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Displaying Results 126 - 150 of 170 on page 6 of 7
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Photopatternable ionogels for electrochromic applications
(2011)
Kavanagh, Andrew; Copperwhite, Robert; Oubaha, Mohamed; Owens, Jessica; McDonagh, Colet...
Photopatternable ionogels for electrochromic applications
(2011)
Kavanagh, Andrew; Copperwhite, Robert; Oubaha, Mohamed; Owens, Jessica; McDonagh, Colette; Diamond, Dermot; Byrne, Robert
Abstract:
This work describes the development of photopatternable ionogels based on a hybrid organic/inorganic sol–gel material and both phosphonium (trihexyltetradecylphosphonium dicyanamide [P6,6,6,14][dca], trihexyltetradecylphosphonium bis(trifluoromethanesulfonyl)-amide [P6,6,6,14][NTf2]) and imidazolium (1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate [emIm][FAP]) room temperature ionic liquids (RTILs). Ionogels were prepared via a two step process with the RTIL content varied between 40 and 80 w/w%, and characterised via Raman and Electrochemical Impedance Spectroscopy. 1 and 2 photon polymerisation was performed on the hybrid ionogels using photolithography, resulting in three dimensional structures that were characterised using scanning electron microscopy. Electrochromic ionogels were prepared by addition of ethyl viologen dibromide (EV) to an ionogel containing [emIm][FAP] and hybrid sol–gel material. This composition was photopolymerised on ITO electrodes by ...
http://doras.dcu.ie/16364/
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Polarization dependence of non-linear gain compression factor in semiconductor optical amplifier
(2008)
Philippe, Severine; Bradley, Ann Louise; Maldonado-Basilio, Ramón; Surre, Frederic; Ken...
Polarization dependence of non-linear gain compression factor in semiconductor optical amplifier
(2008)
Philippe, Severine; Bradley, Ann Louise; Maldonado-Basilio, Ramón; Surre, Frederic; Kennedy, Brendan F.; Landais, Pascal; Soto-Ortiz, Horacio
Abstract:
We investigate the power and the polarization dependence of the intraband dynamics in a bulk semiconductor optical amplifier using both a 2.5-ps pump-probe experimental set-up in contra-propagation and a theoretical model. Our model is based on the rate equations and takes into account the polarization dependence of the gain. By comparing experimental and computational results we are able to highlight the dependences of the intraband dynamics and to extract the non-linear gain compression factor as a function of both pulse energy and polarization of the injected pulses
http://doras.dcu.ie/24772/
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Portable integrated micro-fluidic platform for the monitoring and detection of nitrite
(2013)
Czugala, Monika; Fay, Cormac; O'Connor, Noel E.; Corcoran, Brian; Benito-Lopez, Fe...
Portable integrated micro-fluidic platform for the monitoring and detection of nitrite
(2013)
Czugala, Monika; Fay, Cormac; O'Connor, Noel E.; Corcoran, Brian; Benito-Lopez, Fernando; Diamond, Dermot
Abstract:
A wireless, portable integrated micro-fluidic platform is proposed and applied for the determination of nitrite anions in water. The colourimetric analysis of nitrite is based on the Griess reagent, and the colour intensity of nitrite Griess reagent complex is detected using a low cost Paired Emitter Detector Diode technique. The micro-fluidic device employed a photoswitchable micro-valve, controlled by white light and generated using a light emitting diode. This low-cost and low-power detector exhibited very low limits of detection (34 ± 0.1 μg L-1). Freshwater samples were analysed and the results were compared to those generated with a conventional UV-Vis spectrophotometer showing good agreement. The suitability of the analyser for the precise and continuous measurement of samples was established. In addition, its small size and low weight offered the advantage of portability, while its data logging capabilities allowed for independent nitrite monitoring. Moreover, integration of...
http://doras.dcu.ie/20389/
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Precursor concentration and substrate effects on high rate dip-coated vanadium oxide thin films.
(2015)
Glynn, Colm; Aureau, Damien; O'Hanlon, Sally; Daly, Luke; Geaney, Hugh; Collins, G...
