13 male (mean age, 60.8 years) and 22 female patients (mean age, 63.3 years). The Wexner score was checked before procedure. We evaluated outcome in outpatients by asking the patients. For 19 patients we checked the Wexner score after procedure.Results: Symptom improved in 29 (82.9%), and not improved in 6 (17.1%). In 2 of 6 patients, they felt better than before procedure, although not satisfied. No improvement in 4. Mean Wexner score was 9.7 before procedure. There were no serious complications such as inflammation or fat embolism.Conclusion: Autologous fat graft can be an effective alternative treatment for FI. It is safe and easy to perform, and cost effective.

Efficient integration of a single-photon emitter with an optical waveguide is essential for quantum integrated circuits. In this study, we integrated a single-photon emitter in a hexagonal boron nitride (h-BN) flake with a Ag plasmonic waveguide and measured its optical properties at room temperature. First, we performed numerical simulations to calculate the efficiency of light coupling from the emitter to the Ag plasmonic waveguide, depending on the position and polarization of the emitter. In the experiment, we placed a Ag nanowire, which acted as the plasmonic waveguide, near the defect of the h-BN, which acted as the single-photon emitter. The position and direction of the nanowire were precisely controlled using a stamping method. Our time-resolved photoluminescence measurement showed that the single-photon emission from the h-BN flake was enhanced to almost twice the intensity as a result of the coupling with the Ag nanowire. We expect these results to pave the way for the practical implementation of on-chip nanoscale quantum plasmonic integrated circuits.

Topological photonics provides a fundamental framework for robust manipulation of light, including directional transport and localization with built-in immunity to disorder. Combined with an optical gain, active topological cavities hold special promise for a design of light-emitting devices. Most studies to date have focused on lasing at topological edges of finite systems or domain walls. Recently discovered higher-order topological phases enable strong high-quality confinement of light at the corners. Here, we demonstrate lasing action of corner states in nanophotonic topological structures. We identify several multipole corner modes with distinct emission profiles via hyperspectral imaging and discern signatures of non-Hermitian radiative coupling of leaky topological states. In addition, depending on the pump position in a large-size cavity, we generate selectively lasing from either edge or corner states within the topological bandgap. Our studies provide the direct observation of multipolar lasing and engineered collective resonances in active topological nanostructures., Higher-order photonic topological states, such as corner states, could enable robust and high-quality confinement of light to a small mode volume. Here, the authors demonstrate lasing from topological multipole corner states and investigate their emission profiles via hyperspectral imaging.

Electronic pacemakers can treat electrical conduction disorders in hearts; however, they are invasive, bulky, and linked to increased incidence of infection at the tissue-device interface. Thus, researchers have looked to other more biocompatible methods for cardiac pacing or resynchronization, such as femtosecond infrared light pulsing, optogenetics, and polymer-based cardiac patches integrated with metal electrodes. Here we develop a biocompatible nongenetic approach for the optical modulation of cardiac cells and tissues. We demonstrate that a polymer-silicon nanowire composite mesh can be used to convert fast moving, low-radiance optical inputs into stimulatory signals in target cardiac cells. Our method allows for the stimulation of the cultured cardiomyocytes or ex vivo heart to beat at a higher target frequency.

Apparatus for fluorescence-based single photon generation includes collection optics and various setups for characterization. Managing this system often reveals complexity in such a way that adjusting in a small region changes optimal alignments of others. We suggest here a modular system, where the optimal alignment is given to each compartment and tested independently. Based on this concept, we built a system for single photon generation with fluorescence center in hexagonal boron nitride nano-flake, advantageous for scaling up the number of single mode fiber output and a high degree of stability. The system allowed for a practical use of single photon stream extended over an hour with a uniform count rate of small fluctuation levels., Comment: 5 pages, 5 figures

In this work, we present a detailed photophysical analysis of recently-discovered optically stable, single photon emitters (SPEs) in Gallium Nitride (GaN). Temperature-resolved photoluminescence measurements reveal that the emission lines at 4 K are three orders of magnitude broader than the transform-limited widths expected from excited state lifetime measurements. The broadening is ascribed to ultra-fast spectral diffusion. Continuing the photophysics study on several emitters at room temperature (RT), a maximum average brightness of ~427 kCounts/s is measured. Furthermore, by determining the decay rates of emitters undergoing three-level optical transitions, radiative and non-radiative lifetimes are calculated at RT. Finally, polarization measurements from 14 emitters are used to determine visibility as well as dipole orientation of defect systems within the GaN crystal. Our results underpin some of the fundamental properties of SPE in GaN both at cryogenic and RT, and define the benchmark for future work in GaN-based single-photon technologies.

