Mark Hughes

University of Salford · Department of Physics

Reaction order in Bi-doped oxide glasses depends on the optical basicity of the glass host. Red and NIR photoluminescence (PL) bands result from Bi²⁺ and Bi n clusters, respectively. Very similar centers are present in Bi- and Pb-doped oxide and chalcogenide glasses. Bi-implanted and Bi melt-doped chalcogenide glasses display new PL bands, indicati...

The authors describe the fabrication of buried waveguides in a highly nonlinear chalcogenide glass, gallium lanthanum sulfide, using focused femtosecond laser pulses. Through optical characterization of the waveguides, they have proposed a formation mechanism and provide comparisons to previous work. Tunneling has been identified as the dominant no...

We report emission from a bismuth doped chalcogenide glass which is flattened, has a full width at half maximum (FWHM) of 600 nm, peaks at 1300 nm and covers the entire telecommunications window. At cryogenic temperatures the FWHM reaches 850 nm. The quantum efficiency and lifetime were as high as 32% and 175 μs, respectively. We also report two ne...

We report the effects of high pressure, up to 10.45 GPa, on the photoluminescence of Bi-doped yttria-alumina-silica glass under 532 nm excitation. We identify three emission bands attributed to Bi³⁺, Bi⁺ and a NIR emitting Bi centre, BiNIR. As the pressure is increased up to ∼6 GPa, an irreversible discontinuity in the trend for emission band energ...

Erbium implanted silicon as a quantum technology platform has both telecommunications and integrated circuit processing compatibility. In Si implanted with Er to a concentration of 3x10^17 cm^3 and O to a concentration of 10^20 cm^3, the electron spin coherence time, T2, and the spin-lattice relaxation time, T1, were measured to be 7.5 ls and ~1 ms...

Erbium-implanted silicon is promising for both photonic and quantum-technology platforms, since it possesses both telecommunications and integrated-circuit processing compatibility. However, several different Er centers are generated during the implantation and annealing process, the presence of which could hinder the development of these applicati...

Erbium implanted silicon as a quantum technology platform has both telecommunications and integrated circuit processing compatibility. In Si implanted with Er to a concentration of 3 × 10¹⁷ cm⁻³ and O to a concentration of 10²⁰ cm⁻³, the electron spin coherence time, T2, and the spin-lattice relaxation time, T1, were measured to be 7.5 μs and ∼1 ms...

Quantum technology (QT) platforms with telecommunications and integrated circuit (IC) processing compatibility have important implications for the long-distance transfer of quantum information, and QT platforms based on ion implantation are inherently scalable. Here we establish the potential of Er implanted Si as a scalable QT platform with teleco...

Er implanted Si is a candidate for quantum and photonic applications; however, several different Er centres are generated, and their symmetry, energy level structure, magnetic and optical properties, and mutual interactions have been poorly understood, which has been a major barrier to the development of these applications. Optically modulated magn...

This study reports the effect of an increasing ion dose on both the electrical activation yield and the characteristic properties of implanted bismuth donors in silicon. A strong dependence of implant fluence is observed on both the yield of bismuth donors and the measured impurity diffusion. This is such that higher ion concentrations result in bo...

The suitability of ion‐implanted bismuth donors in silicon as a high‐quality platform for quantum technologies is demonstrated in article number 1800038 by Steven Clowes and co‐workers. The cover image represents both the bismuth ion beam and the active bismuth donors incorporated within a silicon lattice. Additionally, an artistic depiction of res...

This study reports on high energy bismuth ion implantation into silicon with a particular emphasis on the effect that annealing conditions have on the observed hyperfine structure of the Si:Bi donor state. A suppression of donor bound exciton, D0X, photoluminescence is observed in implanted samples which have been annealed at 700 °C relating to the...

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; bo...

Silicon underpins microelectronics but lacks the photonic capability needed for next-generation systems and currently relies on a highly undesirable hybridization of separate discrete devices using direct band gap semiconductors. Rare-earth (RE) implantation is a promising approach to bestow photonic capability to silicon but is limited to internal...

We report the lattice site and symmetry of optically active Dy³⁺ and Tm³⁺ implanted Si. Local symmetry was determined by fitting crystal field parameters (CFPs), corresponding to various common symmetries, to the ground state splitting determined by photoluminescence measurements. These CFP values were then used to calculate the splitting of every...