Precursor concentration and substrate effects on high rate dip-coated vanadium oxide thin films.
(2015)
Glynn, Colm; Aureau, Damien; O'Hanlon, Sally; Daly, Luke; Geaney, Hugh; Collins, Gillian; Etcheberry, Arnaud; O'Dwyer, Colm
Abstract:
Uniform thin films of vanadium pentoxide were dip-coated from a high-concentration vanadium oxytriisopropoxide precursor which is shown to be resistant to the dewetting processes which can form surface pinhole defects. Through appropriate withdrawal speed choice, the thin films have a smooth uniform surface morphology with a low rms roughness of <1 nm in both their amorphous and crystallized states. The structure of the thin films follows that of bulk vanadium pentoxide but in a nanostructured form. The deposition methods shown can be applied to prepare thin films upon a variety of different substrates and other alkoxide based metal oxide materials.
http://hdl.handle.net/10468/6284
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Pulsed laser deposition and characterisation of ZnO and aluminium-doped ZnO nanostructures on silicon and flexible plastic substrates
(2016)
Inguva, Saikumar
Pulsed laser deposition and characterisation of ZnO and aluminium-doped ZnO nanostructures on silicon and flexible plastic substrates
(2016)
Inguva, Saikumar
Abstract:
We have developed recipes for the catalyst-free growth of upstanding/vertically aligned ZnO nanorods featuring core/shell or interconnected core/shell architectures on ZnO-seeded Si (100) substrates using the pulsed laser deposition (PLD) technique. The structural, morphological and luminescent properties of these ZnO nanorod samples were established. A ZnO emission band at 3.331 eV was observed in the core/shell and interconnected core/shell nanorod architectures and its origin linked to the defects observed at the crystalline/amorphous interface of the core/shell structure. This particular defect PL emission appears to be a new observation for ZnO. We have grown vertically aligned ZnO nanorods on PLD prepared ZnO-seeded Si substrates by catalyst-free vapour phase transport (VPT). The nanorods featured excellent optical properties and a coverage density higher than previously published data. The structural, morphological and luminescent properties of the seed layers and nanorods we...
http://doras.dcu.ie/21004/
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Pulsed laser deposition of plasmonic nanostructured gold on flexible transparent polymer at atmospheric pressure
(2017)
McCann, Ronán; Hughes, Cian; Bagga, Komal; Stalcup, Apryll; Vázquez, Mercedes; Brabazon...
Pulsed laser deposition of plasmonic nanostructured gold on flexible transparent polymer at atmospheric pressure
(2017)
McCann, Ronán; Hughes, Cian; Bagga, Komal; Stalcup, Apryll; Vázquez, Mercedes; Brabazon, Dermot
Abstract:
In this paper, we outline a novel technique for the deposition of nanostructured thin films utilizing a modified form of pulsed laser deposition (PLD). We demonstrate Confined Atmospheric PLD (CAP) for the deposition of gold on cyclic olefin polymer substrates. The deposition process is a simplified form of conventional PLD, with deposition conducted under atmospheric conditions and the substrate and target in close proximity. It was found that this confinement results in the deposition of nanostructured thin films on the substrate. Infrared spectroscopy showed no significant change of polymer surface chemistry as a result of the deposition process, and optical spectroscopy revealed plasmonic behavior of the resulting thin film. The effect of laser fluence on the deposition process was also examined with more uniform films deposited at higher fluences.
http://doras.dcu.ie/21828/
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Quantum dash mode-locked laser based open-loop optical clock recovery for 160 Gb/s transmission system
(2013)
Luo, Jun; Parra-Cetina, Josué; Maldonado-Basilio, Ramón; Landais, Pascal; Dorren, Harme...