© 2017 IEEE. Non-classical light sources, such as atoms and atom-like emitters play central roles in many areas of quantum information processing with applications as single photon generators, sources for nonlinearity and quantum memories. Solid-state quantum emitters have attracted growing interest due to the promise of combining remarkable optical properties with the convenience of scalability [1]. In recent years, there has been tremendous progress in developing quantum emitter systems based on crystallographic defects in wide-bandgap semiconductors. Nitrogen vacancies (NV) in diamond were among the first studied systems due to the well-defined optical transitions as well as electronic spin states that can be controlled optically. Quantum spins in diamond are among the most advanced systems in solid state for quantum based technologies such as quantum computing or quantum sensing [2]. Nevertheless, solid-state quantum emitters are not only limited to diamond and efforts to engineer single photon emitters (SPE) based on atom-like defects in scalable system have expanded beyond NV centers in diamond. Similar quantum emitters have been discovered in many other wide-bandgap host materials, including silicon carbide (SiC), III-nitride semiconductors such as gallium nitride (GaN) and aluminum nitride (AlN), and layered materials such as hexagonal boron nitride (hBN) [1]. Here, we will review our recent progress in developing and characterizing new quantum emitters in wide-bandgap semiconductors, and consider their applications as quantum light sources and sensors.

A follower can be divided into supporter, non-supporter, or neutral according to a follower’s intention to a target user. Even though a follower is identified as a supporter, an opinion may not be positive to the target user. In this paper, we propose a method to classify a follower as supporter, non-supporter or neutral. To expand information of a follower, influential transmitters who support a target user are detected by using a modified HITS algorithm. To detect a follower’s specific opinion, social issues are extracted based on tweets of influential transmitters. The thread tweets are clustered based on Latent Dirichlet Allocation for social issues. Then, sentiment analysis is conducted for the clusters of a follower. To see the effectiveness of our method, a Korean tweet collection is constructed. As a result, we found that lots of supporting followers show opposite opinions depending on particular issues.

Dielectric nano-antennas are promising elements in nanophotonics due to their low material loss and strong leaky-mode optical resonances. In particular, light scattering can be easily manipulated using dielectric nano-antennas. To take full advantage of dielectric nano-antennas and explore their new optical applications, it is necessary to fabricate three-dimensional nano-structures under arbitrary conditions such as in non-planar substrates. Here, we demonstrate full-visible-range resonant light scattering from a single dielectric optical nano-rod antenna. The nano-rod antenna was formed by electron beam-induced deposition (EBID), a promising three-dimensional nanofabrication technique with a high spatial resolution. The nano-rods consist of amorphous alloys of C and O, with a width of 180 nm on average and a length of 4.5 μm. Polarization-resolved dark-field scattering measurements show that both transverse-electric and transverse-magnetic mode resonances cover the full visible range as the height of the nano-rod antenna varies from 90 to 280 nm. Numerical simulations successfully reproduce the measured scattering features and characterize the modal properties, using the critical points dispersive dielectric constant of the EBID carbonaceous material. Our deep understanding of resonant light scattering in the EBID dielectric nano-antenna will be useful for near-field measurement or for the implementation of three-dimensional nanophotonic devices.

We present a full three-dimensional (3D) power flow analysis of an emitter-nanoantenna system. A conventional analysis, based on the total Poynting vector, calculates only the coupling strength in terms of the Purcell enhancement. For a better understanding of the emitter-nanoantenna system, not only the Purcell enhancement but also complete information on the energy transfer channels is necessary. The separation of the pure scattering and emitter output Poynting vectors enables the quantification of the individual energy transfer channels. Employing the finite-difference time-domain method (FDTD), we examine a nanodisk antenna that supports the bright dipole and dark quadrupole resonance modes for which the power flow characteristics are completely distinct, and we analyze the power flow enhancements to the energy transfer channels with respect to the wavelength, polarization, and position of the emitter coupled to the antenna. The 3D power flow analysis reveals how the constructive or destructive interference between the emitter and the antenna resonance mode affects the power flow enhancements and the far-field radiation pattern. Our proposed power flow analysis should play a critical role in characterizing the emitter-antenna system and customizing its energy transfer properties for desired applications. (C) 2015 Optical Society of America

The realization of lasers as small as possible has been one of the long-standing goals of the laser physics and quantum optics communities. Among multitudes of recent small cavities, the one-dimensional nanobeam cavity has been actively investigated as one of the most attractive candidates for effective photon confinement thanks to its simple geometry. However, the current injection into the ultra-small nano-resonator without critically degrading the quality factor remains still unanswered. Here we report an electrically driven, one-dimensional, photonic-well, single-mode, room-temperature nanobeam laser whose footprint approaches the smallest possible value. The small physical volume of ~4.6 × 0.61 × 0.28 μm3 (~8.2(λ n−1)3) was realized through the introduction of a Gaussian-like photonic well made of only 11 air holes. In addition, a low threshold current of ~5 μA was observed from a three-cell nanobeam cavity at room temperature. The simple one-dimensional waveguide nature of the nanobeam enables straightforward integration with other photonic applications such as photonic integrated circuits and quantum information devices., Lasers for on-chip optical technologies should be as small as possible. Here, Jeong et al. achieve room-temperature lasing in an electrically driven nanobeam photonic structure using only 11 holes to confine the light.

