Special Issue "Ultrafast Laser Pulses"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: 30 April 2019

Special Issue Editors

Guest Editor
Dr. Poletto Luca

National Research Council, Institute of Photonics and Nanotechnologies, via Trasea 7, 35131 Padova, Italy
Website | E-Mail
Interests: XUV ultrafast optics; XUV ultrafast spectroscopy; generation of femto- and attosecond pulses; ultrafast pulse conditioning
Guest Editor
Dr. Fabio Frassetto

National Research Council, Institute of Photonics and Nanotechnologies, via Trasea 7, 35131 Padova, Italy
Website | E-Mail
Interests: XUV ultrafast spectroscopy; XUV ultrafast optics; generation of femto- and attosecond pulses; ultrafast pulse conditioning

Special Issue Information

Dear Colleagues,

It is a great pleasure, and an honor, to present this Special Issue of Applied Sciences, “Ultrafast Laser Pulses”. This is a special feature issue to present recent advances in the generation and utilization of ultrafast laser pulses and future prospects of this key, fundamental, research area. All interested authors are invited to submit their newest results on ultrafast laser pulses for possible publication in this Special Issue. All papers need to present original, previously-unpublished work and will be subject to the normal standards and peer-review processes of this journal (including the usual fees). There is the possibility of accepting a few review papers; prospective authors are encouraged to submit their review proposals. Potential topics include, but are not limited to:

  • Design and modeling of ultrafast laser systems
  • Power scaling of pulsed lasers
  • Fiber and waveguide lasers for ultrafast pulses
  • Frequency conversion techniques
  • CPA and OPCPA laser technologies
  • High-repetition high-power ultrafast laser systems
  • New techniques to measure ultrafast pulses
  • Applications of ultrafast lasers
  • Ultrafast pump-probe spectroscopy
  • Ultrafast imaging
  • Material machining and processing with ultrafast laser pulses
  • Generation of extreme-ultraviolet and soft X-ray radiation with ultrafast lasers
Dr. Poletto Luca
Dr. Fabio Frassetto
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Ultrafast lasers
  • Pulsed lasers
  • Ultrafast pump-probe techniques
  • Ultrafast material machining
  • Fiber lasers
  • Optical Parametric Chirped-Pulse Amplification
  • High-order harmonic generation

Published Papers (11 papers)