Quantum dash mode-locked laser based open-loop optical clock recovery for 160 Gb/s transmission system
(2013)
Luo, Jun; Parra-Cetina, Josué; Maldonado-Basilio, Ramón; Landais, Pascal; Dorren, Harmen J.S.; Calabretta, Nicola
Abstract:
We report first demonstration of quantum dash mode-locked laser based open-loop optical clock recovery of 160 Gb/s RZ-OOK after 52 km transmission with 102 fs timing jitter 40 GHz clock and 2 dB BER penalty
http://doras.dcu.ie/24894/
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Radiation-hard silicon photonics for future high energy physics experiments
(2017)
Zeiler, Marcel
Radiation-hard silicon photonics for future high energy physics experiments
(2017)
Zeiler, Marcel
Abstract:
Collisions of proton beams in the Large Hadron Collider at CERN produce very high radiation levels in the innermost parts of the particle detectors and enormous amounts of measurement data. Thousands of radiation-hard optical links based on directly-modulated laser diodes are thus installed in the particle detectors to transmit the measurement data to the processing electronics. The radiation levels in the innermost regions of future particle detectors will be much higher than they are now. Alternative solutions to laser-based radiation-hard optical links have to be found since the performance of laser diodes decreases beyond the operation margin of the system when irradiated to sufficiently high radiation levels. Silicon Photonics (SiPh) is currently being investigated as a promising alternative technology. First tests have indeed shown that SiPh Mach-Zehnder modulators (MZMs) are relatively insensitive to a high neutron fluence. However, they showed a strong degradation when expos...
http://doras.dcu.ie/21848/
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Radio frequency and terahertz signals generated by passively mode-locked semiconductor lasers
(2010)
Latkowski, Sylwester
Radio frequency and terahertz signals generated by passively mode-locked semiconductor lasers
(2010)
Latkowski, Sylwester
Abstract:
There are several different approaches to generating periodic signals using semiconductor lasers, for example: Q-switching, gain switching or mode-locking schemes. In general the active or passive mode-locking techniques require the use of a modulator or a saturable absorber in order to achieve the phase synchronisation. The laser diodes studied in this thesis, are demonstrated to operate in the mode-locked regime, while not requiring any direct or external modulation, nor the saturable absorbtion element in order to achieve the phase synchronisation. It has been demonstrated previously, that in a multimode semiconductor laser, the third order nonlinearities of a gain medium resulting in the four-wave-mixing effects, are responsible for the phase synchronisation and lead to phase locking. The repetition rate of the generated signal is fixed by the free-spectral range of the longitudinal spectrum. Therefore, with a passively mode-locked laser (PMLL) it is possible to cover a wide ran...
http://doras.dcu.ie/16001/
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Radio over fibre distribution systems for ultra-wide band and millimetre wave applications
(2011)
Shams Eldin, Haymen
Radio over fibre distribution systems for ultra-wide band and millimetre wave applications
(2011)
Shams Eldin, Haymen
Abstract:
Short range wireless technology such as ultra-wideband (UWB) and 60 GHz millimetre wave (mm-wave) play a key role for wireless connectivity in indoor home, office environment or large enclosed public areas. UWB has been allocated at the frequency band 3.1-10.6 GHz with an emission power below -41.3 dBm. Mm-wave signals around 60 GHz have also attracted much attention to support high-speed data for short range wireless applications. The wide bandwidth and high allowable transmit power at 60 GHz enable multi-Gbps wireless transmission over typical indoor distances. Radio-over-fibre (RoF) systems are used to extend the propagation distance of both UWB and mm-wave signals over hundred of meters inside a building. UWB or mm-wave signals over fibre can be generated first at the central office before being distributed to the remote access points through optical fibre. In this work, we investigate two new techniques to generate and distribute UWB signals. These techniques are based on gene...
http://doras.dcu.ie/16295/
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Short pulse generation with 40 GHz passively-mode locked Q-dashed Fabry-Perot laser
(2009)
Latkowski, Sylwester; Maldonado-Basilio, Ramón; Landais, Pascal
Short pulse generation with 40 GHz passively-mode locked Q-dashed Fabry-Perot laser
(2009)
Latkowski, Sylwester; Maldonado-Basilio, Ramón; Landais, Pascal
Abstract:
Generation of sub-picosecond pulses by a dc-biased passively mode-locked Fabry-Pérot laser is demonstrated. By using a tunable band-pass filter, it is observed that the width of the generated pulses decreases in direct proportion to the optical modes emitted by the laser. Furthermore, performing a passive compression by a piece of single mode fiber, we demonstrate the generation of 720 fs pulses by this type of mode-locked Fabry-Pérot laser.
http://doras.dcu.ie/24853/
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Silicon photonic 2.5D integrated multi-chip module receiver
(2020)
Abrams, Nathan C.; Cheng, Qixiang; Glick, Madeleine; Jezzini, Moises; Morrissey, Padrai...
