Phase-change chalcogenide glass metamaterial

Combining metamaterials with functional media brings a new dimension to their performance. Here we demonstrate substantial resonance frequency tuning in a photonic metamaterial hybridized with an electrically/optically switchable chalcogenide glass. The transition between amorphous and crystalline forms brings about a 10% shift in the near-infrared resonance wavelength of an asymmetric split-ring array, providing transmission modulation functionality with a contrast ratio of 4:1 in a device of sub-wavelength thickness.Comment: 3 pages, 3 figure

Spectroscopic and thermal properties of GeS2-based chalcohalide glasses

The low phonon energy of germanium sulphide glasses makes them ideal candidates as hosts for 1.3µm fibre amplifier applications. However, the GeS2 glass host suffers from a major drawback of poor rare-earth ion solubility. In an efficient device, the solubility of Pr ions has to be enhanced, without adversely affecting either the thermal or the spectroscopic properties of the glass. In the present investigation, we report the synthesis and optical properties of modified GeS2-based chalcohalide glasses with excellent thermal characteristics suitable for drawing low-loss optical fibres

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

Concentration dependence of the fluorescence decay profile in transition metal doped chalcogenide glass

Abstract In this paper we present the fluorescence decay profiles of vanadium and titanium doped gallium lanthanum sulphide (GLS) glass at various doping concentrations between 0.01 and 1% (molar). We demonstrate that below a critical doping concentration the fluorescence decay profile can be fitted with the stretched exponential function: exp [-(t/τ) β ], where τ is the fluorescence lifetime and β is the stretch factor. At low concentrations the lifetime for vanadium and titanium doped GLS was 30 μs and 67 μs respectively. We validate the use of the stretched exponential model and discuss the possible microscopic phenomenon it arises from. We also demonstrate that above a critical doping concentration of around 0.1% (molar) the fluorescence decay profile can be fitted with the double exponential function: a*exp-(t/τ 1 )+ b*exp-(t/τ 2 ), where τ 1 and τ 2 are characteristic fast and slow components of the fluorescence decay profile, for vanadium the fast and slow components are 5 μs and 30 μs respectively and for titanium they are 15 μs and 67 μs respectively. We also show that the fluorescence lifetime of vanadium and titanium at low concentrations in the oxide rich host gallium lanthanum oxy-sulphide (GLSO) is 43 μs and 97 μs respectively, which is longer than that in GLS. From this we deduce that vanadium and titanium fluorescing ions preferentially substitute into high efficiency oxide sites until at a critical concentration they become saturated and low efficiency sulphide sites start to be filled

Structural and spectral characterisation of Er3+ and Nd3+ doped Ga-La-S-Se glasses

In this work, the spectroscopy of Er3+ and Nd3+ doped Se-GLS glasses was studied. A structural comparison between doped and non-doped samples was done to assess the differences between the glasses. For this comparison, Raman spectroscopy and thermal analysis were employed. The spectral properties of the samples were studied in order to identify the mechanisms responsible for quenching the fluorescence lifetime of the dopants. In particular, cross-relaxation and concentration quenching were observed in Nd3+ doped samples, whilst co-operative upconversion, radiation trapping and concentration quenching were observed in Er3+ doped samples. The results obtained demonstrated the fundamental role of the phonon energy in the mechanism of fluorescence. The low phonon energy of chalcogenides decreased the rate of non-radiative processes promoting co-operative upconversion. This effect could be exploited to design new lasers and sensitizers for solar energy harvesters

Proposal for an Er3+-doped chalcogenide glass fiber upconversion laser operating at 980 nm and pumped at 1480 nm

We propose a novel fiber upconversion laser operating at 980 nm and pumped at 1480 nm, which will allow remote optical pumping of erbium-doped optical amplifiers, From the measured spectroscopy, we show Er3+-doped gallium lanthanum sulphide glass to be a potential host for such a 1480-nm/980-nm upconversion laser. The small-signal gain is analyzed numerically and the lasing possibilities are discussed

Spectral properties of Er3+-doped gallium lanthanum sulphide glass

The spectral properties of chalcogenide glass 0.7Ga(2)S(3):0.3La(2)S(3) (Ga:La:S) doped with Er3+ are presented and discussed. Emission and adsorption spectra and lifetimes of energy levels have been measured. The 2.7 mu m emission of Er3+ has been observed from chalcogenide glass for the first time. Radiative and non-radiative transition rates are calculated and compared with the measured lifetimes of interesting energy levels. Comparing this glass with Er3+-doped silica glasses, it is shown that the absorption and emission cross-sections of Er3+-doped Ga:La:S are around 2.5 times higher, radiative transitions rates are around five times higher due to its higher refractive index, while multiphonon non-radiative decay rates are around three orders lower due to its much lower phonon energy. Furthermore, the inverse energy transfer process in Er3+:Ga:La:S glass may have significant implications for the operation of Er3+:Ga:La:S devices. These spectral properties, along with the higher solubility for rare earth-ions in Ga:La:S, make this glass a good candidate for new applications

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

New ultraviolet monitoring technology.

There is a growing awareness of the hazards of ultraviolet (UV) radiation to the health of the community and to our environment's integrity. There is a need for monitoring this hazard. Until recently, UV radiation sensors tended to be relatively expensive. However, as a result of the introduction of mass-produced GaAs photodiodes in the late 1980s, UV radiation now can be measured more accurately, cost-effectively and conveniently. A new, low-cost sensor is available with a wavelength tailored to the skin's erythmal response without additional complex circuitry or filter elements; it can be used in a variety of settings