Publications

See a list of publications below or visit the Photonics academic staff page and click on a particular  member of staff to access their personal web page, which includes a list of their own publications.

Search or filter publications

Filter by type:

Filter by publication type

Filter by year:

to

Results

  • Showing results for:
  • Reset all filters

Search results

  • Conference paper
    Kumar S, Lockwood N, Ramel MC, Correia T, Ellis M, Alexandrov Y, Andrews N, Patel R, Bugeon L, Dallman MJ, Brandner S, Arridge S, Katan M, McGinty J, Frankel P, French PMWet al., 2016,

    In vivo multiplexed OPT and FLIM OPT of an adult zebrafish cancer disease model

    We report angular multiplexed OPT and FLIM OPT applied to in vivo imaging of cancer and FRET biosensors in adult zebrafish. Multiple-spectral 3-D datasets of entire adult zebrafish can be acquired in 3 minutes.
  • Conference paper
    Friddin MS, Bolognesi G, Elani Y, Brooks NJ, Law RV, Seddon JM, Neil MAA, Ces Oet al., 2016,

    Light-driven drag and drop assembly of micron-scale bilayer networks for synthetic biology

    , Pages: 545-546

    We have developed a new method to assemble single- or multi-layered networks of droplet interface bilayers (DIBs) from cell-sized droplets using a single beam optical trap (optical tweezers). The novelty of our approach is the ability to directly trap the microdroplets with the laser and manipulate them in 3D to construct DIB networks of user-defined architectures. Our method does not require a complex optical setup, is versatile, contactless, benefits from both high spatial and temporal resolution, and could set a new paradigm for the assembly of smart, synthetic biosystems.
  • Conference paper
    Woodward RI, Murray RT, Phelan CF, de Oliveira REP, Li S, Eda G, de Matos CJSet al., 2016,

    Characterization of the Nonlinear Susceptibility of Monolayer MoS<inf>2</inf> using Second- and Third-Harmonic Generation Microscopy

    Second- and third-harmonic generation microscopy of monolayer MoS2 is reported for imaging and characterization of the material's nonlinearity. A telecommunication wavelength pump is used, revealing the material's promise for use in nonlinear optical devices.
  • Conference paper
    Zhai Z, Halder A, Wang Y, Núñez-Velázquez M, Sahu JKet al., 2016,

    Temperature Dependent Characteristics of L-band EDFA Using Phosphorus- and High Aluminum- Co-doped Silica Fibers

    We report a hybrid L-band amplifier employing phosphosilicate and high-aluminosilicate EDFs with 20.2±3.7dB gain and 4.2dB average NF from 1575-1615nm. The temperature-dependent-gain coefficient remains almost constant from 1585-1615nm over the temperature range -60 to +80°C.
  • Conference paper
    Murray RT, Runcorn TH, Kelleher EJR, Taylor JRet al., 2016,

    Multi-Watt-level 3.28-3.45 μm difference frequency generation using synchronous fiber lasers

    We report multi-Watt-level average power 3.28-3.45 μm difference frequency generation using two sychronous picosecond master oscillator power fiber amplifiers. Greater than 3.4 W of idler power is generated across the entire spectral tuning range.
  • Journal article
    Perdios L, Bunney TD, Warren SC, Dunsby C, French PM, Tate EW, Katan Met al., 2016,

    Time-resolved FRET reports FGFR1 dimerization and formation of a complex with its effector PLCγ1.

    , Advances in Biological Regulation, Vol: 60, Pages: 6-13, ISSN: 2212-4934

    In vitro and in vivo imaging of protein tyrosine kinase activity requires minimally invasive, molecularly precise optical probes to provide spatiotemporal mechanistic information of dimerization and complex formation with downstream effectors. We present here a construct with genetically encoded, site-specifically incorporated, bioorthogonal reporter that can be selectively labelled with exogenous fluorogenic probes to monitor the structure and function of fibroblast growth factor receptor (FGFR). GyrB.FGFR1KD.TC contains a coumermycin-induced artificial dimerizer (GyrB), FGFR1 kinase domain (KD) and a tetracysteine (TC) motif that enables fluorescent labelling with biarsenical dyes FlAsH-EDT2 and ReAsH-EDT2. We generated bimolecular system for time-resolved FRET (TR-FRET) studies, which pairs FlAsH-tagged GyrB.FGFR1KD.TC and N-terminal Src homology 2 (nSH2) domain of phospholipase Cγ (PLCγ), a downstream effector of FGFR1, fused to mTurquoise fluorescent protein (mTFP). We demonstrated phosphorylation-dependent TR-FRET readout of complex formation between mTFP.nSH2 and GyrB.FGFR1KD.TC. By further application of TR-FRET, we also demonstrated formation of the GyrB.FGFR1KD.TC homodimer by coumermycin-induced dimerization. Herein, we present a spectroscopic FRET approach to facilitate and propagate studies that would provide structural and functional insights for FGFR and other tyrosine kinases.
  • Conference paper
    Taylor JR, 2016,