Silicon photonic 2.5D integrated multi-chip module receiver
(2020)
Abrams, Nathan C.; Cheng, Qixiang; Glick, Madeleine; Jezzini, Moises; Morrissey, Padraic; O'Brien, Peter; Bergman, Keren
Abstract:
We demonstrate the first 2.5D integrated, wavelength division multiplexing, silicon photonic receiver. The multi-chip module utilizes a silicon interposer to integrate the four-channel photonic cascaded microdisk receiver with four electronic transimpedance amplifiers.
http://hdl.handle.net/10468/10658
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Silicon-photonics-based wideband radar beamforming: basic design
(2010)
Fathpour, Sasan; Riza, Nabeel A.
Silicon-photonics-based wideband radar beamforming: basic design
(2010)
Fathpour, Sasan; Riza, Nabeel A.
Abstract:
Proposed is silicon-photonics-based phased array antenna beamforming for high-resolution long-range radars with wide instantaneous radio frequency (rf) bandwidth. Specifically, the proposed silicon-photonics beamformer platform offers the potential for cost-effective monolithic chip-scale integration of photonic delay lines, 2×2 optical switches, variable optical attenuators, and optical amplifiers that form the base unit of a rf transmit/receive array signal processor. In effect, the proposed silicon-photonics devices empower the design of a powerful proposed photonic beamformer with one time-delay unit per antenna element. Device-level designs studies are shown that promise meeting the high-resolution radar mission-critical requirements via time delays of up to 2.5 ns, switching times of less than 100 ns, optical isolations as good as 50 dB, and optical gains of up to 6 dB. Longer delays are achieved off chip using optical fibers.
http://hdl.handle.net/10468/10138
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Single-shot characterization of independent femtosecond extreme ultraviolet free electron and infrared laser pulses
(2007)
Dardis, John; Kavanagh, Kevin D.; Pedregosa-Gutierrez, Jofre; Yeates, Patrick; Kennedy,...
Single-shot characterization of independent femtosecond extreme ultraviolet free electron and infrared laser pulses
(2007)
Dardis, John; Kavanagh, Kevin D.; Pedregosa-Gutierrez, Jofre; Yeates, Patrick; Kennedy, Eugene T.; Costello, John T.
Abstract:
Two-color above threshold ionization of helium and xenon has been used to analyze the synchronization between individual pulses of the femtosecond extreme ultraviolet (XUV) Free electron LASer in Hamburg and an independent intense 120 fs mode-locked Ti:Sa laser. Characteristic sidebands appear in the photoelectron spectra when the two pulses overlap spatially and temporally. The cross-correlation curve points to a 250 fs r.m.s. jitter between the two sources at the experiment. A more precise determination of the temporal fluctuation between the XUV and infrared pulses is obtained through the analysis of the single-shot sideband intensities.
http://doras.dcu.ie/74/
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Smart optical imaging systems with automated electronics
(2017)
La Torre, Juan Pablo
Smart optical imaging systems with automated electronics
(2017)
La Torre, Juan Pablo
Abstract:
In this dissertation, proposed and demonstrated are several novel smart electronically automated optical designs to efficiently solve existing real-world problems in the field of shape sensing and imaging. First half of the thesis proposes shape sensing techniques that use an Electronically Controlled Variable Focus Lens (ECVFL) within a smart optical design suitable for a wide range of applications including shape sensing and projection displays. The second part of this dissertation involves the use of the Digital Micromirror Device (DMD) deployed within several smart optical designs including an embedded laser beam profiler and a new camera idea which is inspired by the Telecommunication science field. Specifically, proposed and demonstrated is the design and implementation of the novel imaging device called Coded Access Optical Sensor (CAOS) where CAOS is able of operating with different application dependent working modes. Experimentally and successfully demonstrated for the fir...
