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This paper reports the fabrication of parallel integrated sapphire fiber Bragg gratings (SFBGs) probe sensor by the femtosecond laser point by point (PbP) method. The SFBGs probe sensor transmits optical signals through quartz multimode fiber, and takes an 8.5 mm sapphire fiber as the sensing probe, which can work stably for a long time at 1200 °C. This method can not only quickly prepare and obtain SFBGs with small bandwidth, but also obtain gratings with high reflectivity, which is about 15%. The mode field distribution in sapphire fibers with different lengths is studied by the beam quality analyzer. High-order modes are easily excited as the length of sapphire fibers increases. In addition, a spherical lens is prepared at the end of sapphire fiber, which effectively improve the signal-to-noise ratio (SNR) to 22 dB. The good spectral quality can still be maintained after holding at 1200 °C for 24 hours, and the temperature sensitivity can reach 30.19 pm/°C in the high temperature range, which is more than 2 times higher than that of quartz FBGs sensors. This parallel integrated SFBGs probe sensor overcomes the problems of doped quartz fiber element diffusion at high temperature and the instability of microstructure caused by material softening, and can be developed for long-term stable operation at 1200 °C high temperature and harsh environments. [ABSTRACT FROM AUTHOR]

As the main component of silicon (Si)-based Optic Electronics Integrated Circuit (OEIC) chip, Si-based infrared photodetector operating at communication wavebands is very important. In this paper, we report a kind of chromium (Cr)-hyperdoped black Si material fabricated using femtosecond laser pulses irradiation. The concentration of the Cr atoms in the black Si layer exceeds 1020 cm−3 and the Cr-hyperdoped Si has a large sub-bandgap absorptance (~60% for $1.31 \boldsymbol {\mu }\text{m}$). The deep-energy level introduced by Cr impurity is 0.39 eV below the bottom of conduction band and thus the ionized electron concentration is very low (~1015 cm−3). Owing to the excellent sub-bandgap absorption of Cr-hyperdoped Si, face-to-face black Si photodiodes are fabricated. Under illumination of $1.31 \boldsymbol {\mu }\text{m}$ light, the responsivity of the photodiodes based on N+-N junction reaches 0.57 A/W at 4.3 V bias. In addition, the rise and delay time of the device to the infrared light are on the order of milliseconds. [ABSTRACT FROM AUTHOR]

Blazed gratings are widely used in optical detection devices with the unique property of concentration of light energy to a desired diffraction order. However, traditional substrates for fabricating blazed gratings are easily damaged with the wear and tear in long-term usage under harsh conditions. Here, we propose the fabrication of blazed gratings on sapphire with high mechanical stability by femtosecond laser lithography combined with subsequent reactive ion etching (RIE). Various sapphire blazed gratings with periods from 2 μm to 10 μm and heights from 260 nm to 2 μm were realized to concentrate light energy (wavelengths of 405 nm, 532 nm and 633 nm) to different diffraction orders (1st, 2nd, and 3rd). The results provide great insights for the construction of micro-optical devices that have potential applications under harsh conditions. [ABSTRACT FROM AUTHOR]

Femtosecond laser additive manufacturing based on two-photon polymerization performs a useful technique for fabricating high-precision 3D structures. However, poor mechanical strength and low processing efficiency brought by near polymerization threshold processing to achieve high accuracy are still urgent problems. In this work, a definition-reinforcement-solidification (DRS) processing strategy is proposed to solve the current problems, in which DRS processing includes three steps: utilize a near-threshold femtosecond laser to accurately define the surface profile of 3D structures, perform enhanced scanning on the above structure's inner surface with a high-power femtosecond laser to increase the mechanical strength, and rapidly solidify the inner unpolymerized resin through one exposure of ultraviolet light to improve the processing efficiency. Compared with conventional near-threshold point-by-point direct writing, microstructures fabricated by the DRS strategy for a given geometry and polymer have hardness and Young's modulus values increase to 154% and 199%, respectively, and exhibit a 10000% improvement in machining efficiency without the loss of processing accuracy. Arbitrary complex 3D microstructures can be implemented rapidly via this strategy. This work will inject new vitality into two-photon polymerization additive manufacturing. [ABSTRACT FROM AUTHOR]