Carrier-type reversal to enable the formation of semiconductor p-n junctions is a prerequisite for many electronic applications. Chalcogenide glasses are p-type semiconductors and their applications have been limited by the extraordinary difficulty in obtaining n-type conductivity. The ability to form chalcogenide glass p-n junctions could improve...

The impact of Bi implantation on the conductivity and the thermopower of amorphous chalcogenide films is investigated. Incorporation of Bi in Ge-Sb-Te and GeTe results in enhanced conductivity. The negative Seebeck coefficient confirms onset of the electron conductivity in GeTe implanted with Bi at a dose of 2x1016 cm-2. The enhanced conductivity i...

We report amorphous GaLaSO-based resistive switching devices, with and without Pb-implantation before deposition of an Al active electrode, which switch due to deposition and dissolution of Al metal filaments. The devices set at 2–3 and 3–4 V with resistance ratios of 6 × 104 and 3 × 109 for the unimplanted and Pb-implanted devices, respectively. T...

We fabricated a Ti/Pd asymmetrically contacted single carbon nanotube (CNT) field-effect transistor (FET) with split-gates. Transfer characteristics can be explained if the Schottky barrier for electrons is lower at the Pd contact than it is at the Ti contact. Strong rectification is observed when the gates are unbiased, and the rectification direc...

We report waveguides in Ni-doped Li2O–Ga2O3–SiO2 (Ni:LGS) glass and glass–ceramic (GC) fabricated with a femtosecond (fs) laser with repetition rate of 1 kHz. When the glass is annealed to form a GC, the waveguides are erased. However, in the GC the waveguides are not erased by annealing. In Ni:LGS GC a 415 nm absorption band was created by fs lase...

A review paper in progress

Asymmetric contacts or split gate geometries can be used to obtain rectification, electroluminescence (EL) and photocurrent from carbon nanotube field effect transistors. Here, we report devices with both split gates and asymmetric contacts and show that device parameters can be optimised with an appropriate split gate bias, giving the ability to s...

Doping of amorphous chalcogenide films of rather dissimilar bonding type and resistivity, namely, Ga-La-S, GeTe, and Ge-Sb-Te by means of ion implantation of bismuth is considered. To characterize defects induced by ionbeam implantation space-charge-limited conduction and capacitance-voltage characteristics of amorphous chalcogenide/silicon heteroj...

We fabricated a Ti/Pd asymmetrically contacted single carbon nanotube (CNT) field-effect transistor (FET) with split-gates. Transfer characteristics can be explained if the Schottky barrier for electrons is lower at the Pd contact than it is at the Ti contact. Strong rectification is observed when the gates are unbiased, and the rectification direc...

A single carbon nanotube diode is reported, with Ti and Pd contacts, and split gates. Without gate bias the device displays strong rectification, with a leakage current (I0) of 6 × 10-16 A, and an ideality factor (η) of 1.38. When the gate above the Ti contact is biased negatively the diode inverts. When positive bias is then applied to the gate ab...

We inscribed relief diffraction gratings with periods of 6, 14, and 24 μm into the surface of Ge 15 Ga 3 Sb 12 S 70 bulk glass by the material’s ablation using a femtosecond λ = 800 nm Ti:sapphire pulsed laser. The laser writing was done with sample implemented on a computer-controlled stage employing surface-to-beam alignment, laser power, and ras...

Direct laser writing has been already demonstrated for the fabrication of under surface "buried" 3D mid-IR waveguides in chalcogenide glasses by employing a large photo-induced refractive index change in the features formed in the path of the focused beam from a short pulse laser. In this paper, we report on direct laser writing of relief diffracti...

The internal quantum efficiencies under sunlight and laser excitation were measured directly by an integrating sphere method for tellurite, borosilicate and fluoride glasses. The radiative quantum efficiency was also obtained by Judd–Ofelt analysis. The radiative quantum efficiency was almost 100% for tellurite and fluoride glasses and 50% for boro...

The absorption and fluorescence characteristics of Er doped and Nd, Er codoped fluoride glasses were investigated under illumination of the simulated sunlight, laser or a monochromatic light filtered from a Xe lamp. Er was used as a sensitizing agent enhancing the energy conversion and the emission efficiency of Nd ions in fluoride glass intended f...

