Phys.org October 16, 2024 Thin-film lithium niobate is a promising platform for on-chip photon-pair generation through spontaneous parametric down-conversion (SPDC). However, device implementation faces practical challenges. Periodically poled lithium niobate (PPLN) suffers from poor fabrication reliability and device repeatability, while conventional modal phase matching (MPM) methods yield limited efficiencies. Researchers in Singapore introduced a layer-poled lithium niobate (LPLN) nanophotonic waveguide that significantly enhanced nonlinear interactions for MPM, and achieved normalized second-harmonic generation (SHG) conversion efficiency. Through a cascaded SHG and SPDC process, they demonstrated photon-pair generation with a normalized brightness in a 3.3 mm long LPLN waveguide. According to the […]
Tag Archives: S&T Singapore
Printing 3D photonic crystals that completely block light
Nanowerk September 12, 2024 Fabricating photonic crystals with a complete photonic bandgap in the visible spectrum presents at least two important challenges: achieving a material refractive index > ~2 and a three-dimensional patterning resolution better than ~280 nm. Researchers in Singapore developed a titanium ion-doped resin (Ti-Nano) for high-resolution printing by two-photon polymerization lithography. After printing, the structures were heat-treated in air to induce lattice shrinkage and produced titania nanostructures. The attainted three-dimensional photonic crystals with patterning resolution as high as 180 nm and refractive index of 2.4–2.6. Optical characterization revealed ~100% reflectance within the photonic crystal bandgap in the visible range. They showed […]
Ultrathin quantum light sources: Scientists show excitonic interactions boost efficiency of entangled photon generation
Phys.org August 19, 2024 Researchers in Singapore have showed that the efficiency of spontaneous parametric down-conversion (SPDC) could be improved by harnessing many-body excitonic interactions present in the non-linear optical crystal. They showed that excitonic resonances and interexciton transitions could enhance the probability of SPDC. They benchmarked their ab initio many-body calculations using experimental polar plots of second harmonic generation in NbOI2, demonstrating the relevance of excitons in the nonlinear response. A strong double-exciton resonance in 2D NbOCl2 led to significant enhancement in the second order susceptibility. According to the researchers their work paves the way for the realization of […]
Researchers develop a computer from an array of VCSELs with optical feedback
Phys.org February 23, 2024 Vertical cavity surface-emitting (VCSEL) arrays offer an attractive platform to develop a photonic Ising computer due to their scalability and compact physical size. Researchers in Singapore computationally investigated the performance of this approach by extending the spin-flip model to describe a system of mutually injection locked VCSELs for 2-, 3-, and 4-bit Ising problems. Numerical simulations demonstrated that the modeled system solved the given Ising problems significantly better than chance, with critical parameters in the model identified as crucial for achieving an unbiased Ising solver. According to the researchers the quantum well gain anisotropy parameter as […]
Novel liquid metal circuits for flexible, self-healing wearables
Nanowerk October 2, 2023 Present integrated stretchable electronics easily suffer from electrical deterioration and face challenges in forming robust multilayered soft-rigid hybrid configurations. Researchers in Singapore have developed a bilayer liquid-solid conductor (b-LSC) with amphiphilic properties that reliably interfaces with both rigid electronics and elastomeric substrates. The top liquid metal could self-solder its interface with rigid electronics at a resistance 30% lower than the traditional tin-soldered rigid interface. The bottom polar composite comprising liquid metal particles and polymers could not only reliably interface with elastomers but also help the b-LSC heal after breakage. The b-LSC fabrication could be scaled up […]
Scientists develop 2D nanosheets for sustainable carbon capture
Phys.org July 6, 2023 Mica, a commonly occurring mineral, has significant potential for various applications due to its unique structure and properties. However, due to its non-Van Der Waals bonded structure, it is difficult to exfoliate mica into ultrathin nanosheets. Researchers in Singapore characterized exfoliated 2D mica nanosheets (eMica nanosheets) by various techniques, and their ability to capture CO2 was tested by thermogravimetric analysis (TGA). Their results showed an 87% increase in CO2 adsorption capacity with eMica nanosheets compared to conventional mica. Further characterization by Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), as well as first-principles calculations, showed […]
Innovative paper-like, battery-free, AI-enabled sensor for holistic wound monitoring
Nanowerk June 26, 2023 Researchers in Singapore developed a paper-like battery-free in situ AI-enabled multiplexed (PETAL) sensor for holistic wound assessment by leveraging deep learning algorithms. This sensor consisted of a wax-printed paper panel with five colorimetric sensors for temperature, pH, trimethylamine, uric acid, and moisture. Sensor images captured by a mobile phone were analyzed by neural network–based machine learning algorithms to determine healing status. For ex situ detection via exudates collected from rat perturbed wounds and burn wounds, the PETAL sensor could classify healing versus nonhealing status with an accuracy as high as 97%. With the sensor patches attached […]
Scientists demonstrate quantum recoil for the first time, paving the way for precise X-ray imaging
Phys.org January 19, 2023 More than 80 years after quantum recoil was proposed researchers in Singapore have demonstrated the phenomenon of quantum recoil showing that it is observable at room temperature. By scattering free electrons off the periodic two-dimensional atomic sheets of van der Waals materials in a tabletop platform, they showed that the X-ray photon energy is accurately predicted only by quantum recoil theory, that it can be enormous, to the point that a classically predicted X-ray photon is emitted as an extremely low-energy photon. According to the researchers quantum recoil is a means of precision control over outgoing […]
Researchers invent self-charging, ultra-thin device that generates electricity from air moisture
Science Daily August 17, 2022 The current moisture-driven energy generation (MEG) materials and devices only establish moisture-driven energy interaction during water sorption in specific configurations, and conversion is eventually ceased by saturated water uptake. Researchers in Singapore have developed an asymmetric hygroscopic structure (AHS) that simultaneously achieves energy harvesting and storage from moisture absorption. The AHS was constructed by the asymmetric deposition of a hygroscopic ionic hydrogel over a layer of functionalized carbon. Water absorbed from the air creates wet-dry asymmetry across the AHS and hence an in-plane electric field. The asymmetry could be perpetually maintained even after saturated water […]
Customized magneto-optical trap allows for cooling indium atoms to near absolute zero
Phys.org July 13, 2022 Cooling some atomic gases confers unique and sometimes useful properties to the atoms. The use of magneto optical traps (MOTs) for cooling works on only a small number of atomic groups on the periodic table. Rather than a ground state transition, researchers in Singapore used a transition from a more long-lived metastable state in their MOT. This required modifying it to work with just indium atoms. Once the reconfiguration was completed, the researchers created a cloud made up of more than 500 million indium-115 atoms in their MOT and cooled the atoms to approximately 1 mK […]