Session Index

This work emphasizes the utilization of SERS-active Ag nanoprisms with sharp tips and edges on Cu2O microspheres for ultra-sensitive antibiotic detection in real-world samples. The proposed SERS substrate endows superior detection performance, including high sensitivity, high enhancement factor of 2.31×10^11, ultra-low limit of detection of 5.80×10^−13 M, superior uniformity and reproducibility with the RSD < 8.31%.

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This study presents a novel approach for the detection of Levodopa (L-dopa) using Surface Plasmon Resonance (SPR) combined with Cyclic Voltammetry (CV). The oxidation reaction of the drug L-dopa is conducted on gold nanoholes by applying EC voltage swing. The nanoholes generate surface plasmon resonance (SPR) and the oxidation process is monitored by SPR spectrum. The results showed that the limit of detection (LOD) using traditional CV reached 1.47 μM, while using EC-SPR, the LOD improved to 1.23 μM.

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Monolayer transition metal dichalcogenides (TMDCs) exhibit ultra-low-threshold excitonic lasers, and optical gain can be achieved near trion emission with lower carrier injection. Therefore, this study aims to utilize the trion emission of monolayer WSe2 as a gain medium to couple with a micro-disk (MD) resonator. By adjusting the diameter of the MD, the resonant wavelength of the trion laser can be matched. Trion emission demonstrates superior gain characteristics, suggesting that trion lasers might have a lower threshold, making them suitable for applications in monolayer TMDCs lasers.

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Active single-mode crystalline fiber can improve the laser performance of its bulk form regarding heat dissipation and pump/signal mode matching. The ultra-broadband emission from Ti:sapphire crystal has advantages compared to semiconductor optical amplifier based tunable lasers for high axial-resolution optical coherence tomography. The study achieved a 99% optical energy transmission through a single-crystalline core and clad Ti:sapphire fiber. The crystalline clad was produced using solid-state growth at 1650 °C for 60 hours. The crystallographic orientation distribution and fluorescence mapping at the fiber end-face were characterized.

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We investigate the hybrid integration of two photonic crystal nanobeam resonator
designs with a Si waveguide, including a nanocavity and a band-edge resonator. Both
integrations demonstrate remarkably high unidirectional coupling efficiencies, exceeding 80%.
In experiments, we have successfully achieved these hybrid integrations using the highly
precise transfer printing method relying on mechanical guidance.

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We present the ultra-thin flexible Ag-NPs/PMMA SERS substrates for the real-time, in-situ antibiotic detection on the fish surface. The used Ag NPs are photoreduced on the nanotip-equipped ferroelectric template and then transferred to a PMMA film. The nanotips on the template surface can produce strong electrostatic field through the lightning rod effect to enhance the photoreduction rate and increase the transfer efficiency. The superior SERS performance includes high sensitivity, the enhancement factor up to 1010, the limit of detection of 2.38×10^-12 M for standard detection and 2.08×10^-10 M for practical detection on irregular fish surface.

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All inorganic perovskite (CsPbBr3) quantum dots are utilized as artificial synaptic devices for biomimetic visual neural systems, effectively integrating optical sensing and electrical memory functionalities. This enables a direct modulation in external optical stimulations, thereby facilitating real-time conversion and transmission in optoelectronic signals. Furthermore, it is feasible to emulate the characteristics of synaptic plasticity by simply applying electrical signals to activate the resistive random-access memory (RRAM) devices.


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In this study, we present a novel approach to enhance the water resistance of CsPbBr3 perovskite quantum dots (PQDs) by encapsulating them within metal-organic frameworks (MOFs). The hierarchical structure consists of a gold thin film on top, CsPbBr3 PQDs embedded within MOFs in the middle layer, and a TiO2/SiO2 distributed Bragg reflector (DBR) on the bottom. Our investigation reveals the presence of strong light-matter coupling and Rabi splitting phenomena within this composite structure. This innovative design offers promising opportunities for developing advanced photonic devices with improved stability and optical properties, opening up new avenues for optoelectronic applications..

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As Si3N4-based photonic integrated circuits emerge as a promising platform, it is important to diagnose their spatial configuration with resolution beyond diffraction limit. Here, we demonstrate a resolution enhancement of hundred-nanometer-diameter Si3N4 nanowires based on photothermal nonlinearity. Our work opens up the avenue for super-resolution imaging of Si3N4 NW by photothermal nonlinearity and SAX subtraction method, which has the potential to exceed the diffraction limit through higher order SAX subtraction.

