Physicshttps://hdl.handle.net/10468/2242024-03-29T10:35:49Z2024-03-29T10:35:49Z56013d absorption-spectra of Sr I through Sr IVMcGuinness, C.O'Sullivan, G.Carroll, P. K.Audley, D.Mansfield, Michael W. D.https://hdl.handle.net/10468/45642023-04-05T09:51:35Z1995-01-01T00:00:00Zdc.title: 3d absorption-spectra of Sr I through Sr IV
dc.contributor.author: McGuinness, C.; O'Sullivan, G.; Carroll, P. K.; Audley, D.; Mansfield, Michael W. D.
dc.description.abstract: The extreme ultraviolet photoabsorption spectra of neutral to three-times-ionized strontium have been recorded in a comprehensive series of experiments with the dual laser-produced plasma technique. Striking differences were found in the spectra, which can be attributed to the transfer of oscillator strength from 3d→np to 3d→nf transitions at Sr2+ due to nf wave-function contraction. In Sr and Sr+, 3d→5p transitions dominate; in Sr2+, 3d→nf transitions are most intense, while in Sr3+ the 4p subshell opens and 3d→4p transitions are the strongest features. Partial cross sections for 3d→ɛf and 3d→ɛp photoionization were calculated and compared with experiment.
1995-01-01T00:00:00Z42.6 Gbit/s fully integrated all-optical XOR gateDailey, James M.Ibrahim, Selwan K.Manning, Robert J.Webb, Rod P.Lardenois, SébastienMaxwell, Graeme D.Poustie, Alistair J.https://hdl.handle.net/10468/4122023-04-04T09:07:54Z2009-09-01T00:00:00Zdc.title: 42.6 Gbit/s fully integrated all-optical XOR gate
dc.contributor.author: Dailey, James M.; Ibrahim, Selwan K.; Manning, Robert J.; Webb, Rod P.; Lardenois, Sébastien; Maxwell, Graeme D.; Poustie, Alistair J.
dc.description.abstract: We demonstrate an SOA-based all-optical high-speed Mach-Zehnder interferometer exclusive- OR (XOR) gate fabricated in a silica III-V hybrid-integration technology platform. The device includes integrated time delays for rapid differential operation as well as integrated phase shifters for fine tuning of power splitters and interferometer bias enabling highly optimized XOR gate operation. XOR functionality is verified through inspection of the output pulse sequence and the carrier-suppressed output spectrum. A 2.3 dB penalty for a 42.6 Gb/s RZ-OOK signal at a 10-9 bit error rate is observed.
2009-09-01T00:00:00ZA black widow population dissection through HiPERCAM multiband light-curve modellingMata Sánchez, D.Kennedy, Mark R.Clark, C. J.Breton, R. P.Dhillon, V. S.Voisin, G.Camilo, F.Littlefair, S.Marsh, T. R.https://hdl.handle.net/10468/152212023-11-11T02:02:17Z2023-01-19T00:00:00Zdc.title: A black widow population dissection through HiPERCAM multiband light-curve modelling
dc.contributor.author: Mata Sánchez, D.; Kennedy, Mark R.; Clark, C. J.; Breton, R. P.; Dhillon, V. S.; Voisin, G.; Camilo, F.; Littlefair, S.; Marsh, T. R.