http://hdl.handle.net/10468/5746
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Solution processable metal oxide thin film deposition and material growth for electronic and photonic devices
(2016)
Glynn, Colm; O'Dwyer, Colm
Solution processable metal oxide thin film deposition and material growth for electronic and photonic devices
(2016)
Glynn, Colm; O'Dwyer, Colm
Abstract:
A comprehensive review of recent advances in solution processing and growth of metal-oxide thin films for electronic and photonic devices is presented, with specific focus on precise solution-based technological coatings for electronics and optics, and new concepts for oxide material growth for electrochemical, catalytic, energy storage and conversion systems, information technology, semiconductor device processing and related devices. Throughout, the nature of the soluble precursors solutions and their relationship to film formation process by various solution coating techniques are collated and compared, highlighting advantages in precursor design for creating complex oxides for devices. Because of the versatility of solution-processable oxides and functional material coating, it is important to capture the advances made in oxide deposition for plastic electronics, see-through and wearable devices, and high-fidelity thin film transistors on curved or flexible displays. Solution pr...
http://hdl.handle.net/10468/6046
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Spatial frequency domain correlation mapping optical coherence tomography for nanoscale structural characterization
(2019)
Alexandrov, Sergey; McNamara, Paul M.; Das, Nandan; Zhou, Yi; Lynch, Gillian; Hogan, Jo...
Spatial frequency domain correlation mapping optical coherence tomography for nanoscale structural characterization
(2019)
Alexandrov, Sergey; McNamara, Paul M.; Das, Nandan; Zhou, Yi; Lynch, Gillian; Hogan, Josh; Leahy, Martin
Abstract:
Most of the fundamental pathological processes in living tissues exhibit changes at the nanoscale. Noninvasive, label-free detection of structural changes in biological samples pose a significant challenge to both researchers and healthcare professionals. It is highly desirable to be able to resolve these structural changes, during physiological processes, both spatially and temporally. Modern nanoscopy largely requires labeling, is limited to superficial 2D imaging, and is generally not suitable for in vivo applications. Furthermore, it is becoming increasingly evident that 2D biology often does not translate into the real 3D situation. Here, we present a method, spatial frequency domain correlation mapping optical coherence tomography (sf-cmOCT), for detection of depth resolved nanoscale structural changes noninvasively. Our approach is based on detection and correlation of the depth resolved spectra of axial spatial frequencies of the object which are extremely sensitive to struc...
http://hdl.handle.net/10379/15457
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Spectrally efficient modulation formats for fast reconfigurable optical networks
(2014)
Huynh, Tam
Spectrally efficient modulation formats for fast reconfigurable optical networks
(2014)
Huynh, Tam
Abstract:
The desire for multi-media content and richly interactive data services is shaping a new era for telecommunications networks. Future networks will need to be capable of offering Triple Play, IPTV, Video-on-Demand, Voice-over-IP and High-Speed Internet Access, combined with guaranteed Quality of Service. These networks will employ optical transport networks with wavelength division multiplexing (WDM) technology, and advanced modulation formats, in order to achieve the high capacities required. In addition, given the bursty nature of this data it is expected that dynamic allocation of the bandwidth will be implemented to efficiently use the available capacity. The key component in these networks will be the tuneable laser transmitters that generate the different wavelength packets. This thesis has explored novel applications and implementations of the sample-grating distributed Bragg reflector (SG-DBR) lasers, in optical WDM networks. Through theory, simulations and experiments, the u...
http://doras.dcu.ie/19977/
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Study of exciton-polariton modes in nanocrystalline thin films of CuCl using reflectance spectroscopy
(2012)
Foy, Barry; McGlynn, Enda; Cowley, Aidan; McNally, Patrick J.; Henry, Martin O.
