Graphene Photonics and Optoelectronics

The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. So far, the main focus has been on fundamental physics and electronic devices. However, we believe its true potential to be in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, and the linear dispersion of the Dirac electrons enables ultra-wide-band tunability. The rise of graphene in photonics and optoelectronics is shown by several recent results, ranging from solar cells and light emitting devices, to touch screens, photodetectors and ultrafast lasers. Here we review the state of the art in this emerging field.Comment: Review Nature Photonics, in pres

Heteroepitaxial growth of ZnO branches selectively on TiO2 nanorod tips with improved light harvesting performance

A seeded heteroepitaxial growth of ZnO nanorods selectively on TiO2 nanorod tips was achieved by restricting crystal growth on highly hydrophobic TiO2 nanorod film surfaces. Intriguing light harvesting performance and efficient charge transport efficiency has been found, which suggest potential applications in photovoltaics and optoelectronics

Electron, hole, and exciton spectra in a quantum wire crossing the quantum well

The electron, hole, and exciton energy spectra are calculated within the effective mass and rectangular potential approximations for a combined semiconductor nanoheterosystem consisting of a cylindrical semiconductor quantum wire crossing the plane quantum well. It is shown that the electron (hole) in such a system is characterized by five quantum numbers related to five degrees of freedom for a quasiparticle. The dependences of the quasiparticle energy on the quantum wire radius and the quantum well width are researched

Analysis of the applicability of singlemode optical fibers for measurement of deformation with distributed systems BOTDR

Distributed optical fiber sensors allow monitoring physical effects across the whole cable. The paper presents results obtained from the performed tests and shows that single mode fibers can provide analyses of the deformation changes, when distributed optical systems BOTDR used. We used standard optical fiber G.652.D with primary and secondary protected layers and specialized cable SMC-V4 designed for this purpose. The aim was to compare the deformation sensitivity and determine which fiber types are the best to use. We deformed the fiber in the longitudinal and transverse directions and mechanically stressed in orthogonal directions to find how to localize optical fibers. They could be deployed in real use. For achieving optimal results of mechanical changes and acting forces, sensor fibers have to be located carefully

An Environmentally Stable and Lead-Free Chalcogenide Perovskite

Organic-inorganic halide perovskites are intrinsically unstable when exposed to moisture and/or light. Additionally, the presence of lead in many perovskites raises toxicity concerns. Herein is reported a thin film of BaZrS3, a lead-free chalcogenide perovskite. Photoluminescence and X-ray diffraction measurements show that BaZrS3 is far more stable than methylammonium lead iodide (MAPbI3) in moist environments. Moisture- and light-induced degradations in BaZrS3 and MAPbI3 are compared by using simulations and calculations based on density functional theory. The simulations reveal drastically slower degradation in BaZrS3 due to two factors - weak interaction with water, and very low rates of ion migration. BaZrS3 photo-detecting devices with photo-responsivity of ~46.5 mA W-1 are also reported. The devices retain ~60% of their initial photo-response after 4 weeks in ambient conditions. Similar MAPbI3 devices degrade rapidly and show ~95% decrease in photo-responsivity in just 4 days. The findings establish the superior stability of BaZrS3 and strengthen the case for its use in optoelectronics. New possibilities for thermoelectric energy conversion using these materials are also demonstrated

Optical Birefringence Fiber Temperature Sensors in the Visible Spectrum of Light

This article describes experimental tests to determine PM fibers Panda style responses to a thermal source with different initial temperature. The aim of this study was to determine the sensitivity of a polarization maintaining fiber to the radiating heat, and to upgrade the space configuration and time response when using the 635 nm light. The sensitivity of the polarization maintaining fiber during excitation of both polarization modes is the principle of this sensor function. This excitation is caused by temperature change and by absorption of thermal radiation. This mechanism is used as an indicator for detection of temperature field disturbance. This article also provides links to previously published results and compares them to the results in this article