In recent years, femtosecond laser direct writing technology has made great progress in integrated quantum photonic circuits due to its advantages of applicability to an extensive range of materials and true 3-D ability. However, a waveguide prepared via a femtosecond laser shows a non-circular cross section and high birefringence, which seriously restricts the development of polarization encoded quantum photonic integrated chips towards greater integration and higher functions. Here, we propose an amplitude-phase double shaping method to reduce waveguide birefringence, which involves using a cylindrical lens and slits. A waveguide prepared using this method shows a circularity cross-section that reaches up to 97.6% and a birefringence that is as low as 1.49 × 10−6. Based on such an ultralow birefringence waveguide, a polarization independent Hong-Ou-Mandel quantum interferometer was fabricated. Interference visibilities for identical photon pairs in different polarization states were found to be more than 95% with a standard deviation of 0.6%. The ultra-low birefringence single-mode waveguide and the polarization-independent interferometer realized using this approach will play an important role in large-scale polarization encoding integrated quantum photonic chips. [ABSTRACT FROM AUTHOR]

Microlens array has been demonstrated to be an effective method for laser beam homogenization. However, the homogenization of high-fluence laser beam is still a great challenge due to the serious damage to the microlens-array-based homogenizer. Here, an ultra-smooth sapphire concave microlens-array-based homogenizer, which is fabricated by dry-etching-assisted femtosecond laser machining, is proposed for shaping high-fluence pulsed laser beam to a flat-top profile intensity distribution. By taking advantages of high transmittance (>70%) and low surface roughness (1.1 nm), high-fluence (5 J/cm2) and wide-band (266 nm, 532 nm and 808 nm) laser beams homogenization is successfully realized by the sapphire concave microlens arrays. [ABSTRACT FROM AUTHOR]

A novel directional torsion sensor based on a helical taper is proposed and experimentally demonstrated. The helical taper was fabricated in panda polarization-maintaining fiber by electric-arc discharge of a fusion splicer and by rotating one end fiber clamp simultaneously. The optimal parameters of the taper are the waist diameter of $60.84~\mu \text{m}$ and the length of $700~\mu \text{m}$. This torsion sensor has a sensitivity of −3.191 nm/(rad/m) in the twist rate ranges from 0 to 13.57 rad/m, which is relatively higher than the value so far reported. Then, the torsion sensor also has the ability to identify rotational direction. In addition, the helical taper is almost insensitive to temperature. [ABSTRACT FROM AUTHOR]

Here, we report embedded spiral zone plates (SZPs) processed by tightly focused femtosecond pulses, inducing a refractive index change in a sapphire crystal. The change in the index is investigated both experimentally and theoretically and found to be 0.93% lower than that before the laser irradiation. Benefiting from the investigation of the photorefraction, a high diffractive efficiency of up to 78% is achieved for the SZPs. In addition, the SZPs are embedded under the surface of the sapphire, which ensures that the components possess stable optical properties in the case of external refractive index changes. The high-performance elements having a high diffractive efficiency and stable optical performance will have tremendous applications in optical communication and optical manipulation. [ABSTRACT FROM AUTHOR]