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Research

Jump to: Review

Open AccessArticle Step-Pulse Modulation of Gain-Switched Semiconductor Pulsed Laser
Appl. Sci. 2019, 9(3), 602; https://doi.org/10.3390/app9030602
Received: 12 December 2018 / Revised: 2 February 2019 / Accepted: 8 February 2019 / Published: 12 February 2019
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Abstract
To improve the peak power and extinction ratio and produce ultra-short pulses, a novel approach is presented in this paper offers a highly effective modulated method for a gain-switched semiconductor laser by using step-pulse signal modulation. For the purpose of single pulse output, [...] Read more.
To improve the peak power and extinction ratio and produce ultra-short pulses, a novel approach is presented in this paper offers a highly effective modulated method for a gain-switched semiconductor laser by using step-pulse signal modulation. For the purpose of single pulse output, then the effects on the output from the gain-switched semiconductor laser are studied by simulating single mode rate equation when changing the amplitude and width of the modulated signal. The results show that the proposed method can effectively accelerate the accumulation speed of the population inversion and we can acquire the output pulse with higher peak power and shorter width. Compared with the traditional rectangular wave modulation, this method is advantageous to obtain a high gain switching effect by increasing the second modulation current and reduce the pulse width to saturation at the best working point. It can be incorporated as a practical and cost-effective approach for many fields which need high extinction ratio short pulse, such as the optical time domain reflectometry. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessArticle Analytical Solutions for the Propagation of UltraShort and UltraSharp Pulses in Dispersive Media
Appl. Sci. 2019, 9(3), 527; https://doi.org/10.3390/app9030527
Received: 13 January 2019 / Revised: 28 January 2019 / Accepted: 29 January 2019 / Published: 4 February 2019
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Abstract
Ultrashort pulses are severely distorted even by low dispersive media. While the mathematical analysis of dispersion is well known, the technical literature focuses on pulses, Gaussian and Airy pulses, which keep their shape. However, the cases where the shape of the pulse is [...] Read more.
Ultrashort pulses are severely distorted even by low dispersive media. While the mathematical analysis of dispersion is well known, the technical literature focuses on pulses, Gaussian and Airy pulses, which keep their shape. However, the cases where the shape of the pulse is unaffected by dispersion is the exception rather than the norm. It is the objective of this paper to present a variety of pulse profiles, which have analytical expressions but can simulate real-physical pulses with great accuracy. In particular, the dynamics of smooth rectangular pulses, physical Nyquist-Sinc pulses, and slowly rising but sharply decaying ones (and vice versa) are presented. Besides the usage of this paper as a handbook of analytical expressions for pulse propagations in a dispersive medium, there are several new findings. The main findings are the analytical expressions for the propagation of chirped rectangular pulses, which converge to extremely short pulses; an analytical approximation for the propagation of super-Gaussian pulses; the propagation of the Nyquist-Sinc Pulse with smooth spectral boundaries; and an analytical expression for a physical realization of an attenuation compensating Airy pulse. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessFeature PaperArticle Spin-ARPES EUV Beamline for Ultrafast Materials Research and Development
Appl. Sci. 2019, 9(3), 370; https://doi.org/10.3390/app9030370
Received: 12 December 2018 / Revised: 11 January 2019 / Accepted: 15 January 2019 / Published: 22 January 2019
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Abstract
A new femtosecond, Extreme Ultraviolet (EUV), Time Resolved Spin-Angle Resolved Photo-Emission Spectroscopy (TR-Spin-ARPES) beamline was developed for ultrafast materials research and development. This 50-fs laser-driven, table-top beamline is an integral part of the “Ultrafast Spintronic Materials Facility”, dedicated to engineering ultrafast materials. This [...] Read more.
A new femtosecond, Extreme Ultraviolet (EUV), Time Resolved Spin-Angle Resolved Photo-Emission Spectroscopy (TR-Spin-ARPES) beamline was developed for ultrafast materials research and development. This 50-fs laser-driven, table-top beamline is an integral part of the “Ultrafast Spintronic Materials Facility”, dedicated to engineering ultrafast materials. This facility provides a fast and in-situ analysis and development of new materials. The EUV source based on high harmonic generation process emits 2.3 × 1011 photons/second (2.3 × 108 photons/pulse) at H23 (35.7 eV) and its photon energy ranges from 10 eV to 75 eV, which enables surface sensitive studies of the electronic structure dynamics. The EUV monochromator provides the narrow bandwidth of the EUV beamline while preserving its pulse duration in an energy range of 10–100 eV. Ultrafast surface photovoltaic effect with ~650 fs rise-time was observed in p-GaAs (100) from time-resolved ARPES spectra. The data acquisition time could be reduced by over two orders of magnitude by scaling the laser driver from 1 KHz, 4W to MHz, KW average power. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessArticle 500-kHz Level High Energy Double-Pass Nd:YVO4 Picosecond Amplifier with Optic–Optic Efficiency of 51%
Appl. Sci. 2019, 9(2), 219; https://doi.org/10.3390/app9020219
Received: 10 December 2018 / Revised: 28 December 2018 / Accepted: 29 December 2018 / Published: 9 January 2019
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Abstract
We have demonstrated a high pulse energy and high optic–optic efficiency double-pass picosecond (ps) master oscillator power amplifier system of 1064 nm at a pulse repetition rate of 500 kHz. A 500 kHz, 7.68 μJ picosecond laser is used as the seed laser. [...] Read more.
We have demonstrated a high pulse energy and high optic–optic efficiency double-pass picosecond (ps) master oscillator power amplifier system of 1064 nm at a pulse repetition rate of 500 kHz. A 500 kHz, 7.68 μJ picosecond laser is used as the seed laser. Through one stage double-pass traveling-wave amplifier, a maximum output power of 16.19 W at a pump power of 31.7 W is generated with the optic–optic efficiency of 51.07%. The output pulse duration is 17.6 ps, corresponding to the pulse energy of 32.38 μJ. The beam quality factor M 2 were measured to be 1.28 and 1.17 along the x, y axis direction, respectively. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessArticle Low Threshold Plasmonic Nanolaser Based on Graphene
Appl. Sci. 2018, 8(11), 2186; https://doi.org/10.3390/app8112186
Received: 13 October 2018 / Revised: 2 November 2018 / Accepted: 2 November 2018 / Published: 8 November 2018
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Abstract
A hybrid plasmonic nanolaser based on nanowire/air slot/semicircular graphene and metal wire structure was designed. In this structure, the waveguides in the nanowires and the graphene-metal interface are coupled to form a hybrid plasma mode, which effectively reduces the metal loss. The mode [...] Read more.
