Search results for "FABRICATION"
showing 10 items of 460 documents
High efficiency frequency doubling in fully diced LiNbO3ridge waveguides on silicon
2016
Nonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on silicon substrates. Components are carved with only the use of a precision dicing machine without the need for grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 204%/W in a 15 mm long device. The influence of the geometrical non uniformities of waveguides due to fabrication processes is asserted. Characteristics of the components are studied; notably their robustness and tunability versus temperature.
Inverted-opal photonic crystals for ultra light-trapping in solar cells
2010
We investigated a three dimensional inverted opal having the potential to notably increase light-trapping in solar cells. The 3D photonic crystal top layer is an angle- and direction-selective filter, which decreases the acceptance cone of the solar cell. Numerical optimisation methods are used to verify the optical and electrical properties for a large angluar and energy spectrum for a system consisting of an inverted opal on top of a thin crystalline silicon solar cell. It is numerically shown that an inverted opal grown in the Τ - Xdirection might fulfill the requirement for such a filter. An estimate for the theoretically achievable efficiency for nonconcentrated light is presented that…
Reversible Photochemical Control of Doping Levels in Supported Graphene
2017
Controlling the type and density of charge carriers in graphene is vital for a wide range of applications of this material in electronics and optoelectronics. To date, chemical doping and electrostatic gating have served as the two most established means to manipulate the carrier density in graphene. Although highly effective, these two approaches require sophisticated graphene growth or complex device fabrication processes to achieve both the desired nature and the doping densities with generally limited dynamic tunability and spatial control. Here, we report a convenient and tunable optical approach to tune the steady-state carrier density and Fermi energy in graphene by photochemically c…
Advances in Perovskite Solar Cells.
2015
Organolead halide perovskite materials possess a combination of remarkable optoelectronic properties, such as steep optical absorption edge and high absorption coefficients, long charge carrier diffusion lengths and lifetimes. Taken together with the ability for low temperature preparation, also from solution, perovskite-based devices, especially photovoltaic (PV) cells have been studied intensively, with remarkable progress in performance, over the past few years. The combination of high efficiency, low cost and additional (non-PV) applications provides great potential for commercialization. Performance and applications of perovskite solar cells often correlate with their device structures…
Bringing Plasmonics Into CMOS Photonic Foundries: Aluminum Plasmonics on Si$_{3}$N$_{4}$ for Biosensing Applications
2019
We present a technology platform supported by a new process design kit (PDK) that integrates two types of aluminum plasmonic waveguides with Si $_{3}$ N $_{4}$ photonics towards CMOS-compatible plasmo-photonic integrated circuits for sensing applications. More specifically, we demonstrate the fabrication of aluminum slot waveguide via e-beam lithography (EBL) on top of the Si $_{3}$ N $_{4}$ waveguide and an optimized fabrication process of aluminum plasmonic stripe waveguides within a CMOS foundry using EBL. Experimental measurements revealed a propagation length of 6.2 μm for the plasmonic slot waveguide in water at 1550 nm, reporting the first ever experimental demonstration of a plasmon…
Concepts for medium-high to high temperature thermoelectric heat-to-electricity conversion: a review of selected materials and basic considerations o…
2015
Within the last decade, novel materials concepts and nanotechnology have resulted in a great increase of the conversion efficiency of thermoelectric materials. Despite this, a mass market for thermoelectric heat-to-electricity conversion is yet to be opened up. One reason for this is that the transfer of the lab records into fabrication techniques which enable thermoelectric generator modules is very challenging. By closing the gap between record lab values and modules, broad industrial applications may become feasible. In this review, we compare three classes of materials, all designed for medium-high to high temperature applications in the field of waste heat recovery: skutterudites, half…
Multilevel pattern generation by GaN laser lithography: an application to beam shaper fabrication
2006
The new GaN lasers represent a unique combination of compactness, reliability, energy efficiency, and short wavelength. With respect to the previous state of the art in direct laser write lithography, based on gas lasers, this is resulting in a breakthrough, and is opening the way to real desktop micropatterning. The field of diffractive optics can immediately benefit by the availability of a new breed of pattern generators, based on such sources, mainly for fast turnaround device development. This paper presents the technical advantages involved in the use of 405 nm GaN lasers for one-step multilevel patterning. Beam modulation, exposure control and overall process strategy are discussed. …
An Example of Ti:LiNbO3 Device Fabrication: The Mach-Zehnder Electrooptical Modulator
1994
Integrated optics on LiNbO3 has already reached a stage of maturity. Several manufacturers are producing standard and custom devices on LiNbO3 such as high speed (up to 20 GHz) phase and intensity modulators, switching matrices, hybrid optical gyroscopes, etc.1. Two techniques are commonly used to fabricate these devices: titanium indiffusion for 1.3 and 1.5 μm wavelength operation and annealed proton exchange (APE) at 0.8 μm, due to its higher power handling capacity.
Nonstoichiometric silica mask to fabricate reverse proton-exchange waveguides in lithium niobate crystals
2004
Producing channel waveguides requires a photolithographic mask, but the standard technique of using thermally evaporated metal films for proton exchange has proved to be unsuitable for withstanding the rather aggressive process of reverse proton exchange. We report the fabrication of a nonstoichiometric silica mask by ion-plating plasma-assisted deposition. This mask is strong enough to resist both direct and reverse proton exchange and is also compatible with anisotropic dry etching for patterning the mask and with electric field poling. Our technique is a practical alternative to the use of SiO2 sputtered masks.
Vapor-Deposited Perovskites: The Route to High-Performance Solar Cell Production?
2017
Summary High-quality semiconducting perovskites can be easily synthesized through several methods. The ease of fabrication has favored the adoption of lab-scale solution-processing techniques, which have yielded the highest performing devices. Most of these processes, however, are not directly applicable to larger scale and volume preparations, hindering the consolidation and market entry of this technology. Vapor-based methods, a mature technology widely adopted in the coating and semiconductor industry, could change this trend. Their application to perovskite solar cells includes a large amount of fabrication approaches, offering versatility in the employed materials as well as in the cha…