Showing papers on "Laser published in 2004"
TL;DR: HBN is shown to be a promising material for compact ultraviolet laser devices because it has a direct bandgap in the ultraviolet region and evidence for room-temperature ultraviolet lasing at 215 nm by accelerated electron excitation is provided.
Abstract: The demand for compact ultraviolet laser devices is increasing, as they are essential in applications such as optical storage, photocatalysis, sterilization, ophthalmic surgery and nanosurgery. Many researchers are devoting considerable effort to finding materials with larger bandgaps than that of GaN. Here we show that hexagonal boron nitride (hBN) is a promising material for such laser devices because it has a direct bandgap in the ultraviolet region. We obtained a pure hBN single crystal under high-pressure and high-temperature conditions, which shows a dominant luminescence peak and a series of s-like exciton absorption bands around 215 nm, proving it to be a direct-bandgap material. Evidence for room-temperature ultraviolet lasing at 215 nm by accelerated electron excitation is provided by the enhancement and narrowing of the longitudinal mode, threshold behaviour of the excitation current dependence of the emission intensity, and a far-field pattern of the transverse mode.
2,550 citations
TL;DR: A laser accelerator that produces electron beams with an energy spread of a few per cent, low emittance and increased energy (more than 109 electrons above 80 MeV) and opens the way for compact and tunable high-brightness sources of electrons and radiation.
Abstract: Laser-driven accelerators, in which particles are accelerated by the electric field of a plasma wave (the wakefield) driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV m-1 (refs 1–3) These fields are thousands of times greater than those achievable in conventional radio-frequency accelerators, spurring interest in laser accelerators4,5 as compact next-generation sources of energetic electrons and radiation To date, however, acceleration distances have been severely limited by the lack of a controllable method for extending the propagation distance of the focused laser pulse The ensuing short acceleration distance results in low-energy beams with 100 per cent electron energy spread1,2,3, which limits potential applications Here we demonstrate a laser accelerator that produces electron beams with an energy spread of a few per cent, low emittance and increased energy (more than 109 electrons above 80 MeV) Our technique involves the use of a preformed plasma density channel to guide a relativistically intense laser, resulting in a longer propagation distance The results open the way for compact and tunable high-brightness sources of electrons and radiation
1,749 citations
TL;DR: High-resolution energy measurements of the electron beams produced from intense laser–plasma interactions are reported, showing that—under particular plasma conditions—it is possible to generate beams of relativistic electrons with low divergence and a small energy spread.
Abstract: High-power lasers that fit into a university-scale laboratory can now reach focused intensities of more than 10(19) W cm(-2) at high repetition rates. Such lasers are capable of producing beams of energetic electrons, protons and gamma-rays. Relativistic electrons are generated through the breaking of large-amplitude relativistic plasma waves created in the wake of the laser pulse as it propagates through a plasma, or through a direct interaction between the laser field and the electrons in the plasma. However, the electron beams produced from previous laser-plasma experiments have a large energy spread, limiting their use for potential applications. Here we report high-resolution energy measurements of the electron beams produced from intense laser-plasma interactions, showing that--under particular plasma conditions--it is possible to generate beams of relativistic electrons with low divergence and a small energy spread (less than three per cent). The monoenergetic features were observed in the electron energy spectrum for plasma densities just above a threshold required for breaking of the plasma wave. These features were observed consistently in the electron spectrum, although the energy of the beam was observed to vary from shot to shot. If the issue of energy reproducibility can be addressed, it should be possible to generate ultrashort monoenergetic electron bunches of tunable energy, holding great promise for the future development of 'table-top' particle accelerators.
1,739 citations
George Washington University1, Colgate University2, St. John's University3, University of Wisconsin-Madison4, Swedish Museum of Natural History5, University of Göttingen6, National Institute of Advanced Industrial Science and Technology7, University of Mainz8, University of Lausanne9, Open University10, University of Edinburgh11, Utrecht University12, University of Tasmania13, University of Maryland, College Park14, Hiroshima University15, University of Tübingen16, University of Saskatchewan17, University of Science and Technology of China18
TL;DR: In this article, the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometer (LA-ICP-MS), secondary ion mass spectrometry (SIMS), and laser fluorination analyses, were reported.