A hybrid plasmonic nanolaser based on nanowire/air slot/semicircular graphene and metal wire structure was designed. In this structure, the waveguides in the nanowires and the graphene-metal interface are coupled to form a hybrid plasma mode, which effectively reduces the metal loss. The mode and strong coupling of the laser are analyzed by using the finite-element method. Its electric field distribution, propagation loss, normalized mode area, quality factor, and lasing threshold are studied with the different geometric model. Simulation results reveal that the performance of the laser using this structure can be optimized by adjusting the model parameters. Under the optimal parameters, the effective propagation loss is only 0.0096, and the lasing threshold can be as low as 0.14 μm−1. This structure can achieve deep sub-wavelength confinement and low-loss transmission, and provides technical support for the miniaturization and integration of nano-devices. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessArticle Design of Surface Plasmon Nanolaser Based on MoS2
Appl. Sci. 2018, 8(11), 2110; https://doi.org/10.3390/app8112110
Received: 2 October 2018 / Revised: 11 October 2018 / Accepted: 11 October 2018 / Published: 1 November 2018
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Abstract
The paper has proposed a new structure based on MoS2. The electric field distribution, the locality and the loss of the mode, and the threshold under different geometric shapes and parameters are investigated using COMSOL Multiphysics software, based on the finite [...] Read more.
The paper has proposed a new structure based on MoS2. The electric field distribution, the locality and the loss of the mode, and the threshold under different geometric shapes and parameters are investigated using COMSOL Multiphysics software, based on the finite element method. The different influenced degree of each component is also analyzed. Simulation results reveal that this kind of nanolaser has a low loss and high field confinement ability, the radius of CdS and Ag make a major contribution to the low loss and low threshold, and field confinement ability is mainly affected by the height of air gap. Under optimal parameters, effective propagation loss is only 0.00013, and the lasing threshold can be as low as 0.11 μm−1. The results provide theory and technique support to the field of new nanolaser design. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessArticle Quality-Improved GaN Epitaxial Layers Grown on Striped Patterned Sapphire Substrates Ablated by Femtosecond Laser
Appl. Sci. 2018, 8(10), 1842; https://doi.org/10.3390/app8101842
Received: 29 August 2018 / Revised: 26 September 2018 / Accepted: 28 September 2018 / Published: 8 October 2018
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Abstract
In this work, we propose a new approach to create striped patterned sapphire substrate (PSS) under the circumstance that grooved patterned sapphire substrate technology exhibits more potential to reduce dislocation density in GaN (gallium nitride) epilayers. The striped grooves of patterned sapphire substrate [...] Read more.
In this work, we propose a new approach to create striped patterned sapphire substrate (PSS) under the circumstance that grooved patterned sapphire substrate technology exhibits more potential to reduce dislocation density in GaN (gallium nitride) epilayers. The striped grooves of patterned sapphire substrate are ablated by femtosecond laser. After the process of metal-organic chemical vapor deposition (MOCVD) method, the c-plane GaN epitaxial layers grown on striped PSS have larger crystallite size, which brings much less crystal boundary. There is much less compressive stress between the GaN crystals which improves the smoothness and compactness of GaN epilayers. This result demonstrates a significant improvement in the crystallinity of the c-plane GaN epitaxial layers grown on striped PSS. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessArticle Ablation of Copper Metal Films by Femtosecond Laser Multipulse Irradiation
Appl. Sci. 2018, 8(10), 1826; https://doi.org/10.3390/app8101826
Received: 30 August 2018 / Revised: 11 September 2018 / Accepted: 12 September 2018 / Published: 5 October 2018
Cited by 1 | PDF Full-text (848 KB) | HTML Full-text | XML Full-text
Abstract
Ablation of copper using multipulse femtosecond laser irradiation with an 800 nm wavelength and 120-fs pulse duration is investigated theoretically. A two-temperature model, which includes dynamic optical and thermal-physical properties, is considered. The numerical results of the material thermal response obtained by varying [...] Read more.
Ablation of copper using multipulse femtosecond laser irradiation with an 800 nm wavelength and 120-fs pulse duration is investigated theoretically. A two-temperature model, which includes dynamic optical and thermal-physical properties, is considered. The numerical results of the material thermal response obtained by varying the pulse number, the separation times between pulses and laser fluences are presented. Our results show that the increasing of pulse number with a separation time less than the thermal relaxation time can dramatically enhance the lattice temperature without a noticeable increase in ablation depth. Therefore, we suggest that the vaporization rate can be augmented in comparison to the melting rate during the same single-phase explosion at the same total fluence where a fast heat accumulation effect plays an important role for cleaner ablation during micromachining. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessFeature PaperArticle Multidimensional Analysis of Time-Resolved Charged Particle Imaging Experiments
Appl. Sci. 2018, 8(8), 1227; https://doi.org/10.3390/app8081227
Received: 13 June 2018 / Revised: 20 July 2018 / Accepted: 23 July 2018 / Published: 26 July 2018
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Abstract
We present a tutorial to realize a multidimensional fitting procedure capable of extracting all the relevant information contained in a sequence of charged particle images acquired as a function of time in femtosecond pump–probe experiments. The images are reproduced using a 3D fitting [...] Read more.
We present a tutorial to realize a multidimensional fitting procedure capable of extracting all the relevant information contained in a sequence of charged particle images acquired as a function of time in femtosecond pump–probe experiments. The images are reproduced using a 3D fitting method, which provides the velocity (or center-of-mass kinetic energy) and angular distributions contained in the images and their time evolution. A detailed example of the method is shown through the analysis of the time-resolved predissociation dynamics of CH3I on the B-band origin (Gitzinger et al., J. Chem. Phys.2010, 133, 234313). We show that the multidimensional approach is essential for the analysis of complex images that contain several overlapping contributions where reduced dimensionality analyses cannot provide a reliable description of the features present in the image sequence. This methodology can be generalized to many types of multidimensional data analysis. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Open AccessArticle Stable Q-Switched Mode-Locking of 2.7 μm Er:Y2O3 Ceramic Laser Using a Semiconductor Saturable Absorber
Appl. Sci. 2018, 8(7), 1155; https://doi.org/10.3390/app8071155
Received: 20 June 2018 / Revised: 8 July 2018 / Accepted: 9 July 2018 / Published: 17 July 2018
Cited by 1 | PDF Full-text (1812 KB) | HTML Full-text | XML Full-text
Abstract
This paper studies synchronous Q-switch and mode-locking of an 2.7 μm Er:Y2O3 ceramic laser pumped with a high brightness 976 nm fiber laser and using a semiconductor saturable absorber mirror. The Er:Y2O3 ceramic is home-developed with Er [...] Read more.
This paper studies synchronous Q-switch and mode-locking of an 2.7 μm Er:Y2O3 ceramic laser pumped with a high brightness 976 nm fiber laser and using a semiconductor saturable absorber mirror. The Er:Y2O3 ceramic is home-developed with Er3+ doping concentration of 7 at.%. The laser generated ~92 mW of average output power with stable mode-locked pulses of 100% modulation depth and 130 MHz repetition rate embedded inside Q-switched envelopes of ~1.2 μs width. Repetition rates of the Q-switched pulse envelopes are tunable from 5.1 kHz to 29 kHz with the width varying from 2.7 μs to 1.2 μs. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Review