dc.description.abstract: Black widows are extreme millisecond pulsar binaries where the pulsar wind ablates their low-mass companion stars. In the optical range, their light curves vary periodically due to the high irradiation and tidal distortion of the companion, which allows us to infer the binary parameters. We present simultaneous multiband observations obtained with the HIPERCAM instrument at the 10.4-m GTC telescope for six of these systems. The combination of this five-band (us, gs,rs, is, zs) fast photometer with the world’s largest optical telescope enables us to inspect the light curve range near minima. We present the first light curve for PSR J1641+8049, as well as attain a significant increase in signal to noise and cadence compared with previous publications for the remaining five targets: PSR J0023+0923, PSR J0251+2606, PSR J0636+5129, PSR J0952−0607, and PSR J1544+4937. We report on the results of the light-curve modelling with the ICARUS code for all six systems, which reveals some of the hottest and densest companion stars known. We compare the parameters derived with the limited but steadily growing black widow population for which optical modelling is available. We find some expected correlations, such as that between the companion star mean density and the orbital period of the system, which can be attributed to the high number of Roche-lobe filling companions. On the other hand, the positive correlation between the orbital inclination and the irradiation temperature of the companion is puzzling. We propose such a correlation would arise if pulsars with magnetic axis orthogonal to their spin axis are capable of irradiating their companions to a higher degre
2023-01-19T00:00:00ZA comparison between off and on-chip injection locking in a photonic integrated circuitPerrott, Alison H.Caro, LudovicDernaika, MohamadPeters, Frank H.https://hdl.handle.net/10468/88742023-04-04T09:02:42Z2019-10-01T00:00:00Zdc.title: A comparison between off and on-chip injection locking in a photonic integrated circuit
dc.contributor.author: Perrott, Alison H.; Caro, Ludovic; Dernaika, Mohamad; Peters, Frank H.
dc.description.abstract: The mutual and injection locking characteristics of two integrated lasers are compared, both on and off-chip. In this study, two integrated single facet slotted Fabry–Pérot lasers are utilised to develop the measurement technique used to examine the different operational regimes arising from optically locking a semiconductor diode laser. The technique employed used an optical spectrum analyser (OSA), an electrical spectrum analyser (ESA) and a high speed oscilloscope (HSO). The wavelengths of the lasers are measured on the OSA and the selected optical mode for locking is identified. The region of injection locking and various other regions of dynamical behaviour between the lasers are observed on the ESA. The time trace information of the system is obtained from the HSO and performing the FFT (Fast Fourier Transform) of the time traces returns the power spectra. Using these tools, the similarities and differences between off-chip injection locking with an isolator, and on-chip mutual locking are examined.
2019-10-01T00:00:00ZA comparison between radio loud and quiet gamma-ray bursts, and evidence for a potential correlation between intrinsic duration and redshift in the radio loud populationLloyd-Ronning, Nicole M.Gompertz, BenPe'er, AsafDainotti, M. G.Fruchter, Andrew S.https://hdl.handle.net/10468/75002023-04-05T09:53:24Z2019-01-25T00:00:00Zdc.title: A comparison between radio loud and quiet gamma-ray bursts, and evidence for a potential correlation between intrinsic duration and redshift in the radio loud population
dc.contributor.author: Lloyd-Ronning, Nicole M.; Gompertz, Ben; Pe'er, Asaf; Dainotti, M. G.; Fruchter, Andrew S.
dc.description.abstract: We extend our study of energetic radio-loud and -quiet gamma-ray bursts (GRBs), suggesting these GRBs potentially come from two separate progenitor systems. We expand the sample from our previous paper and find that our results are strengthened—radio-quiet GRBs have significantly shorter intrinsic prompt duration, and are also less energetic on average. However, the tenuous correlation between isotropic energy and intrinsic duration in the radio dark sample remains tenuous and is slightly weakened by adding more bursts. Interestingly, we find an anticorrelation between the intrinsic duration and redshift in the radio bright sample but not the radio dark sample, further supporting that these two samples may come from separate progenitors. We also find that very high energy (0.1–100 GeV) extended emission is only present in the radio-loud sample. There is no significant difference between the presence of X-ray/optical plateaus or the average jet opening angles between the two samples. We explore the interpretation of these results in the context of different progenitor models. The data are consistent with the radio-loud GRBs coming from a helium merger system and the radio-quiet GRBs coming from a collapsar system, but may also reflect other dichotomies in the inner engine such as a neutron star versus black hole core.