Abstract: This paper reports the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS) and laser fluorination analyses. The focus of this initiative was to establish the suitability of this large single zircon crystal for calibrating in situ analyses of the rare earth elements and oxygen isotopes, as well as to provide working values for key geochemical systems. In addition to extensive testing of the chemical and structural homogeneity of this sample, the occurrence of banding in 91500 in both backscattered electron and cathodoluminescence images is described in detail. Blind intercomparison data reported by both LA-ICP-MS and SIMS laboratories indicate that only small systematic differences exist between the data sets provided by these two techniques. Furthermore, the use of NIST SRM 610 glass as the calibrant for SIMS analyses was found to introduce little or no systematic error into the results for zircon. Based on both laser fluorination and SIMS data, zircon 91500 seems to be very well suited for calibrating in situ oxygen isotopic analyses.
1,131 citations
TL;DR: With the current ∼750-nm laser probe and ∼100-eV excitation, the transient recorder is capable of resolving atomic electron dynamics within the Bohr orbit time.
Abstract: In Bohr's model of the hydrogen atom, the electron takes about 150 attoseconds (1 as = 10(-18) s) to orbit around the proton, defining the characteristic timescale for dynamics in the electronic shell of atoms. Recording atomic transients in real time requires excitation and probing on this scale. The recent observation of single sub-femtosecond (1 fs = 10(-15) s) extreme ultraviolet (XUV) light pulses has stimulated the extension of techniques of femtochemistry into the attosecond regime. Here we demonstrate the generation and measurement of single 250-attosecond XUV pulses. We use these pulses to excite atoms, which in turn emit electrons. An intense, waveform-controlled, few cycle laser pulse obtains 'tomographic images' of the time-momentum distribution of the ejected electrons. Tomographic images of primary (photo)electrons yield accurate information of the duration and frequency sweep of the excitation pulse, whereas the same measurements on secondary (Auger) electrons will provide insight into the relaxation dynamics of the electronic shell following excitation. With the current approximately 750-nm laser probe and approximately 100-eV excitation, our transient recorder is capable of resolving atomic electron dynamics within the Bohr orbit time.
1,119 citations
TL;DR: In this paper, the spectral distribution and time-dependent decay of light emitted from excitons confined in the quantum dots are controlled by the host photonic crystal, and both inhibited and enhanced decay rates are observed depending on the optical emission frequency.
Abstract: Control of spontaneously emitted light lies at the heart of quantum optics. It is essential for diverse applications ranging from miniature lasers and light-emitting diodes, to single-photon sources for quantum information, and to solar energy harvesting. To explore such new quantum optics applications, a suitably tailored dielectric environment is required in which the vacuum fluctuations that control spontaneous emission can be manipulated. Photonic crystals provide such an environment: they strongly modify the vacuum fluctuations, causing the decay of emitted light to be accelerated or slowed down, to reveal unusual statistics, or to be completely inhibited in the ideal case of a photonic bandgap. Here we study spontaneous emission from semiconductor quantum dots embedded in inverse opal photonic crystals. We show that the spectral distribution and time-dependent decay of light emitted from excitons confined in the quantum dots are controlled by the host photonic crystal. Modified emission is observed over large frequency bandwidths of 10%, orders of magnitude larger than reported for resonant optical microcavities. Both inhibited and enhanced decay rates are observed depending on the optical emission frequency, and they are controlled by the crystals’ lattice parameter. Our experimental results provide a basis for all-solid-state dynamic control
of optical quantum systems.
1,046 citations
Journal Article•
TL;DR: This work shows that the spectral distribution and time-dependent decay of light emitted from excitons confined in the quantum dots are controlled by the host photonic crystal, providing a basis for all-solid-state dynamic control of optical quantum systems.
Abstract: Control of spontaneously emitted light lies at the heart of quantum optics. It is essential for diverse applications ranging from miniature lasers and light-emitting diodes, to single-photon sources for quantum information, and to solar energy harvesting. To explore such new quantum optics applications, a suitably tailored dielectric environment is required in which the vacuum fluctuations that control spontaneous emission can be manipulated. Photonic crystals provide such an environment: they strongly modify the vacuum fluctuations, causing the decay of emitted light to be accelerated or slowed down, to reveal unusual statistics, or to be completely inhibited in the ideal case of a photonic bandgap. Here we study spontaneous emission from semiconductor quantum dots embedded in inverse opal photonic crystals. We show that the spectral distribution and time-dependent decay of light emitted from excitons confined in the quantum dots are controlled by the host photonic crystal. Modified emission is observed over large frequency bandwidths of 10%, orders of magnitude larger than reported for resonant optical microcavities. Both inhibited and enhanced decay rates are observed depending on the optical emission frequency, and they are controlled by the crystals’ lattice parameter. Our experimental results provide a basis for all-solid-state dynamic control
of optical quantum systems.