Jump to: Research

Open AccessReview Surface Plasmon Nanolaser: Principle, Structure, Characteristics and Applications
Appl. Sci. 2019, 9(5), 861; https://doi.org/10.3390/app9050861
Received: 25 January 2019 / Revised: 17 February 2019 / Accepted: 22 February 2019 / Published: 28 February 2019
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Abstract
Photonic devices are becoming more and more miniaturized and highly integrated with the advancement of micro-nano technology and the rapid development of integrated optics. Traditional semiconductor lasers have diffraction limit due to the feedback from the optical system, and their cavity length is [...] Read more.
Photonic devices are becoming more and more miniaturized and highly integrated with the advancement of micro-nano technology and the rapid development of integrated optics. Traditional semiconductor lasers have diffraction limit due to the feedback from the optical system, and their cavity length is more than half of the emission wavelength, so it is difficult to achieve miniaturization. Nanolasers based on surface plasmons can break through the diffraction limit and achieve deep sub-wavelength or even nano-scale laser emission. The improvement of modern nanomaterial preparation processes and the gradual maturity of micro-nano machining technology have also provided technical conditions for the development of sub-wavelength and nano-scale lasers. This paper describes the basic principles of surface plasmons and nano-resonators. The structure and characteristics of several kinds of plasmonic nanolasers are discussed. Finally, the paper looks forward to the application and development trend of nanolasers. Full article
(This article belongs to the Special Issue Ultrafast Laser Pulses)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Article Type: Article
Title: High repetition rate THz generation in GaP driven by modelocked thin-disk oscillators: scaling laws and future directions
Authors: Frank Meyer*, Negar Hekmat, Samira Mansourzadeh, Felix Fobbe, Martin Hoffmann, and Clara J. Saraceno
Affiliation: Photonics and Ultrafast Laser Science, Ruhr Universität Bochum, Germany; [email protected]; Tel.: +49-234-32-29498
Abstract: Sources of few or single-cycle THz pulses driven by near-infrared ultrafast lasers have enabled THz time domain spectroscopy to emerge as a powerful tool for a variety of applications in science and technology. However, many of these applications would strongly benefit from the availability of higher power THz sources. Current state of the art sources are limited to relatively low average powers on the mW level and below, mainly due to the power limitations inherent in the Ti:Sa laser technology, that is most commonly used to drive these sources. We recently demonstrated THz generation by optical rectification in GaP with an excitation power of more than 100 W using an Yb:YAG modelocked thin-disk oscillator. In this contribution we systematically investigate the power scaling limitations in this simple geometry and draw conclusions about its applicability to more advanced generation schemes like the tilted pulse front method in lithium niobate.
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