Transmissive nonlocal multilayer thin film optical filter for image differentiation

It is well-known that a Fourier optical system can be used to perform specific computing tasks, such as image differentiation, with a superior speed and power consumption in comparison with digital computers, despite bulky optical components that are often required. Recently, there has been a surge in the interest to design much more compact nanophotonic structures, such as dielectric and metallic thin films, photonic crystals, and metasurfaces with a tailored angle-dependent (nonlocal) optical response, to directly perform image differentiation without additional lenses for Fourier transformation. Here, we present a straightforward platform, a multilayer dielectric thin film optical filter, fabricated using mature wafer-scale thin film deposition technique, with an optimized nonlocal optical response, for isotropic image differentiation in transmission mode for arbitrary input polarization. The proposed thin film filter may be conveniently coated at various transparent surfaces and inserted in machine vision or microscopy systems for enhanced, real-time image processing.

Nonresonant amplification of spin waves through interface magnetoelectric effect and spin-transfer torque

We present a new mechanism for manipulation of the spin-wave amplitude through the use of the dynamic charge-mediated magnetoelectric effect in ultrathin multilayers composed of dielectric thin-film capacitors separated by a ferromagnetic bilayer. Propagating spin waves can be amplified and attenuated with rising and decreasing slopes of the oscillating voltage, respectively, locally applied to the sample. The way the spin accumulation is generated makes the interaction of the spin-transfer torque with the magnetization dynamics mode-selective and restricted to some range of spin-wave frequencies, which is contrary to known types of the spin-transfer torque effects. The interfacial nature of spin-dependent screening allows to reduce the thickness of the fixed magnetization layer to a few nanometers, thus the proposed effect significantly contributes toward realization of the magnonic devices and also miniaturization of the spintronic devices.

IMPROVING RESERVOIR TESTING AND SAMPLING IN H2S CONTAMINATED FLUIDS BY ADAPTING STATE-OF-THE-ART SEMICONDUCTOR THIN FILM TECHNOLOGY FOR DOWNHOLE TESTER TOOLS

Accurate reservoir fluid identification and sampling of hydrogen sulfide (H2S) contaminated fluids is difficult to achieve due its consumption by the interior of downhole tool surfaces prior to sampling or measurement. For low PPM level concentrations, this fact does not change, despite recent tool advances utilizing NACE compliant materials. Consequently, H2S concentrations are typically under-reported which adversely affects production and presents significant health safety and environment concerns. Historically, only sampling bottles have been coated to preserve H2S concentrations during transit to laboratories with a material that is resistant to H2S reactivity to enable more representative measurements. However, only very recent efforts have transitioned the focus toward successfully coating the interior of the tools. This paper details a state-of-the-art technology, initially developed and heavily leveraged from the semiconductor industry. The technology is adapted to coat the interior surfaces of downhole tools with a chemically resistant dielectric thin film. New developments now provide the benefit of the process being safe, able to be performed at atmospheric pressure and temperature conditions, and portable; thus, allowing the coating process to be deployed to field locations. The method involves atomic layer deposition (ALD) technology to be plumbed in directly to a downhole tool and conformally deposit a thin layer (e.g. < 1 micron) of highly durable H2S-resistant sapphire to the entire interior tool surface. An automated procedure has been developed allowing the versatility to accommodate a number of unique geometries inherent of different formation tester configurations. New advances in Quartz Crystal Microbalance sensors are also realized in-situ to optimize (in real-time) the efficiency of the process and ensure uniform and conformal coverage is obtained in the fastest and safest manner. Laboratory testing on a prototype system demonstrated uniform and conformal coverage of a ~ 500 nm thick sapphire film resistant to flaking and scratching. Accelerated lifetime stress testing demonstrated high durability relative to expected tool life. Testing of coated and uncoated tools show the coating is successful at the 50ppm level H2S for up to 4 days. These results are contrasted with similar tool body samples not coated with the H2S-resistant ALD sapphire and subject to the same H2S conditions. To show the coating’s durability, subsequent experiments flowed mud-based drilling fluid through both the tool body and sample chambers, followed by thorough cleaning and successful repeating the same 50ppm H2S test. Exposure of the sapphire coated tool body and sample chambers to various concentrations of H2S demonstrated zero loss. Ultimately this technique represents a new opportunity to gather representative formation samples containing low concentrations of H2S.

Energy Stored and Capacitance of a Circular Parallel Plate Nanocapacitor

Nanocapacitors have received a great deal of attention in recent years due to the promises of high energy storage density as device scaling continues unabated in the nanoscale era. High energy storage capacity is a key ingredient for many nanoelectronic applications in which the significant consumption of energy is required. The electric properties of a nanocapacitor can be strongly modified from the expected bulk properties due to finite-size effects which means that there is an increased need for the accurate characterization of its properties. In this work, we considered a theoretical model for a circular parallel plate nanocapacitor and calculated exactly, in closed analytic form, the electrostatic energy stored in the nanocapacitor as a function of the size of the circular plates and inter-plate separation. The exact expression for the energy is used to derive an analytic formula for the geometric capacitance of this nanocapacitor. The results obtained can be readily amended to incorporate the effects of a dielectric thin film filling the space between the circular plates of the nanocapacitor.

Excitation of Surface Plasmon-Polariton Wave at Both Interfaces of a Silver Thin Film in Two-Layer Kretschmann geometry

In this work, a TiO2-Ag composite structure was fabricated by combination of physical vapor deposition and oblique angle deposition. The nanostructure of the TiO2 columnar thin film was analyzed using the field emission scanning electron microscopy. The excitation of the surface plasmon-polariton waves was studied using an optical setup that is called the two-layer Kretschman geometry. The results showed that two surface plasmon-polariton modes are propagated for TiO2 dielectric thin film at oblique deposition that they are related to metal-air and TiO2 - metal interfaces. The surface plasmon-polariton modes were more localized on interfaces at glancing angles of incident flux vapor. In normal incident of flux vapor only one surface plasmon-polariton mode can be excited at interface of metal-air. The results of this research may be applied in simultaneous sensing of the different molecules, chemical species and nanoparticles with different sizes.