A crystalline silicon (Si) surface was modified using nanosecond laser pulses in an argon atmosphere. The laser-modified Si (M-Si) samples have a higher performance and thermostable absorption in the broadband range (400–2400 nm) than conventional Si. The concentration of carrier electrons in the M-Si layer is at least five orders of magnitude greater than the carrier concentration of the Si substrate. Using the N+–N− junction formed between the M-Si layer and the Si substrate, visible and near-infrared (VIS-NIR) M-Si photodetectors are made. The N+–N− photodiode has good rectification characteristics and a high photoresponse to the subbandgap NIR light at 1310 nm. At the same time, the M-Si photodetector at a low reverse bias shows a large gain to the VIS-NIR light above the bandgap. By comparing the response time of the M-Si photodetector to the light of 900 and 1310 nm, the response speed of the device to the photon above-bandgap energy is faster. [ABSTRACT FROM AUTHOR]

Reconfigurably adaptive devices through the shape change offer reasonably appropriate and recoverable departures in shape, in order to satisfy changing environmental constraints or operational demands. Here, we demonstrated the humidity-responsive directional-deformation actuators based on interpenetrating composite polymer hydrogel, which were applied as moisture-controlled automatic curtain and power-OFF safety switch. In the double-layer actuators, a rigid stripe of interpenetrating polymer hydrogel by photolithography were aligned into humidity-responsive hydrogel. Through adjusting the angle of interpenetrating polymer stripe, the strip actuators deformed in various deformation orientations, including horizontal, perpendicular, left-handed helix, and right-handed helix deformation with different angles. The directional-deformation actuators were suitable as environmentally adaptive devices in the automatically roll-up and fall-down “curtain” application corresponding to humidity change, and automatically power-OFF safety switch when ambient humidity suddenly increased. These examples of model application exhibited potential significance of the actuators as soft robots. [ABSTRACT FROM AUTHOR]

We report an ultrathin Au transparent electrode with the thickness of only 4.4 nm based on an S-1805/Ag hybrid nucleation layer and its application in flexible organic light-emitting devices (OLEDs) as the replacement of indium tin oxide (ITO) anode. The Volmer–Weber growth mode of the deposited Au film has been suppressed successfully by using the hybrid nucleation layer, in which the S-1805 acts as a substrate modification layer and 0.6 nm Ag acts as a seeding layer. The resulting ultrathin Au film with the thickness of 4.4 nm shows high transparency, high conductivity, and ultrasmooth surface. A 25% improvement in efficiency has been demonstrated for the OLEDs with ultrathin Au anodes compared to the ITO-based devices. The application of the high-performance ultrathin Au electrodes in OLEDs results in high flexibility and mechanical robustness with small performance variations after 2100 bending cycles with a 7.5 mm bending radius. [ABSTRACT FROM AUTHOR]

Aiming for structural health monitoring applications in harsh environments, a high-order sapphire fiber Bragg grating (HO-SFBG) written with a femtosecond (fs) laser in a large-diameter sapphire fiber is demonstrated. The radial refractive index modulation area induced by scanning exposure is greater than 60% of the fiber cross-section area. The large mode overlapping area leads to a transmission resonance strength of approximately 3.0 dB. As demonstrated by numerical simulations of mode excitation and multimode resonance, each mode resonance is significantly superposed when the coupling coefficient is above 0.0005. A study of the high-temperature and strain sensing characteristics of the HO-SFBG shows that each high-order resonance has different response characteristics. This type of large-diameter SFBG has important application potential for high-temperature smart materials with embedded fiber sensors. [ABSTRACT FROM AUTHOR]

Micro-ripple and micro-bead structures are formed on a silicon (Si) surface after irradiation with femtosecond laser pulses in nitrogen (N2) atmosphere. Simultaneously, supersaturated nitrogen (N) atoms, with a concentration above 1020 cm−3, are doped into the textured black Si layer via laser ablation. The N-doped Si exhibits strong below-bandgap infrared absorption from 1.1 to 2.5~\mu \textm , which remains nearly unchanged after annealing for 30 min at 873 K. The mechanism of this thermally stable infrared absorption is analyzed by first-principles calculations. According to the transmission electron microscopy results, multiple phases (including single crystalline, nanocrystalline, and amorphous phases) are observed in the laser-irradiated layer. Hall Effect measurements prove that N-dopants induce a low background free-carrier concentration ( \sim 1.67\times 10^16\,\,\text cm^-3 ). Finally, a Schottky-based bulk structure photodiode is made. This broadband photodiode exhibits good thermal stability and a photo-responsivity of 5.3 mA/W for 1.31~\mu \textm at a reverse bias of 10 V. [ABSTRACT FROM PUBLISHER]