1,019 citations
TL;DR: An intense laser-plasma interaction regime of the generation of high density ultrashort relativistic ion beams is suggested and it is suggested that the laser energy is transformed efficiently into the energy of fast ions.
Abstract: An intense laser-plasma interaction regime of the generation of high density ultrashort relativistic ion beams is suggested. When the radiation pressure is dominant, the laser energy is transformed efficiently into the energy of fast ions.
951 citations
TL;DR: A highly-efficient cladding-pumped ytterbium-doped fiber laser generating 1.36 kW of continuous-wave output power at 1.1 mum with 83% slope efficiency and near diffraction-limited beam quality is demonstrated.
Abstract: We have demonstrated a highly-efficient cladding-pumped ytterbium-doped fiber laser generating 1.36 kW of continuous-wave output power at 1.1 µm with 83% slope efficiency and near diffraction-limited beam quality. The laser was end-pumped through both fiber ends and showed no evidence of roll-over even at the highest output power, which was limited only by available pump power.
887 citations
TL;DR: The experimental demonstration of an electrically driven, single-mode, low threshold current (∼260 μA) photonic band gap laser operating at room temperature is reported, a small step toward a thresholdless laser or a single photon source.
Abstract: We report the experimental demonstration of an electrically driven, single-mode, low threshold current (∼260 μA) photonic band gap laser operating at room temperature. The electrical current pulse is injected through a sub-micrometer-sized semiconductor wire at the center of the mode with minimal degradation of the quality factor. The actual mode of interest operates in a nondegenerate monopole mode, as evidenced through the comparison of the measurement with the computation based on the actual fabricated structural parameters. As a small step toward a thresholdless laser or a single photon source, this wavelength-size photonic crystal laser may be of interest to photonic crystals, cavity quantum electrodynamics, and quantum information communities.
831 citations
TL;DR: The demonstration of the first silicon Raman laser using a silicon waveguide as the gain medium and has a clear threshold at 9 W peak pump pulse power and a slope efficiency of 8.5%.
Abstract: We report the demonstration of the first silicon Raman laser. Experimentally, pulsed Raman laser emission at 1675 nm with 25 MHz repetition rate is demonstrated using a silicon waveguide as the gain medium. The laser has a clear threshold at 9 W peak pump pulse power and a slope efficiency of 8.5%.
TL;DR: The first version of the IUPAC technical report on chemical actinometers was published in Pure Appl Chem 61, 187-210 (1989) as mentioned in this paper, and since then some methods have been improved, procedures have been modified, and new substances have been proposed as chemical act-inometers.
Abstract: This document updates the first version of the IUPAC technical report on "Chemical actinometers" published in Pure Appl Chem 61, 187-210 (1989) Since then, some methods have been improved, procedures have been modified, and new substances have been proposed as chemical actinometers An actinometer is a chemical system or a physical device by which the number of photons in a beam absorbed into the defined space of a chemical reactor can be determined integrally or per time This compilation includes chemical actinometers for the gas, solid, microheterogeneous, and liquid phases, as well as for the use with pulsed lasers for the measurement of transient absorbances, including the quantum yield of phototransformation, as well as the literature for each of the actinometers The actinometers listed are for the use in the wavelength range from the UV to the red region of the spectrum A set of recommended standard procedures is also given Advantages and disadvantages are discussed regarding the use of chemical actinometers vs electronic devices for the measurement of the number of photons absorbed Procedures for the absolute measurement of incident photon flux by means of photodiodes are also discussed
TL;DR: A novel type of Fourier-transform infrared spectrometer based on two Ti:sapphire lasers emitting femtosecond pulse trains with slightly different repetition frequencies that superimposed upon a detector to produce purely time-domain interferograms that encode the infrared spectrum is demonstrated.