    Fibre-integrated, non-linear manipulation of pulsed fibre lasers

    , Conference on Lasers and Electro-Optics (CLEO), Publisher: IEEE, ISSN: 2160-9020
  • Conference paper
    Murray RT, Kelleher EJR, Runcorn TH, Taylor JRet al., 2015,

    Multi-Watt-level 3.28-3.45 um difference frequency generation using synchronous fiber lasers

    , Mid-Infrared Coherent Sources 2016
  • Journal article
    Loiko PA, Arbabzadah EA, Damzen MJ, Mateos X, Dunina EB, Kornienko AA, Yasukevich AS, Skoptsov NA, Yumashev KVet al., 2015,

    Judd-Ofelt analysis and stimulated-emission cross-sections for highly doped (38 at%) Er:YSGG laser crystal

    , Journal of Luminescence, Vol: 171, Pages: 226-233, ISSN: 1872-7883

    Stimulated-emission cross-section spectra are determined for the ~1.5 μm and 3 μm transitions of Er3+ ions in YSGG crystal. For the 4I11/2→4I13/2 channel, the maximum stimulated-emission cross-section σSE is 0.43×10−20 cm2 at 2797.1 nm. For the 4I13/2→4I15/2 channel, σSE=1.20×10−20 cm2 at 1532.8 nm. Due to the reabsorption loss, laser operation is expected at ~1644 nm. Radiative lifetimes of all excited states of the Er3+ ion from 4I13/2 to 2H9/2 and probabilities of radiative transitions from these states are determined using the Judd–Ofelt theory. Radiative lifetimes of the 4I13/2 and 4I11/2 excited states for Er3+ ions in YSGG are 7.73 ms and 9.75 ms, respectively. Non-radiative decay is analyzed for lower excited-states of Er3+ ions in YSGG.
  • Journal article
    Gore DM, O'Brart DP, French P, Dunsby C, Allan BDet al., 2015,

    A Comparison of Different Corneal Iontophoresis Protocols for Promoting Transepithelial Riboflavin Penetration.

    , Investigative Ophthalmology & Visual Science, Vol: 56, Pages: 7908-7914, ISSN: 1552-5783

    PURPOSE: To measure corneal riboflavin penetration using different transepithelial iontophoresis protocols. METHODS: Freshly enucleated rabbit eyes were divided into nine treatment groups of 4 eyes. One group, in which 0.1% wt/vol riboflavin was applied for 30 minutes without iontophoresis after corneal epithelial debridement, acted as a control. The remaining groups were treated with an intact epithelium using different riboflavin formulations and varying iontophoresis current, soak, and rinse times. After riboflavin application, eyes were snap frozen in liquid nitrogen. Corneal cross sections 35 μm thick were then imaged immediately by two-photon fluorescence microscopy, using image processing software to quantify stromal riboflavin concentration at different corneal depths. RESULTS: In the epithelium-on iontophoresis treatment groups, greater stromal riboflavin penetration was achieved with higher-concentration riboflavin solutions, greater iontophoresis dosage, and longer solution contact times. A protocol utilizing 0.25% wt/vol riboflavin with benzalkonium chloride (BAC) 0.01% and two cycles of applied current and subsequent soaking (1 mA 5 minutes, soak 5 minutes; 0.5 mA 5 minutes, soak 5 minutes) achieved similar stromal riboflavin penetration to epithelium-off controls. The best-performing non-BAC-containing protocol produced stromal riboflavin penetration approximately 60% that of epithelium-off controls. Riboflavin solutions containing saline resulted in minimal stromal penetration. Riboflavin loading within the epithelium was equivalent to or higher than that in the subjacent stroma, despite rinsing the ocular surface with balanced salt solution. CONCLUSIONS: Modified iontophoresis protocols can significantly improve transepithelial riboflavin penetration in experimental corneal collagen cross-linking.
  • Journal article
    McCall MW, 2015,