A small-period long-period grating (LPG) with a period of 40\mu \textm fabricated in a single-mode fiber by femtosecond laser direct writing has been demonstrated. A series of high-order Bragg resonant peaks of Bragg grating and attenuation bands of LPG can be observed simultaneously in the broadband spectrum range that exhibited different responses to surrounding refractive index, temperature, and axial strain. Meanwhile, we provided a sensitivity matrix to correct the errors caused by temperature in measurements of refractive index and strain to achieve a dual-parameter fiber sensor at high temperature. [ABSTRACT FROM PUBLISHER]

Ge–Sb–Te superlattice (GST-SL) is a newly emerging electronic material for nonvolatile phase-change memory with ultralow energy cost. However, its switching mechanism is still unclear with intensive debates. In this work, by first-principles calculations and an electron counting model study, we study the possible mechanism of phase change and the accompanying property transition of GST-SL. GST-SL are separated into individual layers by van der Waals gaps. We demonstrate that both the global chemical stoichiometry of the material and the local chemical stoichiometry of individual layer block are required to have an insulating band gap according to an electron counting model analysis. The electrical property can be adjusted by changing the local stoichiometry, such as producing defects around van der Waals gaps. Inspired by a previous experiment, we propose that a stacking-fault motion can spontaneously alter the band gap and results in a metal–insulator transition. This transition may provide a significant change of carrier concentration and indicate an ultralow energy-consumption process with a low energy barrier. The present investigations reveal a picture of electrical transition in GST-SL and may guide us to improve its device performances. [ABSTRACT FROM PUBLISHER]

Optical microcavities have been paid enormous attentions as a basic integrated element in photonic devices including micromodulators, microfilters, and microsensors. In particular, the microcavities that can produce unidirectional and single-mode lasing emissions are greatly demanded to meet the challenge of integrating high-efficiency and high-sensitivity optical functional systems. Herein, a three-dimensional polymer microlaser composed of stacked circular-ring-shaped and spiral-ring-shaped microcavities is fabricated directly on a narrow bandpass filter substrate by the femtosecond laser processing technique. The on-chip polymer microlaser provides a room-temperature, low-threshold, unidirectional, and single-mode laser output, resulting from the coupling between the two stacked microcavities. The fabrication of the on-chip low-threshold polymer microlaser opens up a possibility toward the integration of a variety of polymer microcavities for organic optoelectronic devices. [ABSTRACT FROM PUBLISHER]

Gold (Au)-doped-textured silicon (Si) material with a thermostable absorption below bandgap (>50%) is obtained by femtosecond laser irradiation. Although the concentration of Au impurity (1019 cm−3 ) in textured Si is at least four orders of magnitude greater than the solid solubility of Au in crystalline Si, the sheet carrier density (approximately 1010 cm−2) in Au-doped Si is very low due to a self-compensation effect of Au impurity in Si material. The infrared absorption of Au-doped Si is related to laser-induced-structural defects and sub-band absorption of deep energy levels of Au in Si, which is determined by temperature-dependent Hall Effect measurement. Besides supersaturated doping of Au, a gold silicide phase is formed at textured Si surface. [ABSTRACT FROM PUBLISHER]