Abstract: A novel type of Fourier-transform infrared spectrometer (FTIR) is demonstrated. It is based on two Ti:sapphire lasers emitting femtosecond pulse trains with slightly different repetition frequencies. Two mid-infrared beams-derived from those lasers by rectification in GaSe-are superimposed upon a detector to produce purely time-domain interferograms that encode the infrared spectrum. The advantages of this spectrometer compared with the common FTIR include ease of operation (no moving parts), speed of acquisition (100 micros demonstrated), and not-yet-shown collimated long-distance propagation, diffraction-limited microscopic probing, and electronically controllable chemometric factoring. Extending time-domain frequency-comb spectroscopy to lower (terahertz) or higher (visible, ultraviolet) frequencies should be feasible.
28 Sep 2004
TL;DR: A direct solution is given that minimizes an algebraic error from this constraint, and subsequent nonlinear refinement minimizes a re-projection error, which is the first published calibration tool for this problem.
Abstract: We describe theoretical and experimental results for the extrinsic calibration of sensor platform consisting of a camera and a 2D laser range finder. The calibration is based on observing a planar checkerboard pattern and solving for constraints between the "views" of a planar checkerboard calibration pattern from a camera and laser range finder. We give a direct solution that minimizes an algebraic error from this constraint, and subsequent nonlinear refinement minimizes a re-projection error. To our knowledge, this is the first published calibration tool for this problem. Additionally we show how this constraint can reduce the variance in estimating intrinsic camera parameters.
TL;DR: This work demonstrates a versatile technique for imaging nanostructures, based on the use of resonantly tuned soft X-rays for scattering contrast and the direct Fourier inversion of a holographically formed interference pattern, which is a form of Fourier transform holography and appears scalable to diffraction-limited resolution.
Abstract: Our knowledge of the structure of matter is largely based on X-ray diffraction studies of periodic structures and the successful transformation (inversion) of the diffraction patterns into real-space atomic maps. But the determination of non-periodic nanoscale structures by X-rays is much more difficult. Inversion of the measured diffuse X-ray intensity patterns suffers from the intrinsic loss of phase information, and direct imaging methods are limited in resolution by the available X-ray optics. Here we demonstrate a versatile technique for imaging nanostructures, based on the use of resonantly tuned soft X-rays for scattering contrast and the direct Fourier inversion of a holographically formed interference pattern. Our implementation places the sample behind a lithographically manufactured mask with a micrometre-sized sample aperture and a nanometre-sized hole that defines a reference beam. As an example, we have used the resonant X-ray magnetic circular dichroism effect to image the random magnetic domain structure in a Co/Pt multilayer film with a spatial resolution of 50 nm. Our technique, which is a form of Fourier transform holography, is transferable to a wide variety of specimens, appears scalable to diffraction-limited resolution, and is well suited for ultrafast single-shot imaging with coherent X-ray free-electron laser sources.
TL;DR: It is demonstrated that a beam of x-ray radiation can be generated by simply focusing a single high-intensity laser pulse into a gas jet, which has keV energy and lies within a narrow cone angle.
Abstract: We demonstrate that a beam of x-ray radiation can be generated by simply focusing a single high-intensity laser pulse into a gas jet. A millimeter-scale laser-produced plasma creates, accelerates, and wiggles an ultrashort and relativistic electron bunch. As they propagate in the ion channel produced in the wake of the laser pulse, the accelerated electrons undergo betatron oscillations, generating a femtosecond pulse of synchrotron radiation, which has keV energy and lies within a narrow (50 mrad) cone angle.
TL;DR: In this article, a carrier-envelope offset (CEO) phase locked few-cycle pulses are generated using self-guiding of intense 43-fs, 0.84 mJ optical pulses during propagation in a transparent noble gas.
Abstract: Intense, well-controlled light pulses with only a few optical cycles start to play a crucial role in many fields of physics, such as attosecond science. We present an extremely simple and robust technique to generate such carrier-envelope offset (CEO) phase locked few-cycle pulses, relying on self-guiding of intense 43-fs, 0.84 mJ optical pulses during propagation in a transparent noble gas. We have demonstrated 5.7-fs, 0.38 mJ pulses with an excellent spatial beam profile and discuss the potential for much shorter pulses. Numerical simulations confirm that filamentation is the mechanism responsible for pulse shortening. The method is widely applicable and much less sensitive to experimental conditions such as beam alignment, input pulse duration or gas pressure as compared to gas-filled hollow fibers.
TL;DR: In this paper, the most important properties of lithium niobate crystals for photonic applications are reviewed, acting on stoichiometry, sample structure, doping and domain structure of the crystals, these properties are governed, and can be taylored for each specific application.
