Fabrication of Tapers and Lenslike Waveguides by a Microcontrolled Dip Coating Procedure

A technique for the fabrication of tapered and lenslike waveguides from solution-deposited thin films is described. Using a microprocessor controlled dipping arm, substrates are withdrawn from a solution with a carefully controlled and varying velocity. In this way optical waveguides with regions of varying thickness are deposited. Following the drying and baking of the films, desired structures are obtained in hard inorganic optical waveguides of good optical quality. With refined profile control, we propose to fabricate other optical waveguide components, for example, thin film lenses with this method

Solution Deposited Optical Waveguide Lens

The development of a solution deposited optical waveguide lens, whose focusing effect is produced by an effective index gradient with a hyperbolic secant variation, is described. The lenses are fabricated by a microcontrolled dip coating procedure from colloidal SiO2:TiO2 solutions. Both the design and construction of the lens, along with the analytical and experimental results of the focusing properties, are described. The best lenses had speeds of ~ƒ/10 and focal spots ~1.2 times the diffraction limit at apertures of 2.0 mm

The transition from quantum field theory to one-particle quantum mechanics and a proposed interpretation of Aharonov-Bohm effect

In this article we demonstrate a sense in which the one-particle quantum mechanics (OPQM) and the classical electromagnetic four-potential arise from quantum field theory (QFT). In addition, the classical Maxwell equations are derived from a QFT scattering process, while both classical electromagnetic fields and potentials serve as mathematical tools to approximate the interactions among elementary particles described by QFT physics. Furthermore, a plausible interpretation of the Aharonov-Bohm (AB) effect is raised within the QFT framework. We provide a quantum treatment of the source of electromagnetic potentials and argue that the underlying mechanism in the AB effect can be understood via interactions among electrons described by QFT where the interactions are mediated by virtual photons.Comment: 19 pages, 2 figures. Final published versio

High speed chalcogenide glass electrochemical metallization cells with various active metals

We fabricated electrochemical metallization (ECM) cells using a GaLaSO solid electrolyte, a InSnO inactive electrode and active electrodes consisting of various metals (Cu, Ag, Fe, Cu, Mo, Al). Devices with Ag and Cu active metals showed consistent and repeatable resistive switching behaviour, and had a retention of 3 and >43 days, respectively; both had switching speeds of < 5 ns. Devices with Cr and Fe active metals displayed incomplete or intermittent resistive switching, and devices with Mo and Al active electrodes displayed no resistive switching ability. Deeper penetration of the active metal into the GaLaSO layer resulted in greater resistive switching ability of the cell. The off-state resistivity was greater for more reactive active metals which may be due to a thicker intermediate layer

Chalcogenide Glass-on-Graphene Photonics

Two-dimensional (2-D) materials are of tremendous interest to integrated photonics given their singular optical characteristics spanning light emission, modulation, saturable absorption, and nonlinear optics. To harness their optical properties, these atomically thin materials are usually attached onto prefabricated devices via a transfer process. In this paper, we present a new route for 2-D material integration with planar photonics. Central to this approach is the use of chalcogenide glass, a multifunctional material which can be directly deposited and patterned on a wide variety of 2-D materials and can simultaneously function as the light guiding medium, a gate dielectric, and a passivation layer for 2-D materials. Besides claiming improved fabrication yield and throughput compared to the traditional transfer process, our technique also enables unconventional multilayer device geometries optimally designed for enhancing light-matter interactions in the 2-D layers. Capitalizing on this facile integration method, we demonstrate a series of high-performance glass-on-graphene devices including ultra-broadband on-chip polarizers, energy-efficient thermo-optic switches, as well as graphene-based mid-infrared (mid-IR) waveguide-integrated photodetectors and modulators

Roadmap on chalcogenide photonics

Alloys of sulfur, selenium and tellurium, often referred to as chalcogenide semiconductors, offer a highly versatile, compositionally-controllable material platform for a variety of passive and active photonic applications. They are optically nonlinear, photoconductive materials with wide transmission windows that present various high- and low-index dielectric, low-epsilon and plasmonic properties across ultra-violet, visible and infrared frequencies, in addition to an, non-volatile, electrically/optically induced switching capability between phase states with markedly different electromagnetic properties. This roadmap collection presents an in-depth account of the critical role that chalcogenide semiconductors play within various traditional and emerging photonic technology platforms. The potential of this field going forward is demonstrated by presenting context and outlook on selected socio-economically important research streams utilizing chalcogenide semiconductors. To this end, this roadmap encompasses selected topics that range from systematic design of material properties and switching kinetics to device-level nanostructuring and integration within various photonic system architectures

The promise of chalcogenides

Chalcogenide glasses are attracting significant attention thanks to their mid-infrared transparency and highly nonlinear properties. Nadya Anscombe talks to Dan Hewak from the University of Southampton in the UK

Gallium lanthanum sulphide fibre for active and passive applications

Optical fibres drawn from sulphide-based glasses have been studied now for almost two decades. Initial work began in the 1970s when fibres from glasses based on arsenic sulphide or germanium sulphide rapidly found application as infrared waveguides, providing transmission to beyond 5 microns. In 1993, the first active application of a sulphide glass was demonstrated and measurements on bulk samples of rare-earth doped gallium lanthanum glass showed the possibility of pump efficiencies of over 60%. This lead to widespread activity with the goal of demonstrating a low-loss sulphide glass optical fibre and an 1300 nm optical fibre amplifier. Today, research on several families of sulphide glass, including gallium lanthanum sulphides, germanium sulphides and halide-modified glasses has progressed to the point where several of these materials have been drawn into fibre form. However, application of fibre is critically dependent on the achievement of a low loss single-mode optical fibre which has yet to be achieved. At Southampton, our work has focussed on gallium lanthanum glass and fibre, for both active and passive applications. As part of our ongoing programme, optical, thermal and mechanical properties of these glasses are under study. In parallel with this, fibre drawing is being refined in a quest for practical fibres. Over the past year, improvements have been made in understanding and eliminating the sources of loss in these glasses. In this paper, we describe the current specifications of fibres based on this material group. Recent progress in several applications, in particular those extending into the infrared will be reported and the prospects for a future generation of sulphide-fibre based devices examined