Study of exciton-polariton modes in nanocrystalline thin films of CuCl using reflectance spectroscopy
(2012)
Foy, Barry; McGlynn, Enda; Cowley, Aidan; McNally, Patrick J.; Henry, Martin O.
Abstract:
CuCl thin films grown on (100) Si by thermal evaporation are studied using reflectance spectroscopy. The reflectance spectra in the near UV spectral range close to the CuCl bandgap are modeled using a dielectric response function based on an exciton-polariton response with various models involving dead layers and reflected waves in the thin film. The exciton-polariton structure obtained is compared to other studies of bulk CuCl crystals. These different models are analyzed using a matrix-based approach and they yield theoretical spectra of reflected intensity. The fits provide parameter values which can be compared to bulk data known for CuCl and provide a non-destructive means of quantitative analysis of CuCl thin films. The best models are shown to match the experimental data quite well, with the closest fits produced when thin film front and rear interfaces are included. This model also accurately simulates the Fabry-Perot fringes present at energies lower than the Z3 free excito...
http://doras.dcu.ie/19622/
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Sub-harmonic injection locking of quantum-dash lasers using spectral enrichment from semiconductor optical amplifiers
(2017)
Srivastava, Manas; Anandarajah, Prince M.; Srinivasan, Balaji; O'Duill, Sean; Venk...
Sub-harmonic injection locking of quantum-dash lasers using spectral enrichment from semiconductor optical amplifiers
(2017)
Srivastava, Manas; Anandarajah, Prince M.; Srinivasan, Balaji; O'Duill, Sean; Venkitesh, Deepa; Landais, Pascal
Abstract:
We report sub-harmonic injection locking of a 40 GHz passively mode-locked quantum-dash (Q-dash) laser through spectral enrichment in a nonlinear semiconductor optical amplifier. The proposed scheme is demonstrated for injection locking of the Q-dash passively mode-locked laser using data modulated with non-returnto-zero line-coding at 10 G symbols/s with both intensity and phase shift keying modulations.
http://doras.dcu.ie/24227/
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Subharmonic all-optical clock recovery of up to 320 Gb/s signal using a quantum dash Fabry–Perot´ mode-locked laser
(2013)
Parra-Cetina, Josué; Luo, Jun; Calabretta, Nicola; Latkowski, Sylwester; Dorren, Harmen...
Subharmonic all-optical clock recovery of up to 320 Gb/s signal using a quantum dash Fabry–Perot´ mode-locked laser
(2013)
Parra-Cetina, Josué; Luo, Jun; Calabretta, Nicola; Latkowski, Sylwester; Dorren, Harmen J.S.; Landais, Pascal
Abstract:
In this study, we provide an experimental assessment of a quantum dash Fabry–Perot´ mode-locked laser for all-optical clock recovery using data streams at 40, 80, 160, and 320 Gb/s. The data streams at 80, 160, and 320 Gb/s are phase coherent signals featuring no spectral component at 40 GHz. The 40 GHz recovered optical clock signal is characterized in terms of phase noise, timing jitter, dynamic power range, and wavelength dependence for the different data rates. Our experiments demonstrate a recovered optical clock signal from a 320 Gb/s data stream with a timing jitter of 94 fs and wavelength detuned by 23 nm. In addition, the performance of the optical time division multiplexing receiver at 80 and 160 Gb/s data signals employing the recovered clock as a demultiplexing control signal and as a clock for the bit-error-rate tester (BERT) is evaluated by bit error rate measurements on the demultiplexed data signals.
http://doras.dcu.ie/24879/
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Synthesis and characterization of nanocrystalline CuCl hybrid films for electroluminescent device fabrication.
(2012)
Alam, Md. Monjarul
Synthesis and characterization of nanocrystalline CuCl hybrid films for electroluminescent device fabrication.