Abstract: In this paper the most important properties of lithium niobate crystals for photonic applications are reviewed. We will summarize how acting on the stoichiometry, sample structure, doping and domain structure of the crystals, these properties are governed, and can be taylored for each specific application. Finally we present a review of photonic applications in a wide spectrum of fields as lasers and non-linear optics, optical communications, optical memories, and diffractive optics.
01 Jan 2004
TL;DR: In this article, the authors describe a new class of saturable absorber device based on single-wall carbon nanotube (SWNT)-the saturable absorbing nano tube (SAINT), which possesses ultrafast optical properties comparable to that of the industrial standard semiconductor SESAM.
Abstract: This paper describes a new class of saturable absorber device based on single-wall carbon nanotube (SWNT)-the saturable absorber incorporating nano tube (SAINT). The device possesses ultrafast optical properties comparable to that of the industrial standard semiconductor saturable absorber mirror (SESAM). Passively mode-locked picosecond fiber lasers in different configurations are demonstrated using SAINTs as mode lockers. This is the first demonstration of optical pulsed lasers based on the carbon nanotube technology, and the first practical application of carbon nanotubes in the field of applied optics.
TL;DR: In this paper, a feasibility study was performed both theoretically and experimentally using the Laser Surface Texturing (LST) technique to produce the micro-dimples on their surfaces, which can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication.
Abstract: Significant improvement in load capacity, wear resistance, friction coefficient etc. of tribological mechanical components can be obtained by forming regular micro-surface structure in the form of micro-dimples on their surfaces. A feasibility study was performed both theoretically and experimentally using the Laser Surface Texturing (LST) technique to produce the micro-dimples. Each micro-dimple can serve either as a micro-hydrodynamic bearing in cases of full or mixed lubrication or as a micro-reservoir for lubricant in cases of starved lubrication conditions. Theoretical models were developed, and laboratory tests were performed, to investigate the potential of LST in tribological components like mechanical seals, piston rings and thrust bearings. In the entire laboratory tests, friction was substantially reduced with LST compared to the non-textured components.
TL;DR: In this paper, the ablation threshold fluence depends on the number of pulses applied to the same spot, and the strength of this dependence is governed by the incubation coefficient, S, which has been determined along with the single-shot threshold, φ th (1), for all the metals studied.
TL;DR: The laminarity of high-current multi-MeV proton beams produced by irradiating thin metallic foils with ultraintense lasers has been measured and appears to be at least 100-fold better than conventional accelerator beams.
Abstract: The laminarity of high-current multi-MeV proton beams produced by irradiating thin metallic foils with ultraintense lasers has been measured. For proton energies >10 MeV, the transverse and longitudinal emittance are, respectively, 10 MeV.
TL;DR: The origin of phase stability and the precise calibration of excitation-pulse time delays using movable glass wedges are discussed and it is shown that correlations between different electronically excited states can be determined from the spectra.
Abstract: Two-dimensional (2D) spectroscopy is a powerful technique to study nuclear and electronic correlations between different transitions or initial and final states. Here we describe in detail our development of inherently phase-stabilized 2D Fourier-transform spectroscopy for electronic transitions. A diffractive-optic setup is used to realize heterodyne-detected femtosecond four-wave mixing in a phase-matched box geometry. Wavelength tunability in the visible range is accomplished by means of a 3 kHz repetition-rate laser system and optical parametric amplification. Nonlinear signals are fully characterized by spectral interferometry. Starting from fundamental principles, we discuss the origin of phase stability and the precise calibration of excitation-pulse time delays using movable glass wedges. Automated subtraction of undesired scattering terms removes experimental artifacts. On the theoretical side, the response-function formalism is extended to describe molecules with three electronic levels, and the shape of 2D spectral features is discussed. As an example for this technique, experimental 2D spectra are shown for the dye molecule Nile Blue in acetonitrile at 595 nm, recorded for a series of population times. Simulations explore the influence of different model parameters and qualitatively reproduce the experimental results. We show that correlations between different electronically excited states can be determined from the spectra. The technique described here can be used to measure the third-order response function of complex systems covering several electronic transitions.
TL;DR: In this paper, the authors measured the distribution of residual stress within the model and proposed some methods for reducing the residual stress in order to improve the mechanical properties and dimensional accuracy of the steel model produced by the selective laser melting process.
TL;DR: In this paper, an experimentalist's point of view of the dynamics of H-2+ in an intense laser field is presented, which is interpreted in terms of bond-softening, vibrational trapping (bond-hardening), below-threshold dissociation and laser-induced alignment of the molecular axis.