In this paper we report emission from Bi doped gallium lanthanum sulphide (Bi:GLS) glass with a full width at half maximum (FWHM) of 600 nm which is flattened and covers the entire telecommunications window. The excitation wavelength of this emission was 1020 nm, the quantum efficiency (QE) was 17%, the lifetime was 160 mus and product of the emiss...

Vanadium doped chalcogenide glass has potential as an active gain medium, particularly at telecommunications wavelengths. This dopant has three spin allowed absorption transitions at 1100, 737 and 578nm, and a spin forbidden absorption transition at 1000nm. X-ray photoelectron spectroscopy indicated the presence of vanadium in a range of oxidation...

In this work we make a comparison between the spectroscopy of bismuth-doped lead–aluminum–germanate (Bi:PAG) glass and bismuth-doped yttrium–aluminum–silicate (Bi:YAS) glass. We report the variation in Bi absorption, emission and lifetime as the PbO, Bi2O3 and Y2O3 contents of the two glass systems were varied. As PbO and Y2O3 contents were increas...

Nd-doped SiO2–B2O3–Na2O–Al2O3–CaO–ZrO2 glasses were prepared and optical properties such as absorption, lifetime and quantum efficiencies (QEs) of the emission were characterized. QE measurement system with natural sunlight as an excitation source was constructed. The radiative QE (ηr) obtained from the lifetime by Judd–Ofelt analysis, directly mea...

The upconversion efficiency depends on the pump power density. Materials exhibiting a high upconversion efficiency under high pump power density do not necessarily have a reasonable upconversion efficiency under the pump power density around that of the concentrated sunlight. Also, materials which have an upconversion efficiency not so high under h...

We report the compositional dependence of absorption, emission, decay constant and quantum efficiency (QE) of GeO2:Al2O3:PbO:Bi2O3 glass with the aim of finding the composition most suitable for a laser gain medium. As the Bi2O3 content was varied we observed a non-monotonic variation in absorption spectrum. The optimized composition was 87.4GeO2:6...

In this paper we present the development process of glass based on bismuth and aluminum co-doped germanate (GAB) glass. We found the addition of PbO to this glass (GAPB glass) increased the quantum efficiency (QE). Excitation of GAPB glass at 808nm produced emission peaking at 1230nm with a width of 260nm, indicating the glass may be useful as a br...

The quantum efficiencies of the emission from the (4)F(3/2)(R) level of Nd doped in tellurite glass were measured with an integrating sphere using natural sunlight(eta(ns)), simulated sunlight (eta(ns)), and 808 nm laser light (eta(808)), respectively. The radiative quantum efficiency (eta(r)) was estimated from the fluorescence lifetime (tau(f)) a...

The efficiency of energy transfer from Cr to Nd in silicate glasses has been examined in order to develop a gain medium for high-efficiency solar pumped fiber lasers (SPFLs). The internal quantum efficiency (QE) of the emission from the 4T2 state of Cr in Cr-doped glasses and from the 4F3/2 state of Nd in Nd-doped and Nd,Cr codoped glasses was meas...

The single crystal growth conditions and spectroscopic characterization of Ni-doped MgGa2O4 with inverse-spinel structure crystal family are described. Single crystals of this material have been grown by floating zone method. Ni-doped MgGa2O4 single crystals have broadband fluorescence in the 1100–1600nm wavelength range, 1.6ms room temperature lif...

The quantum efficiency of Nd3+-doped ZBLAN glass under sunlight excitation was measured as more than 70 %, which would be due to the low loss in the VIS-UV region and phonon energy of the glass.

The quantum efficiency of Nd3+-doped tellurite glass which is made from high-purity TeO2 under sunlight excitation was measured as more than 55%, which is high enough for solar pumped laser.

The impact of Bi implantation on the conductivity and the thermopower of GeTe, Ge–Sb–Te, and Ga–La–S films is investigated. The enhanced conductivity appears to be notably sensitive to a dose of an implant. Incorporation of Bi in amorphous chalcogenide films at doses up to 1 × 10 15 cm −2 is seen not to change the majority carrier type and activati...