    The Refractive Index of Electromagnetically Reciprocal Media

    , Journal of Optics, ISSN: 2040-8978

    We study the electromagnetics of media described by identical inhomogeneous relative dielectric and magnetic tensors, € = µ. Such media occur generically as spatial transformation media , i.e. electromagnetic media that are defined by a deformation of space. We show that such media are completely described by a refractive index n (r,ŝ) that depends on position r and directionŝ, but is independent of polarization. The phase surface is alwaysellipsoidal, and n (r,ŝ) is therefore represented by the radius vector to the surface of the ellipsoid. We apply our method to calculate the angular dependence of the refractive index in the well-studied cylindrical cloak and to a new kind of structurally chiral medium induced by a twist deformation. By way of a simple example we also show that media for which € = µ do notin general preserve the impedance properties of vacuum. The implications ofthis somewhat surprising conclusion for the field of transformation optics are discussed.
  • Journal article
    Roper JC, Yerolatsitis S, Birks TA, Mangan BJ, Dunsby C, French PMW, Knight JCet al., 2015,

    Minimizing Group Index Variations in a Multicore Endoscope Fiber

    , IEEE Photonics Technology Letters, Vol: 27, Pages: 2359-2362, ISSN: 1941-0174

    We describe a multicore fiber for nonlinear endoscopy where an ultrashort pulse is divided up and delivered through multiple cores to reduce the peak power. The variation in group index between cores of the fiber is minimized to allow simultaneously launched sub-pulses to arrive at the distal end of the fiber synchronously. Minimization of group index variation between cores is achieved at a V parameter of 3 owing to a turning point in the relationship between the group index and V parameter. For synchronized arrival times, single-mode propagation is important. By tapering a short length of the fiber at the launch end, the V value is locally brought below 2.405 allowing a pure fundamental mode to be launched into each core.
  • Journal article
    Kerridge-Johns WR, Damzen MJ, 2015,

    Analysis of pump excited state absorption and its impact on laser efficiency

    , Laser Physics Letters, Vol: 12, ISSN: 1612-202X

    Excited state absorption (ESA) is a process that occurs in many laser gain media and can significantly impact their efficiencies of operation. In this work we develop a model to quantify the effect of ESA at the pump wavelength on laser efficiency, threshold and heating. In an analysis based on the common end pumped laser geometry we derive solutions and analytical expressions that model the laser behaviour. From these solutions we discuss the main parameters affecting efficiency, such as the laser cavity loss, pump ESA cross section and stimulated emission cross section. Methodologies are described to minimise the impact of pump ESA, for example by minimising cavity loss. It is also shown that altering the pumping geometry can significantly improve performance by improved distribution of the population inversion. Double end pumping can approximately halve the effect of pump ESA compared to single end pumping, and side pumping also has the potential to arbitrarily reduce its effect.
  • Journal article
    Antonacci G, Pedrigi RM, Kondiboyina A, Mehta VV, de Silva R, Paterson C, Krams R, Toeroek Pet al., 2015,

    Quantification of plaque stiffness by Brillouin microscopy in experimental thin cap fibroatheroma

    , JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 12, ISSN: 1742-5689
  • Conference paper
    Thomas GM, Minassian A, Teppitaksak A, Damzen MJet al., 2015,

    High Energy Q-switching and Cavity Dumped Q-switching of a Diode-pumped Alexandrite Laser

    , Advanced Solid State Lasers
  • Conference paper
    Thomas GM, Damzen MJ, 2015,

    Next generation space and airborne laser technology - plenary‌

    , SpaceLab 2015
  • Conference paper
    Damzen MJ, Thomas GM, Teppitaksak A, Arbabzadah E, Kerridge-Johns W, Minassian Aet al., 2015,

    Diode-Pumped Alexandrite Laser—a new prospect for Remote Sensing

    , 11th Conference on Lasers and Electro-Optics/Pacific Rim, Publisher: IEEE

    Tunable-wavelength diode-pumped Alexandrite laser operation includes highest power > 26W (end-pumped rod); > 12W (side-pumped slab); and first Q-switched operation with pulse energy ~ 1mJ at kHz repetition rate, as development for space lidar application.
  • Journal article
    Correia T, Lockwood N, Kumar S, Yin J, Ramel M-C, Andrews N, Katan M, Bugeon L, Dallman MJ, McGinty J, Frankel P, French PMW, Arridge Set al., 2015,

    Accelerated optical projection tomography applied to in vivo imaging of zebrafish