Femtosecond (fs) laser annealing has been applied to improve the crystalline quality and absorptance below bandgap of ion implanted silicon (Si) with sulfur (S). The doping concentration of S is up to 10^20 atoms/cm3, which is at least four orders of magnitude higher than the solid solubility of S in crystalline Si. According to the Raman spectra, after fs laser irradiation with appropriate laser energy, the crystal quality is evidently better than primary ion implanted sample. Moreover, the optical absorption coefficient at wavelengths of 1100~2400 nm is up to 1.54 \times 10^4 cm ^\mathrm -1 , which is much larger than the contribution of free carriers. Excessive laser energy will induce serious ablation effect and cause the removing of doping layer. We consider that the high absorption is a combination of sub-bandgap transition of S-related localized states, free carrier absorption, ion implantation induced defect absorption and fs laser irradiation induced defect absorption. In the end, a photo-response of 8.4 mA/W is obtained for the photodiode for 1310 nm detection light. [ABSTRACT FROM PUBLISHER]

In this paper, we have demonstrated an efficient perovskite light-emitting device (PeLED) by improving perovskite crystallization. The improved perovskite crystallization has been achieved by pretreating the underneath poly (3, 4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) layer with N, N-dimethylformamide (DMF) solvent before single-step spin-coating the perovskite, which results in a prolonged wet environment during the perovskite thermal annealing process to promote the grain growth. The improved perovskite crystallization induces a perovskite thin film with higher surface coverage, fewer defects, and larger grain size with less scattering of grain boundaries. As a result, the PeLEDs exhibit maximum external quantum efficiency of 0.728% and maximum luminance of 2088 cd/m2, which represent a significant improvement over the control devices. Moreover, perovskite films with improved crystalline quality have proved its beneficial effect on the device stability. [ABSTRACT FROM PUBLISHER]

We report a novel hybrid refractive–diffractive microlens combined with spiral phase for the generation of optical vortex, which is fabricated via femtosecond laser direct writing technology. The unique optical performance of focusing capability is demonstrated. At the focus position, the hollow focus with different integer topological charges is investigated. Moreover, experimental results are supported by finite-element calculation. The novel microlens generating an optical vortex will fulfill important applications in optical manipulation, multistate information encoding, quantum communication, and computation, particularly in the compaction, integration, and simplification of optical vortex generation system. [ABSTRACT FROM PUBLISHER]

Suspended structures have attracted a great deal of attention in the field of micro-technology and nanotechnology for their important functions. However, the fabrication of the suspended structures is typically cumbersome and time-consuming and requires complicated processes, such as multiple deposition, photolithography, and etching. Here, we report a new method of fabricating flexible suspended structures by femtosecond laser direct writing followed by wet chemical alkaline (KOH) etching. Our proposed method will enable convenient and flexible fabrication of suspended structures for a wide variety of applications in the field of micro-technology and nanotechnology. [ABSTRACT FROM PUBLISHER]

Here, we report a sapphire-based Fresnel zone plate (FZP), which is fabricated by femtosecond laser direct writing assisted with subsequent wet etching. With this method, we solved the problem of high surface roughness caused by ultrafast femtosecond laser processing. We have obtained $\sim 12$ -nm average surface roughness smaller than 1/25 of the optical working wavelength. As-formed sapphire FZP also exhibited a well-defined geometry. More importantly, ultraviolet (UV) light focusing and imaging can be easily achieved. Due to the high material hardness, thermal and chemical stabilities of sapphire, such sapphire FZP, may have great potential in UV imaging and focusing under some harsh environments. [ABSTRACT FROM PUBLISHER]

A metal-coated hemisphere microcavity is realized by a simple self-assembled process. Plasmon-photon hybrid modes are produced by the metallic microcavity, and the lasing wavelength exhibits a blue shift when compared with no-metal cavities. Simulation shows that the blue shift originates from the redistribution of the electric-field intensity in the microcavity. The metal-coated microcavity exhibits excellent lasing performance at room temperature with a quality factor of $\sim 2500$ , owing to high-smooth surface of the hemisphere. Our findings may provide a promising candidate for fundamental investigation of plasmon and photon modes interaction and cavity electrodynamics. [ABSTRACT FROM PUBLISHER]