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The efficient single-photon up-conversion photoluminescence (UCPL) feature was found in 2D lead halide perovskites, and it promises for developing laser cooling devices. In this study, we report the discovery of single-photon up-conversion photoluminescence (UCPL) in 2D lead halide perovskites. The observed UCPL phenomenon involves anti-Stokes photoluminescence (ASPL) and is also referred to as phonon-assisted up-conversion or thermal up-conversion, ASPL removes thermal energy from the system, in turn cooling it. This finding opens up new possibilities for harnessing the unique properties in optoelectronics and photonics applications.

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Photon avalanche (PA) upconversion luminescence (UCL) of rare earth ion-doped upconversion nanoparticles (UCNPs) have attracted great interest due to their extreme nonlinear response to the excitation light intensity via a looping energy transfer mechanism. In this work, we demonstrated the generation of PA UCL of Tm3+-doped NaYF4 UCNPs with an excitation intensity threshold of 6 kWcm-2. Furthermore, we showed that the excitation intensity threshold of the PA UCL of these core UCNPs can be reduced by the guided mode resonance effect generated by a resonant waveguide grating structure.

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Room-temperature phosphorescence (RTP) two-dimensional (2D) organic inorganic hybrid perovskites (OIHPs) that possess efficient triplet energy transfer between inorganic parts and organic cations have been seen as promising materials in optoelectronic devices. However, the development of RTP 2D OIHP-based photomemory has not been explored yet. In this work, the spatially addressable RTP 2D OIHPs based non-volatile flash photomemory is first investigated to explore the function of triplet excitons in elevating the performance of photomemory. Thanks to the triplet excitons generated in RTP 2D OIHP, extremely low photo-programming time of 0.7 ms and multilevel behavior of minimum 7 bits can be achieved.

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We demonstrate a MoS2/Si heterojunction device stacked by utilizing a polymer-assisted all-transfer-printing method. The monolayer MoS2 film is transferred onto the patterned SiO2/p+-Si substrate assisted with PDMS template pad to form a heterojunction. Then, the patterned Pt/Au electrodes defined by photolithography and deposited on the glass substrate are transferred onto MoS2 assisted with water-soluble polyvinyl alcohol (PVA) to form a photodiode. Compared to the sample fabricated by the traditional photolithography process, this proposed method can avoid photoresist residue and organic solvent, and the photoresponsivity increases ~30 times.

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The integration of metasurface and light source has received tremendous attention. However, to obtain efficient beam deflection, some previous studies lack efficiency at large deflection angle, thus limiting the coverage of deflection angle. Here we numerically demonstrate high-efficiency Si-based homo-metagrating that unitize Si substrate to reduce impedance mismatching with InP-based 1550-nm photonic crystal surface emitting laser (PCSEL). We manipulate two degrees of freedom: overall add-on phase and parameters of meta-atoms in a period to optimize the efficiency. We believe the low cost of silicon and the maturity of its fabrication has great advantages for integration within numerous ultracompact optical systems.

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Herein, for the first time, we report efficient N–I–P architecture PeLEDs using solution-processed polyethyleneimine ethoxylated-doped SnO2 (SnO2:PEIE)as an electron transport layer. According to the results, perovskite layer deposited on PEIE-doped SnO2 can achieve better electrical characteristics and crystallinity than pristine SnO2. As a result, PeLEDs based on SnO2:PEIE can achieve a low driving voltage of 1.2 V and an external quantum efficiency of more than 14%.

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Addressing fidelity challenges in photolithographic metalenses is essential for advancing dielectric metalenses adoption in optoelectronic applications. This study presents an innovative reticle modification system guided by a predictive neural-network U-net lithographic model. This correction enables precise control of photoresist dimensions, with a remarkable average deviation of only 0.19% from the target. Additionally, we achieve vertical etch profiles with a high 1:5 aspect ratio across an 8-inch wafer. Consequently, we showcase visible metalenses (2mm diameter) achieving diffraction-limited focusing using DUV KrF 248 nm photolithography. This research bridges semiconductor processes and lens manufacturing, enabling high-volume production of versatile metalenses and metasurface applications.

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We elucidate general scattering relationship between one-dimensional parity-time symmetric unit cells and its resultant photonic crystals. As arbitrary unit cells operated at an exceptional point and broken symmetry phase would always lead to form bands, while ones operated at some symmetry phases with specific transmission phase would construct bandgaps. With an increase of non-Hermiticity, the edges of bands would gradually move toward the center of Brillouin zones.
Any finite periodic systems made of unit cells having exceptional points or broken symmetry would eventually exhibit transmittance of T>1, consistent with an extension of generalized conservation relation proposed by Ref.[1].