    , PLOS One, Vol: 10, ISSN: 1932-6203

    Optical projection tomography (OPT) provides a non-invasive 3-D imaging modality that can be applied to longitudinal studies of live disease models, including in zebrafish. Current limitations include the requirement of a minimum number of angular projections for reconstruction of reasonable OPT images using filtered back projection (FBP), which is typically several hundred, leading to acquisition times of several minutes. It is highly desirable to decrease the number of required angular projections to decrease both the total acquisition time and the light dose to the sample. This is particularly important to enable longitudinal studies, which involve measurements of the same fish at different time points. In this work, we demonstrate that the use of an iterative algorithm to reconstruct sparsely sampled OPT data sets can provide useful 3-D images with 50 or fewer projections, thereby significantly decreasing the minimum acquisition time and light dose while maintaining image quality. A transgenic zebrafish embryo with fluorescent labelling of the vasculature was imaged to acquire densely sampled (800 projections) and under-sampled data sets of transmitted and fluorescence projection images. The under-sampled OPT data sets were reconstructed using an iterative total variation-based image reconstruction algorithm and compared against FBP reconstructions of the densely sampled data sets. To illustrate the potential for quantitative analysis following rapid OPT data acquisition, a Hessian-based method was applied to automatically segment the reconstructed images to select the vasculature network. Results showed that 3-D images of the zebrafish embryo and its vasculature of sufficient visual quality for quantitative analysis can be reconstructed using the iterative algorithm from only 32 projections—achieving up to 28 times improvement in imaging speed and leading to total acquisition times of a few seconds.
  • Journal article
    Antonacci G, Lepert G, Paterson C, Toeroek Pet al., 2015,

    Elastic suppression in Brillouin imaging by destructive interference

    , APPLIED PHYSICS LETTERS, Vol: 107, ISSN: 0003-6951
  • Journal article
    Ram IS, Kumar S, Singh RK, Singh P, Singh Ket al., 2015,

    Electrical conduction mechanism in Se<inf>90-x</inf>Te<inf>5</inf>Sn<inf>5</inf>In<inf>x</inf> (x = 0, 3, 6 and 9) multi-component glassy alloys

    , AIP Advances, Vol: 5

    Electrical conductivity of Se90-xTe5Sn5Inx (x = 0, 3, 6 and 9) glassy systems was studied employing impedance spectroscopic technique in the frequency range 100 Hz to 1 MHz and in the temperature range 308-388 K. The DC conductivity (σdc) at each temperature was evaluated from the low frequency plateau region for all the samples under investigation. The bulk conductivity for each sample was also evaluated from Nyquist impedance plots. The semicircle shape of Nyquist plot exhibit dipolar nature of samples. The activation energy for glassy, amorphous and crystalline region from the Arrhenius plot of the DC conductivity and bulk conductivity was evaluated. From the results it is found that activation energy varied from 0.091 to 0.194 eV in glassy, 0.686 to 0.002 eV in amorphous and 0.215 to 0.503 eV in crystalline region. The activation energy (ΔE) from DC conductivity and bulk conductivity found to be close in corresponding regions. The pre-exponential factor was also calculated for all three regions.
  • Conference paper
    Dyer BT, Elder JM, Lagarto J, Harding SE, French PMW, Peters NS, Dunsby C, Lyon ARet al., 2015,

    Application of label-free autofluorescence lifetime in vivo to measure changes in myocardial fibrosis and metabolism in a doxorubicin cardiomyopathy heart failure model

    , Congress of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 151-151, ISSN: 0195-668X
  • Journal article
    Woodward RI, Howe RCT, Runcorn TH, Hu G, Torrisi F, Kelleher EJR, Hasan Tet al., 2015,

    Wideband saturable absorption in few-layer molybdenum diselenide (MoSe₂) for Q-switching Yb-, Er- and Tm-doped fiber lasers.