2019-01-25T00:00:00ZA comprehensive K 2 and ground-based study of CRTS J035905.9+175034, an eclipsing SU UMa system with a large mass ratioLittlefield, ColinGarnavich, Peter M.Kennedy, Mark R.Szkody, PaulaZhibin, Daihttps://hdl.handle.net/10468/66422023-04-05T09:52:41Z2018-05-14T00:00:00Zdc.title: A comprehensive K 2 and ground-based study of CRTS J035905.9+175034, an eclipsing SU UMa system with a large mass ratio
dc.contributor.author: Littlefield, Colin; Garnavich, Peter M.; Kennedy, Mark R.; Szkody, Paula; Zhibin, Dai
dc.description.abstract: CRTS J035905.9+175034 is the first eclipsing SU UMa system for which a superoutburst has been observed by Kepler in the short-cadence mode. The light curve contains one superoutburst, eight normal outbursts (including a precursor to the superoutburst), and several minioutbursts that are present before—but not after—the superoutburst. The superoutburst began with a precursor normal outburst, and shortly after the peak of the precursor, the system developed large-amplitude superhumps that achieved their maximum amplitude after just three superhump cycles. The period excess of the initial superhump period relative to the orbital period implies a mass ratio of 0.281 ± 0.015, placing it marginally above most theoretical predictions of the highest-possible mass ratio for superhump formation. In addition, our analysis of the variations in eclipse width and depth, as well as the hot spot amplitudes, generally provides substantiation of the thermal-tidal instability model. The K 2 data, in conjunction with our ground-based time-resolved spectroscopy and photometry from 2014 to 2016, allows us to determine many of the fundamental parameters of this system.
2018-05-14T00:00:00ZA concertina-shaped vibration energy harvester-assisted NFC sensor with improved wireless communication rangePaul, KankanaGawade, Dinesh R.Simorangkir, Roy B. V. B.O'Flynn, BrendanBuckley, John L.Amann, AndreasRoy, Saibalhttps://hdl.handle.net/10468/135392023-04-04T09:11:24Z2022-01-01T00:00:00Zdc.title: A concertina-shaped vibration energy harvester-assisted NFC sensor with improved wireless communication range
dc.contributor.author: Paul, Kankana; Gawade, Dinesh R.; Simorangkir, Roy B. V. B.; O'Flynn, Brendan; Buckley, John L.; Amann, Andreas; Roy, Saibal
dc.description.abstract: The explosive growth of wireless sensor platforms and their emerging wide range of application areas make the development of a sustainable and robust power source, an essential requirement to enable widespread deployment of these wireless devices. As a solution to this cardinal issue, this paper reports the design and fabrication of a resonant Vibration Energy Harvester (VEH) that comprises interleaved springs, manifesting a concertina shaped structure that can enable large mechanical amplitudes of oscillation. Within a relatively small footprint (9cm3), this concertina-VEH yields a large power density of 455.6μW/cm3g2 while operating at a resonant frequency of 75Hz. Additionally, the feasibility of the implemented VEH to support NFC based wireless sensor platform, that is yet uncharted, is also investigated in this work. A very low-power consumption Near Field Communication (NFC) wireless sensor node has been designed and developed for this purpose. The developed concertina VEH has been employed to power the electronics interface of this NFC sensor. Using mechanical energy derived from as low as 0.2g excitation, our study shows that the VEH can enhance the electromagnetic interaction between the transmitting antenna and the reader, resulting in a 120% increase in wireless communication range for the NFC sensor node. Such a high-performance energy harvester assisted NFC sensor node has the potential to be used in a wide range of Internet of Things (IoT) platforms as a reliable and sustainable power solution.