We report in this letter a concave–convex microlens (CCML) consisting of two different high curvature surfaces. Compared with the conventional plano-convex microlenses, the CCML not only allows for more design freedom, but also offers significantly improved optical performance, particularly minimization of aberration, as is critical when the size of optical components is small. Experimentally, focusing capability at different wavelengths was demonstrated, and the axial chromatic aberration was found significantly reduced to $\sim 4.6$ % of the focal length shift under wavelength 450–660 nm. [ABSTRACT FROM PUBLISHER]

We investigated the strain and surface structural properties of a strain-relaxed Si1–xGex alloy layer with high Ge-content using optical surface second-harmonic generation. Here, the Si1–xGex alloys are heteroepitaxial, and they are deposited onto Si substrates via ultra-high-vacuum-chemical vapor deposition. The in-plane strain and the composition $x$ of the Si1–xGex alloys were determined using Raman spectroscopy. The SH signals generated from three Si1–xGex alloy surfaces versus the rotational angle of the substrate were measured. The SH intensities for the combination of s-input/p-output polarization show fourfold symmetry; however, for s-input/s-output, the SH signals show eightfold symmetry with the rotational angle. Residual strain would induce an enhancement of the isotropic p-output SH component in the Fourier transform coefficient. Finally, the degree of symmetry of the SH signals from these three Si1–xGex alloy surfaces versus the rotational angle was related with the surface pit defects (densities and sizes) and surface roughness. [ABSTRACT FROM AUTHOR]

We proposed an optical magnetic field sensor with the temperature correction capability, which is based on an optical microfiber taper (OMT) integrated with magnetic fluid. The OMT is fabricated simply by fused tapering and then sealed into a capillary tube filled with magnetic fluid. The sensor is highly sensitive to magnetic field with the sensitivity of 0.171 nm/Oe in the range of 20–70 Oe at room temperature 25 °C. Moreover, there is a linear relationship between the wavelength shift and temperature in the range of 30 °C–80 °C, and a sensitivity of −0.587 nm/°C has been achieved. Based on these experiments, we provided a sensitivity matrix to correct the errors caused by temperature in order to measure magnetic field more accurately. [ABSTRACT FROM PUBLISHER]

Micronanostructured silicon surface is irradiated by femtosecond laser pulses at sulfur hexafluoride atmosphere (S-doped black silicon) and photodiodes are successfully fabricated based on this material. From the scanning electronic microscope and atomic force microscope images, the black silicon layer shows micro-nanocomplex structures (microcones covered with nanoparticles). The optoelectrical properties of n+-p junction are formed between S-doped micro-nanostructured silicon-layer and substrate after thermal annealing. For the n+-p photodiode, current–voltage characteristics at different incident light powers have been investigated. The responsivity for 800-nm wavelength is 0.69 A/W at −5 V reverse bias, which is close to that of the usual commercial Si p-i-n photodiode. The present devices are stable and well reproducible. [ABSTRACT FROM PUBLISHER]

Chalcogen-doped microstructural silicon irradiated by femtosecond laser has high near-uniform absorption on a broad spectrum, but the factors leading to infrared absorption are complex and remain an open problem. To clarify the origin of infrared absorption besides hyperdoped Chalcogen atoms, microstructural silicon is fabricated by femtosecond laser under vacuum condition. The relationship between infrared absorption and as-formed new phases (amorphous silicon: $\alpha $ -Si and nanocrystal silicon) is established. It indicates that the infrared absorption is caused by defects related to Urbach states from \alpha $ -Si or nanocrystal Si, and these metastable defects disappeared after a thermal annealing process. From the absorption spectrum of microstructural silicon after etching at different times, it could be figured out that the Urbach states exist in both the surface and subsurface regions of black silicon at a depth of about 2.4 \mu \text{m} . [ABSTRACT FROM PUBLISHER]