Chalcogenides are compounds formed predominately from one or more of the chalcogen elements; sulphur, selenium and tellurium. Although first studied over fifty years ago, interest in chalcogenide glasses has, over the past few years, increased significantly as glasses, crystals and alloys find new life in a wide range of photonic devices. This chap...

We fabricated three series of glasses in which the Y2O3, Bi2O3 and Al2O3 contents of Bi-doped Y2O3:Al2O3:SiO2 glass were varied. We optimized the content of each component based on quantum efficiency (QE) and other optical properties. The strength of the Bi absorption bands decreased with increasing Y2O3 content. The optimized composition was: 63.5...

Nonlinear spectral broadening to 200 nm , from an initial width of 50 nm , has been demonstrated in gallium lanthanum sulphide glass waveguides from 1540 nm , 200 fs pulses at 30 nJ /pulse. A formation mechanism is presented for these femtosecond laser written waveguides, based on optical characterization and comparisons to previous work. Two diffe...

In this paper we present the development process of a glass based on bismuth and aluminum co-doped germanate (GAB) glass. Other workers have demonstrated broadband optical gain in GAB glass. We found the addition of PbO to this glass (GAPB glass) increased the quantum efficiency (QE). Excitation of GAPB glass at 808 nm produced emission peaking at...

Titanium-doped gallium lanthanum sulfide (Ti:GLS) and gallium lanthanum oxysulfide (Ti:GLSO) glasses have an absorption band at ∼ 500 – 600 nm that cannot be fully resolved because of its proximity to the band edge of the glass. At concentrations > 0.5 % a shoulder at 980 nm is observed in Ti:GLS but not in Ti:GLSO. The emission spectra of Ti:GLS a...

We fabricated a series of glasses with the composition 94.7 - χ GeO 2 - 5 Al 2 O 3 - 0.3 Bi 2 O 3 - χ PbO ( χ = 0 – 24 mol. % ) . Characteristic absorption bands of bismuth centered at 500, 700, 800, and 1000 nm were observed. Adding PbO was found to decrease the strength of bismuth absorption. The addition of 3%–4% PbO resulted in a 50% increase i...

This thesis focuses on two different, but complementary, aspects of the modification of gallium lanthanum sulphide (GLS) glasses. Firstly the addition of transition metal ions as dopants is examined and their potential for use as active optical materials is explored. It is also argued that the spectroscopic analysis of transition metal ions is a us...

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], whe...

Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 730, and 1155 nm identified by photoluminescence excitation measurements. Broad photoluminescence, with a full width at half maximum of ∼500 nm , is observed peaking at 1500 nm when exciting at 514, 808, and 1064 nm . The fluorescence lifetime and quantu...

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/tau)beta]...

In this paper we report the spectroscopic data for samples of 0.031% iron, 0.017% nickel, 0.01% chromium and 0.017% cobalt (molar) doped gallium lanthanum sulphide (GLS) glass. Photoluminescence (PL) with a full width half maximum (FWHM) of around 500 nm and peaking between 1120 nm and 1460 nm is observed when excited using wavelengths of 850 nm an...

The infrared (IR) spectrum is of significant importance in many defence applications including free-space communication, thermal imaging and chemical sensing. The materials used in these applications must exhibit a number of suitable properties including mid-IR transparency, rare-earth solubility and low optical loss. When moving towards miniaturis...

The infrared (IR) spectrum is of significant importance in many defence applications including free-space communication, thermal imaging and chemical sensing. The materials used in these applications must exhibit a number of suitable properties including mid-IR transparency, rare-earth solubility and low optical loss. When moving towards miniaturis...

The use of rare-earth ion dopants to obtain near-infrared (NIR) emission and lasing in glass fibres and waveguides is well known. However, due to the intrinsic nature of the spin-forbidden 4f-4f transitions the emission is generally only tuneable over a narrow spectral range (~50nm). The development of a broadband NIR source or tuneable laser would...

The use of transition metal ions to obtain broadband emission and widely tuneable lasers is widely known. In particular, the incorporation of such ions into crystalline hosts has resulted in a wide number of lasers covering the spectral region from ~750nm to ~3µm. The use of metal ions in glass hosts for laser applications has however been limited...