2022-01-01T00:00:00ZA facetless regrowth-free single mode laser based on MMI couplersCaro, LudovicKelly, Niall P.Dernaika, MohamadShayesteh, MaryamMorrissey, Padraic E.Alexander, Justin K.Peters, Frank H.https://hdl.handle.net/10468/39182023-04-04T09:06:01Z2017-04-20T00:00:00Zdc.title: A facetless regrowth-free single mode laser based on MMI couplers
dc.contributor.author: Caro, Ludovic; Kelly, Niall P.; Dernaika, Mohamad; Shayesteh, Maryam; Morrissey, Padraic E.; Alexander, Justin K.; Peters, Frank H.
dc.description.abstract: This paper presents a facetless, tunable laser operating near 1575 nm, as well as a theoretical model predicting spectral features of the laser. The lasers were fabricated without regrowth or advanced lithography techniques, and are based on MMI couplers and etched facets. Coarse vernier tuning was achieved over a range of 25 nm, while fine, thermal tuning was also demonstrated over a range of 1.5 nm. SMSR values of 25 dB and higher were observed, with a measured laser linewidth of 600 kHz.
2017-04-20T00:00:00ZA heat-and-pull rig for fiber taper fabricationWard, Jonathan M.O'Shea, Danny G.Shortt, Brian J.Morrissey, Michael J.Deasy, KieranNic Chormaic, Sílehttps://hdl.handle.net/10468/2362023-04-04T09:15:58Z2006-08-01T00:00:00Zdc.title: A heat-and-pull rig for fiber taper fabrication
dc.contributor.author: Ward, Jonathan M.; O'Shea, Danny G.; Shortt, Brian J.; Morrissey, Michael J.; Deasy, Kieran; Nic Chormaic, Síle
dc.description.abstract: We describe a reproducible method of fabricating adiabatic tapers with 3–4 μm diameter. The method is based on a heat-and-pull rig, whereby a CO2 laser is continuously scanned across a length of fiber that is being pulled synchronously. Our system relies on a CO2 mirror mounted on a geared stepper motor in order to scan the laser beam across the taper region. We show that this system offers a reliable alternative to more traditional rigs incorporating galvanometer scanners. We have routinely obtained transmission losses between 0.1 and 0.3 dB indicating the satisfactory production of adiabatic tapers. The operation of the rig is described in detail and an analysis on the produced tapers is provided. The flexibility of the rig is demonstrated by fabricating prolate dielectric microresonators using a microtapering technique. Such a rig is of interest to a range of fields that require tapered fiber fabrication such as microcavity-taper coupling, atom guiding along a tapered fiber, optical fiber sensing, and the fabrication of fused biconical tapered couplers.
2006-08-01T00:00:00ZA high-speed vertical transition for multi-layer A1N carrier boards designed by time-domain reflectometryJezzini, Moises A.Marraccini, Philip J.Peters, Frank H.https://hdl.handle.net/10468/98732023-04-05T09:47:51Z2019-06-01T00:00:00Zdc.title: A high-speed vertical transition for multi-layer A1N carrier boards designed by time-domain reflectometry
dc.contributor.author: Jezzini, Moises A.; Marraccini, Philip J.; Peters, Frank H.
dc.description.abstract: High density, high speed photonic integrated circuits (PICs) have large numbers of closely spaced DC and RF contacts, which must be connected in the package. The use of multilayer carrier boards to interface between the contacts and the package gives high performance and high density. In order to be effective as a packaging solution, these multi-layer carrier boards need high-speed electrical channels with good performance. Also, the boards usually need high thermal conductivity to manage the heat. Co-fired aluminium nitride (A1N) has the needed high thermal conductivity. However, there are no designs of multi-layer high-speed channels in the literature for co-fired A1N. Therefore, this article presents a high-speed multi-layer channel for co-fired A1N and its measured results. Two transmission lines were designed that showed a measured loss of Ë 0.09dBmm-1 at 40GHz. The vertical transition allows for arbitrary planar rotations of the channel and showed a measured 3 dB bandwidth of 33 GHz and small penalties in the eye diagram with a 44 Gbits-1 signal. The channels showed crosstalk below -30 dB.
2019-06-01T00:00:00Z