    , Opt Express, Vol: 23, Pages: 20051-20061, ISSN: 1094-4087

    We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to Q-switch fiber lasers based on ytterbium (Yb), erbium (Er) and thulium (Tm) gain fiber, producing trains of microsecond-duration pulses with kilohertz repetition rates at 1060 nm, 1566 nm and 1924 nm, respectively. Such operating wavelengths correspond to sub-bandgap saturable absorption in MoSe2, which is explained in the context of edge-states, building upon studies of other semiconducting transition metal dichalcogenide (TMD)-based saturable absorbers. Our work adds few-layer MoSe2 to the growing catalog of TMDs with remarkable optical properties, which offer new opportunities for photonic devices.
  • Journal article
    Willison KR, Salehi-Reyhani A, Burgin E, Barclay M, Brown A, Neil MA, Ces O, Klug DRet al., 2015,

    Absolute quantification of protein copy number in single cells using single molecule microarrays

    , EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS, Vol: 44, Pages: S179-S179, ISSN: 0175-7571
  • Journal article
    Runcorn TH, Murray RT, Kelleher EJR, Popov SV, Taylor JRet al., 2015,

    Duration-tunable picosecond source at 560 nm with watt-level average power

    , Optics Letters, Vol: 40, Pages: 3085-3088, ISSN: 0146-9592

    A pulse source at 560 nm that is tunable in duration between 50 ps and 2.7 ns with >1  W of average power and near diffraction-limited beam quality is demonstrated. The source is based on efficient (up to 50%) second-harmonic generation in a periodically poled lithium tantalate crystal of a linearly polarized fiber-integrated Raman amplifier operating at 1120 nm. A duration-tunable ytterbium master-oscillator power-fiber amplifier is used to pulse-pump the Raman amplifier, which is seeded by a continuous-wave distributed-feedback laser diode at 1120 nm. The performance of the system using two different master oscillator schemes is compared. A pulse energy of up to 765 nJ is achieved with a conversion efficiency of 25% from the ytterbium fiber pump, demonstrating a compact and turn-key architecture for obtaining high peak-power radiation at 560 nm.
  • Journal article
    Gore DM, O'Brart D, French P, Dunsby C, Allan BDet al., 2015,

    Transepithelial Riboflavin Absorption in an Ex Vivo Rabbit Corneal Model

    , INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE, Vol: 56, Pages: 5006-5011, ISSN: 0146-0404
  • Journal article
    Warren SC, Margineanu A, Katan M, Dunsby C, French PMet al., 2015,

    Homo-FRET Based Biosensors and Their Application to Multiplexed Imaging of Signalling Events in Live Cells.

    , International Journal of Molecular Sciences, Vol: 16, Pages: 14695-14716, ISSN: 1661-6596

    Multiplexed imaging of Förster Resonance Energy Transfer (FRET)-based biosensors potentially presents a powerful approach to monitoring the spatio-temporal correlation of signalling pathways within a single live cell. Here, we discuss the potential of homo-FRET based biosensors to facilitate multiplexed imaging. We demonstrate that the homo-FRET between pleckstrin homology domains of Akt (Akt-PH) labelled with mCherry may be used to monitor 3'-phosphoinositide accumulation in live cells and show how global analysis of time resolved fluorescence anisotropy measurements can be used to quantify this accumulation. We further present multiplexed imaging readouts of calcium concentration, using fluorescence lifetime measurements of TN-L15-a CFP/YFP based hetero-FRET calcium biosensor-with 3'-phosphoinositide accumulation.
  • Conference paper
    Gore DM, O'Brart D, Dunsby C, Allan BDSet al., 2015,

    Transepithelial riboflavin absorption in an ex-vivo rabbit corneal model

    , Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO), Publisher: Association for Research in Vision and Ophthalmology, ISSN: 1552-5783
  • Conference paper
    Teppitaksak A, Thomas GM, Damzen MJ, 2015,

    Gain-switched diode laser seeding of ultra-high-gain Nd: YVO 4 bounce amplifier system as a versatile pulsed laser source

    , The European Conference on Lasers and Electro-Optics, Publisher: OSA Publishing
  • Conference paper
    Arbabzadah E, Kerridge-Johns W, Thomas GM, Minassian A, Damzen MJet al., 2015,

    High efficiency TEM00 diode end-pumped Alexandrite laser

    , The European Conference on Lasers and Electro-Optics
  • Conference paper
    Thomas GM, Minassian A, Damzen MJ, 2015,

    Directly diode-side-pumped Alexandrite slab lasers in the bounce geometry and optical vortex generation

    , The European Conference on Lasers and Electro-Optics

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://www.imperial.ac.uk:80/respub/WEB-INF/jsp/search-t4-html.jsp Request URI: /respub/WEB-INF/jsp/search-t4-html.jsp Query String: id=211&limit=30&resgrpMemberPubs=true&page=14&resgrpMemberPubs=true&respub-action=search.html Current Millis: 1722368377020 Current Time: Tue Jul 30 20:39:37 BST 2024