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The rise of van der Waals (VDW) materials, especially MoS2 and antimonene, has significant implications for semiconductor technology. MoS2 shows promise as a high-performance semiconductor due to its good electric properties. Antimonene, with much reduced contact resistance when grown on top of MoS2 as compared to traditional metal materials, is a notable approach for future electrode. This work reports the observation of low effective elastic constant of VDW interaction between antimonene and MoS2, to be on the order of 2 × 10^18 N/m^3. This work will trigger future studies of VDW interaction on the contact resistance.

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This study presents a novel approach involving the fabrication of gold (Au) nanohole arrays (ANA) decorated with ring-shaped silver nanoparticles (AgNPs) on a silicon dioxide (SiO2)/silver (Ag) substrate. The surface plasmon resonance coupling in terms of the photoluminescence (PL) reactions of ANA substrates with and without ring-shaped AgNPs is investigated via experiments and numerical simulations. Specifically, the Raman signal of rhodamine 6G (R6G) dye and the PL intensity of DCJTB molecules are significantly enhanced 3.7 and 2.2 times, respectively, compared to those of the bare ANA substrate. Meanwhile, the PL lifetime is reduced by 46.15%.

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In this experiment, we employ the photoalignment material Brilliant Yellow (BY) as the horizontal alignment layer and Polyimide (PI) as the vertical alignment layer in the liquid crystal cell. By exposing BY to polarized ultraviolet light, we can modify the alignment direction of the horizontal layer, consequently altering the arrangement of the liquid crystals. As a result, the liquid crystal molecules on both sides of the Liquid Crystal Networks (LCNs) film exhibit distinct orientations. This alignment can control the bending behavior of the LCN film.

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We successfully synthesize red perovskite quantum dots (QDs) with the CIE color coordinate at (0.7034, 0.2852), which is closely resembling the standard red color (0.708, 0.292) that is specified by Rec.2020. These QDs are mixed with polyvinyl cinnamate (PVCN) to formulate photopatternable thin films. Therefore, we can pattern the films with conventional photolithography techniques. The minimum feature sizes that we achieved is as small as 3.30 μm. The combination of red perovskite QDs with PVCN shows great potential for serving as effective color conversion layers for micro-LEDs in the future.

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In this work, we utilized a novel material called HT-CTP as the sensing material
for a nanoscale vertical pore structure organic semiconductor gas sensor. The experiments
were conducted under controlled conditions with humidity maintained below 15% and an
operating voltage of 5 volts. The results of the experiments revealed that the new material,
when used in the nanoscale vertical pore structure organic semiconductor gas sensor, exhibited
excellent performance in detecting low concentrations of nitrogen oxides with a detection limit
lower than 100 ppb.

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Here, we report a new strategy to sputter ZnGa2O4 thin films (ZGO) on β-Ga2O3 thin films (GaO) and annealed at different temperatures in air to enhance the quality. In this work, the ZGO/GaO structure performances a low dark current and high sensitivity as a UV photodetector. After annealed at 1000 °C in air for 30 mins, the photocurrent of ZGO/GaO significantly increased from 2.85×10-7 to 2.95×10 -4 due to the quality of materials is greatly improved. In addition, ZGO/GaO annealed at 900 °C performances the best sensitivity which as high as 6.42×10 3 .

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This work uses UVC to induce poly-thymine ssDNA dimerization and develops two surface-enhanced Raman scattering methods for validation. One employs self-assembled SERS substrates to measure dry DNA samples, and the other uses gold nanoparticles whose citrate caps have been removed, to sandwich the DNA strands in aqueous solutions. A crucial element in our lab's strong coupling system involves fluorescent molecules embedded in ssDNA. By altering ssDNA conformation with dimerization, it is possible to finely tune the dipole moment orientation of fluorescent molecules, which can enhance its coupling strength to a nanocavity.

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Three conjugated polyelectrolytes (CPEs) PFN-Br, PFN-BF4, and PFN-PF6 were utilized solely for surface modification of zinc oxide nanocrystals (ZnO NCs). ZnO films were smoothened by CPEs that allowed flat deposition of the perovskite absorbing layers. The improved contact between ZnO and perovskite layers was beneficial for reducing leakage current, and the incorporation of CPEs passivated the defects of ZnO films to prolong carrier lifetime of upper CsPbBr3 NCs. The device based on PFN-Br showed the highest device performance, while the one based on PFN-BF4 exhibited better current efficiency over PFN-Br under the low current density below 160 mA/cm2.