We present a systematic, theoretical investigation of the polar magneto-optical (MO) Kerr effects of a single Ni nanorod in the Mie regime. The MO Kerr rotation, ellipticity, amplitude ratio, and phase shift are calculated as a function of the length and width of the nanorod. The electric field amplitude ratio of the MO Kerr effect is locally maximized when the nanorod supports a plasmonic resonance in the polarization state orthogonal to the incident light. The plasmonic resonances directly induced by the incident light do not enhance the amplitude ratio. In the Mie regime, multiple local maxima of the MO Kerr activity are supported by the resonant modes with different modal characteristics. From the viewpoint of first-order perturbation analysis, the spatial overlap between the incident-light-induced electric field and the Green function determines the local maxima.

We propose a gold modified bow-tie plasmonic nano-antenna, which can be suitably used in combination with total internal reflection fluorescence microscopy. The plasmonic nano-antenna, supporting well-separated multiple resonances, not only concentrates the total internal reflection evanescent field at the deep subwavelength scale, but also enhances fluorescence emission by the Purcell effect. Finite-difference time-domain computations show that the enhancement of the excitation light strongly correlates with the far-field radiation pattern radiated from the antenna. Depending on the antenna geometry, the resonant modes are widely tuned and their wavelengths can be easily matched to the diverse emission or excitation wavelengths of fluorophores. (C) 2013 Optical Society of America

We demonstrate one-dimensional nanobeam photonic bandedge lasers with InGaAsP quantum wells at room temperature from the lowest dielectric band of photonic crystal nanobeam waveguides. The incident optical power at threshold is 0.6 mW (effectively ~18 μW). To confirm the lasing from the dielectric bandedge, the polarization and the photoluminescent spectra are taken from nanobeams of varying lattice constants. The observed shift of the lasing wavelength agrees well with the computational prediction.

Purpose: As the number of patients with inflammatory bowel disease (IBD) has steadily increased in Korea, IBD-associated cancers are expected to increase in number. This study investigated the clinical features of intestinal cancer in patients with IBD. 15 cancer patients had no history of treatment for IBD of more than 3 mo before diagnosis of the cancer. Eleven cancers were located in the rectum (7 in UC, 4 in CD), including 1 case of synchronous cancer. One case of small bowel cancer was found in a patient with small bowel CD. Four cases involved a mucinous adenocarcinoma. Eight of the 12 cases of an adenocarcinoma of the colon and rectum were advanced stage. Conclusion: IBD-associated intestinal cancers were found at a relatively young age, were diagnosed at an advanced stage, and had a higher proportion of mucinous adenocarcinomas than in sporadic cancer. Considering the increasing incidence of IBD and the expected increase in the number of IBD-associated cancer in Korea, every effort should be made to prevent intestinal cancer in patients with IBD and to detect it early.

Purpose: We aimed to compare the prognosis and the recurrence patterns of sporadic primary colon cancers according to the location of the cancer. Methods: One thousand four-hundred eighty-three (1,483) stage II, III colon cancer patients who had undergone a consecutive curative resection between January 1989 and December 2003 were analyzed. Hereditary, synchronous, metachronous, and recurrent colon cancers were excluded. The right colon was defined as being from the cecum to the transverse colon, and the left colon was defined as being from the splenic flexure colon to the rectosigmoid colon. The median follow-up time was 63 (3-228) mo. Results: Poorly differentiated and mucinous cell type tumors were more frequent in the right colon. T3 tumors were more frequent in the right colon. Lymph-node-positive tumors were more frequent in the left colon. The recurrence rate was higher in the left colon, but the patterns of recurrence were not different according to the tumor's location. By univariate analysis, age, preoperative serum CEA level, T-stage, N-stage, lymphovascular invasion, postoperative chemotherapy, and tumor location were significant prognostic factors associated with recurrence. By multivariate analysis, sex, preoperative serum CEA level, T-stage, N-stage, postoperative chemotherapy, and tumor location were significant prognostic factors associated with recurrence. The 5-yr disease-free survival rates were 84.0% for right colon cancer and 77.1% for left colon cancer (P= 0.005). The recurrence rates for cancers in the sigmoid colon and the rectosigmoid colon were higher than those for cancers in the cecum and the ascending colon. Conclusion: The tumor's location was an independent prognostic factor for recurrence, but the pattern of recurrence did not vary with the tumor's location.

A wavelength-scale cavity is generated by printing a carbonaceous nano-block on a photonic-crystal waveguide. The nanometer-size carbonaceous block is grown at a pre-determined region by the electron-beam-induced deposition method. The wavelength-scale photonic-crystal cavity operates as a single mode laser, near 1550 nm with threshold of approximately 100 microW at room temperature. Finite-difference time-domain computations show that a high-quality-factor cavity mode is defined around the nano-block with resonant wavelength slightly longer than the dispersion-edge of the photonic-crystal waveguide. Measured near-field images exhibit photon distribution well-localized in the proximity of the printed nano-block. Linearly-polarized emission along the vertical direction is also observed.