A compact fiber Mach–Zehnder interferometer based on tapered hollow optical fiber (THOF) has been demonstrated. The THOF is sandwiched between two single mode fibers (SMFs), forming a SMF-THOF-SMF (STS) structure. The discharging during the splicing and tapering processes induces the collapsed regions in the hollow fiber, which form the modal coupling/re-coupling areas of the interferometer. The THOF has a length of about 2 mm and the taper waist diameter is about 66.5 \mu \textm . The refractive index (RI), stress, and temperature response properties of the STS interferometer have been investigated, which show a high RI sensitivity and low temperature cross-sensitivity. The STS interferometer holds the merits of compact structure, low cost and easy fabrication, making it a suitable candidate in the biochemical and physical sensing fields. [ABSTRACT FROM PUBLISHER]

We report in this letter the fabrication of edge-alignment-coupled whispering gallery mode photonic-molecule microdisk by femtosecond laser direct writing of dye-doped resins, which results in single-mode lasing output. Under picosecond laser pumping, the excited energy is distributed at the disk periphery and the coupling happens at the overlapping edge of two disks. As a result of mode coupling through Vernier effect, single-mode lasing is achieved in two-microdisk and three-microdisk coupled lasers of various sizes. The effect in the coupled system is confirmed by numerical simulation. This letter may open up a new avenue to the 3-D integrated optoelectronics. [ABSTRACT FROM PUBLISHER]

A novel highly sensitive fiber sensor for transverse load and temperature measurement has been fabricated by polydimethylsiloxane (PDMS) packaging an S fiber taper (SFT). The PDMS coating is an effective transverse load and temperature transducer due to its material characteristics, such as low Young’s modulus, high Poisson’s ratio, and large thermooptic coefficient, which can efficiently transfer the lateral force into axial tension on the SFT or convert temperature into refractive index (RI) change around SFT. Because the SFT is highly sensitive to axial strain and surrounding RI, the PDMS-coated SFT will have high sensitivities of transverse load and temperature, which have been experimentally obtained up to −29.03 nm/N and −2.17 nm/°C, respectively. In addition, to solve the problem of cross sensitivity, two-wavelength demodulation method has been proposed for simultaneous measurement of transverse load and temperature. [ABSTRACT FROM PUBLISHER]

We experimentally demonstrate fabrication of a spiral-shaped polymer microdisk cavity by femtosecond laser direct writing via two-photon polymerization of dye-doped resins. This spiral microresonator supports highly directional emission from the notch with a high- Q factor exceeding 1.6\,\times \,10^{3} and a low lasing threshold at room temperature. Our numerical simulation results reveal that clockwise propagating high- Q$ whispering gallery-like modes may couple to the counterclockwise modes and give the directional output. Benefiting from the low cost and good chemical compatibility of polymer materials, the fabrication of such spiral-shaped polymer microlasers with high- $Q$ and unidirectional emission holds great potentials for use as elements of integrated organic optoelectronic devices. [ABSTRACT FROM PUBLISHER]

The emitting properties of fluorophores can be tailored by surface plasmon polaritons (SPPs), which offers the potential to understand the light-matter interactions at the nanoscale, and lays the groundwork for many future applications. As one of the useful features in SPPs—surface plasmon-coupled emission (SPCE) based on the metal gratings; however, the study on its underlying modulation mechanism remains far from satisfactory. That is, how it is affected by the morphology of the grating surfaces. In this letter, we have addressed this question in the dye-coated corrugated silver gratings that possess different periods and depths. It is found that the properties of SPCE are strongly dependent on the dispersion relations of SPPs modulated by the grating periods. [ABSTRACT FROM PUBLISHER]

Presents corrections to the paper, "Metal–insulator transition ofGe–Sb–Te superlattice: An electron counting model study," (Chen, N.-K.), IEEE Trans. Nanotechnol., vol. 17, no. 1, pp. 140–146, Jan. 2018. [ABSTRACT FROM AUTHOR]