(2012)
Alam, Md. Monjarul
Abstract:
Cuprous (I) chloride (CuCl) is an intensively studied inorganic material, particularly for its excitonic related linear/nonlinear optical processes. This is due in large measure to its very large excitonic binding energies (~190 meV) which are much larger than those of IIIV and IIVI semiconductors resulting in a high stability of the exciton even at room temperature. Thus CuCl should be an extremely efficient light emitter due to exciton mediated electronhole recombination. In this study, CuCl nanocrystals were synthesized, embedded in organic Polysilsesquioxane (PSSQ) matrices, deposited on a variety of substrates via the spin coating method and its properties studied optimized for optical and electrical behaviour. Room temperature Xray diffraction (XRD) confirmed the preferential growth of CuCl nanocrystals whose average radius size was ≈1422 nm in the (111) orientation. Scanning Electron Microscopy (SEM) measurements revealed that the average surface area of the f...
http://doras.dcu.ie/16673/
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Taguchi method modelling of Nd:YAG laser ablation of microchannels on cyclic olefin polymer film
(2018)
McCann, Ronán; Bagga, Komal; Duaux, Gabriel; Stalcup, Apryll; Vázquez, Mercedes; Brabaz...
Taguchi method modelling of Nd:YAG laser ablation of microchannels on cyclic olefin polymer film
(2018)
McCann, Ronán; Bagga, Komal; Duaux, Gabriel; Stalcup, Apryll; Vázquez, Mercedes; Brabazon, Dermot
Abstract:
This paper presents the development of a model for Nd:YAG laser ablation of cyclic olefin polymer (COP) films. Two Taguchi orthogonal array experimental designs were implemented to produce a model for the prediction of microchannel depth and width produced on ZeonorFilm® ZF14 and ZF16 polymer films via laser ablation. The width and depth of the produced microchannels were measured using 3D optical profilometry. Microchannels produced were seen to range in depth of up to 50 µm, and widths of 112 µm via single-pass laser depending on the grade of COP, with feature size increasing as the number of laser passes increased. The models are discussed in terms of adjusted coefficient of determination, signal to noise ratio and model significance. The effect of the process parameters used such as fluence and scan speed on three different grades of COP was examined with an aim to produce a simple model suitable for predictive control of surface microstructuring of COP.
http://doras.dcu.ie/22221/
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Terahertz wave generation from a dc-biased multimode laser
(2008)
Latkowski, Sylwester; Surre, Frederic; Landais, Pascal
Terahertz wave generation from a dc-biased multimode laser
(2008)
Latkowski, Sylwester; Surre, Frederic; Landais, Pascal
Abstract:
We present results achieved in the generation of terahertz wave by a semiconductor laser. It is a Fabry–Pérot based device with shallow grooves implemented on its p-side to engineer the longitudinal mode spectrum. The laser is dc-biased and temperature controlled at 298 K. The main two modes are separated by 3 nm at 1550 nm with a side-mode-suppression ratio of 25 dB. Using a frequency resolved optical gating, evidence of mode beating at 373 GHz is observed. With a bolometer interfaced to a Fourier transform interferometer, the second harmonic signal is measured at 690 GHz.
http://doras.dcu.ie/24223/
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Tetrahedral framework of inverse opal photonic crystals defines the optical response and photonic band gap
(2018)
Lonergan, Alex; McNulty, David; O'Dwyer, Colm
Tetrahedral framework of inverse opal photonic crystals defines the optical response and photonic band gap
(2018)
Lonergan, Alex; McNulty, David; O'Dwyer, Colm
Abstract:
By forming anatase TiO2 inverse opals by infiltration of an opal photonic crystal, we demonstrate that the optical response and angle-resolved blue-shift of the band-gap of the inverse opal structure are defined by a particular three-dimensional structure of the infilled voids. The optical structure of TiO2 inverse opals usually displays significant deviation from its physical structure and from the theoretically predicted position of the photonic band-gap. Following rigorous structural characterization of the parent opal template and TiO2 inverse opals, alternative explanations for the signature of optical transmission through inverse opals are proposed. These approaches posit that, for light-matter interaction, an inverse opal is not precisely the inverse of an opal. Accurate parameters for the structure and material properties can be obtained by invoking a Bragg FCC selection rule-forbidden (-211) plane, which is not a realistic model for diffraction in the IO. Alternatively, by ...
http://hdl.handle.net/10468/6735
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