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The low filling factor of LCs in the LC-polymer composite systems greatly affects the electro-optic properties of optically isotropic liquid crystal devices. To overcome this issue, we proposed an encapsulated LC which is fabricated through oil-in-water encapsulation, effectively increasing the filling factor by closely packing the capsules. This led to a thin-composite film of nano-size LC encapsulation that reliably switches from isotropic state to anisotropic state in response to a low-voltage electric field, with fast response time and no hysteresis. The improved electro-optic performance of the encapsulated LC device has broad applications in flexible display and tunable photonic systems.

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In this study, we presented the design of active metasurfaces via coherent all-optical control. Two counter-propagating light beams were used to tune the phase gradient of the metasurface, which in term realizes a wide beam steering angle up to 38 degrees. Our scheme provides a versatile strategy toward the realization of high-performance active metasurfaces for beam steering applications.

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Spectral analysis has found extensive use across various applications. Nevertheless, conventional benchtop spectrometers are both bulky and costly. As a result, the miniaturization of spectrometers has emerged as a trend. This work employed UV nanoimprint lithography to pattern a metasurface on a high refractive index TiO2 dielectric material. The optimization of the UV nanoimprint lithography and ICP etching process were key aspects of the fabrication. The spectral responses of the fabricated metasurface units were measured. The metasurface is intended to undergo testing as an on-chip spectrometer, offering a more compact and cost-effective solution.

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We present a novel structure, CsPbBr3 QDs/1T’-MoTe2 MvdWHs, achieved through wafer-scale integration, which exhibits exceptional photogating properties. Under illumination, this structure enhances output photocurrent by 4100% at gate voltage = -7V. Incident photons are absorbed within the QDs, generating photogenerated carriers and creating a photogating effect in the 1T’-MoTe2 layer. The work function mismatch induces an internal electric field at the interface, rapidly bending energy bands, facilitating photogenerated hole transfer to 1T’-MoTe2 under negative back gate voltage, resulting in an overall increase in device photocurrent.

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We presented the analysis of photonic band gap in disordered tetrahedral networks. We showed that the band edges of the gap can be explicitly manipulated by introducing specific types of structural perturbation. The analysis may further provide design and manipulation strategies of engineered photonic band gap based on disordered media.

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Ultrafast lasers with short pulse duration have shown a variety of applications. Carbon nanotubes have shown promising results as saturable absorbers in ultrafast devices, and in the last decade the methods of fabrication and implementation have been vastly improved. In this research we report the fabrication and characterization of a passive modulator using single walled carbon nanotubes in sodium carboxymethyl cellulose as a host polymer. With these results we can confirm if the fabricated modulator can be used as a passive mode locker as a low-cost alternative for a fiber laser at University of Costa Rica.

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In this study, black phosphorus quantum dots (BPQDs) are prepared by the liquid phase exfoliation method, and then introduced to the TiO2 photoanode of the dye-sensitized solar cells (DSSCs). The influence of BPQDs prepared with different ultrasonic vibration times on the photovoltaic conversion efficiency of DSSC is investigated. It is found that the efficiency increases with the vibration time. Moreover, the maximum efficiency is obtained with the vibration time of 15 hours. Compared with the pure TiO2 photoanode, the efficiency of DSSC increases from 4.77% to 5.68% when BPQDs is introduced to the photoanode.

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The pair number of quantum well (QW) and composition of InGaN for InGaN-based multiple QW (MQW) solar cells are investigated and optimized numerically using APSYS. Analysis shows that excessive increase in QW pair number causes worse FF, and excessive increase in indium composition results in the increase of piezoelectric field in QWs, which hinders light-generated carriers from transport. Both result in a decrease in conversion efficiency. This study shows that In0.21GaN MQWs with 18 pairs exhibits the optimal conversion efficiency. A final 31.7% improvement is achieved in this study.

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An external magnetic field enhances the typical photocatalysis mediated by the Au-TiO2 composite nanoparticles in the photocatalytic degradation of methyl orange in water. The applied magnetic field further strengthens the plasmonic enhancements induced by additional visible light illumination of various colors of blue, green, and red, while all processed with UV light.

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