Abstract: In the past decade, the understanding of the dynamics of small molecules in intense laser fields has advanced enormously. At the same time, the technology of ultra-short pulsed lasers has equally progressed to such an extent that femtosecond lasers are now widely available. This review is written from an experimentalist's point of view and begins by discussing the value of this research and defining the meaning of the word 'intense'. It continues with describing the Ti: sapphire laser, including topics such as pulse compression, chirped pulse amplification, optical parametric amplification, laser-pulse diagnostics and the absolute phase. Further aspects include focusing, the focal volume effect and space charge. The discussion of physics begins with the Keldysh parameter and the three regimes of ionization, i.e. multi-photon, tunnelling and over-the-barrier. Direct-double ionization (non-sequential ionization), high-harmonic generation, above-threshold ionization and attosecond pulses are briefly mentioned. Subsequently, a theoretical calculation, which solves the time-dependent Schrodinger equation, is compared with an experimental result. The dynamics of H-2(+) in an intense laser field is interpreted in terms of bond-softening, vibrational trapping (bond-hardening), below-threshold dissociation and laser-induced alignment of the molecular axis. The final section discusses the modified Franck-Condon principle, enhanced ionization at critical distances and Coulomb explosion of diatomic and triatomic molecules.
TL;DR: A volume sampling method to generate three-dimensional patterns is proposed and a systematic SEM-based analysis of the microstructure gives new insights toward a better understanding of the femtosecond laser interaction with fused silica glass.
Abstract: We present novel results obtained in the fabrication of high-aspect ratio micro-fluidic microstructures chemically etched from fused silica substrates locally exposed to femtosecond laser radiation. A volume sampling method to generate three-dimensional patterns is proposed and a systematic SEM-based analysis of the microstructure is presented. The results obtained gives new insights toward a better understanding of the femtosecond laser interaction with fused silica glass (a-SiO2).
TL;DR: In this article, the power Fourier transform of random laser spectra collected from many excitation locations in the tissue was used to extract a typical random resonator size within the tissue.
Abstract: A random collection of scatterers in a gain medium can produce coherent laser emission lines dubbed “random lasing.” We show that biological tissues, including human tissues, can support coherent random lasing when infiltrated with a concentrated laser dye solution. To extract a typical random resonator size within the tissue we average the power Fourier transform of random laser spectra collected from many excitation locations in the tissue; we verified this procedure by a computer simulation. Surprisingly, we found that malignant tissues show many more laser lines compared to healthy tissues taken from the same organ. Consequently, the obtained typical random resonator was found to be different for healthy and cancerous tissues, and this may lead to a technique for separating malignant from healthy tissues for diagnostic imaging.
TL;DR: An overview of femtosecond laser interactions with dielectrics can be found in this article, where the focus is the dynamics of femto-laser-excited carriers and the propagation of femtecond laser pulses inside dielectric materials.
Abstract: Femtosecond laser pulses appear as an emerging and promising tool for processing wide bandgap dielectric materials for a variety of applications. This article aims to provide an overview of recent progress in understanding the fundamental physics of femtosecond laser interactions with dielectrics that may have the potential for innovative materials applications. The focus of the overview is the dynamics of femtosecond laser-excited carriers and the propagation of femtosecond laser pulses inside dielectric materials.
TL;DR: In this paper, a direct, point-by-point inscription of fibre Bragg gratings by infrared femtosecond laser is reported for the first time, in a non-photosensitised, standard telecommunication fibre and dispersion shifted fibre.
Abstract: Direct, point-by-point inscription of fibre Bragg gratings by infrared femtosecond laser is reported for the first time. Gratings of first to third order have been produced in non-photosensitised, standard telecommunication fibre and dispersion shifted fibre.
TL;DR: High-quality single-walled carbon nanotubes were directly synthesized on quartz substrates and fiber ends and successfully applied the SWNTs to mode lock a fiber laser producing subpicosecond pulses at a 50-MHz repetition rate.
Abstract: We present novel carbon-nanotube-based saturable absorbers. Using the low-temperature alcohol catalytic chemical-vapor deposition method, high-quality single-walled carbon nanotubes (SWNTs) were directly synthesized on quartz substrates and fiber ends. We successfully applied the SWNTs to mode lock a fiber laser producing subpicosecond pulses at a 50-MHz repetition rate.