Special Issue "Laser Crystals"

A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (31 December 2019).

Special Issue Editor

Dr. Inka Manek-Hönninger
Website
Guest Editor
Centre Lasers Intenses et Applications (CELIA) – UMR5107
University of Bordeaux
33405 Talence Cedex
France
Interests: laser crystals; laser-matter interaction; optical material characterization; direct laser writing (DLW); waveguides; surface texturing with ultrafast lasers

Special Issue Information

Dear Colleagues,

Crystalline materials as active media are nowadays widely used in both, scientific and industrial laser sources and amplifier systems for a large variety of applications, including machining and micromachining of materials, medical surgery, security and defense, entertainment, and fundamental research. Thanks to their specific properties, arising from the host and active ion doping, laser crystals can respond to many different demands in terms of wavelength, output power and energy, and continuous wave or pulsed laser operation.

Research activities in the fields of new crystalline host matrices, doping and co-doping with different active ions, crystal structure and effects of laser crystals under polarized light are investigated. Exciting studies are carried out on power scaling, short-pulse generation and the research to access to new wavelengths.

The purpose of this Special Issue of Crystals dedicated to laser crystals is to collect papers either giving an overview of the state-of-the-art or reporting on recent advances in the study of laser crystals including, but not limited to, the topics mentioned below in the keyword list. Scientists and engineers working in the fields of laser crystals and their applications are cordially invited to contribute to this Special Issue.

Dr. Inka Manek-Hönninger
Guest Editor

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. Crystals is an international peer-reviewed open access monthly 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 1800 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

  • Laser crystals
  • New host matrices
  • Doping and co-doping
  • Crystal growth
  • Crystal characterization of optical properties
  • Polarization effects
  • Laser performances
  • New wavelengths
  • Short-pulse generation
  • Laser power scaling

Published Papers (6 papers)

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Research

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Open AccessArticle
Double-Track Waveguides inside Calcium Fluoride Crystals
Crystals 2020, 10(2), 109; https://doi.org/10.3390/cryst10020109 - 12 Feb 2020
Abstract
Calcium Fluoride (CaF2) was selected owing to its cubic symmetry and excellent luminescence properties as a crystal of interest, and ultrafast laser inscription of in-bulk double-track waveguides was realized. The guiding properties of these waveguides in relation to the writing energy [...] Read more.
Calcium Fluoride (CaF2) was selected owing to its cubic symmetry and excellent luminescence properties as a crystal of interest, and ultrafast laser inscription of in-bulk double-track waveguides was realized. The guiding properties of these waveguides in relation to the writing energy of the femtosecond pulse are presented. The modified double-track waveguides have been studied by systematic developments of beam propagation experiments and numerical simulations. Furthermore, an adapted model and concepts were engaged for the quantitative and qualitative characterization of the waveguides, particularly for the transmission loss measurements and the three-dimensional refractive index mappings of the modified zones. Additionally, polarization-dependent guiding was investigated. Full article
(This article belongs to the Special Issue Laser Crystals)
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Open AccessArticle
Pulse-Propagation Modeling and Experiment for Femtosecond-Laser Writing of Waveguide in Nd:YAG
Crystals 2019, 9(8), 434; https://doi.org/10.3390/cryst9080434 - 20 Aug 2019
Cited by 8
Abstract
In this work, unidirectional pulse propagation equation (UPPE) modeling is performed to study the nonlinear laser-mater interaction in silicon and Nd:Y3Al5O12 (Nd:YAG) crystals. The simulation results are validated with reported experimental results for silicon and applied to Nd:YAG [...] Read more.
In this work, unidirectional pulse propagation equation (UPPE) modeling is performed to study the nonlinear laser-mater interaction in silicon and Nd:Y3Al5O12 (Nd:YAG) crystals. The simulation results are validated with reported experimental results for silicon and applied to Nd:YAG crystals with experimental validation. Stress-induced waveguides are written in Nd:YAG crystals using 515 nm, 300 fs pulses at a 1 kHz repetition rate. Waveguides having a mean propagation loss of 0.21 ± 0.06 dB/cm are obtained, which is lower than the previous reported values for Type-II waveguides written in Nd:YAG crystals. The modeling and experimental results consistently show that the modification (waveguide track) depth increases with input energy. A detailed analysis is presented to control the modal properties of the waveguide in the context of UPPE simulation. Full article
(This article belongs to the Special Issue Laser Crystals)
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Open AccessArticle
Direct Amplification of High Energy Pulsed Laser in Fiber-Single Crystal Fiber with High Average Power
Crystals 2019, 9(4), 216; https://doi.org/10.3390/cryst9040216 - 21 Apr 2019
Cited by 2
Abstract
A laser master oscillator power amplifier (MOPA) system consisting of a fiber amplifier and a two-stage Yb:YAG single crystal fiber (SCF) is experimentally studied. The nonlinear stimulated Raman scattering (SRS) is avoided by limiting the output power of the fiber preamplifier to 600 [...] Read more.
A laser master oscillator power amplifier (MOPA) system consisting of a fiber amplifier and a two-stage Yb:YAG single crystal fiber (SCF) is experimentally studied. The nonlinear stimulated Raman scattering (SRS) is avoided by limiting the output power of the fiber preamplifier to 600 mW. Due to the benefit from the low nonlinearity and high amplification gain of the SCF, a laser pulse duration of 16.95 ps and a high average power of 41.7 W at a repetition rate of 250 kHz are obtained by using a two-stage polarization controlled double-pass amplification of Yb:YAG SCF, corresponding to an output energy of 166.8 μJ and a peak power of 9.84 MW, respectively. The polarization controlled SCF amplification scheme achieved a gain as high as more than 69 times. During the amplification, the spectra gain narrowing effect and the polarization controlled four-pass amplification setup are also studied. The laser spectrum is narrowed from over 10 nm to less than 3 nm, and the pulse width is also compressed to hundreds of femtosecond by dechirping the laser pulse. This compact-sized, cost-effective laser source can be used in laser micromachining, or as the seeder source for generating much higher power and energy laser for scientific research. For some applications which need femtosecond laser, this laser source can also be compressed to femtosecond regime. Full article
(This article belongs to the Special Issue Laser Crystals)
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Open AccessArticle
New Sellmeier and Thermo-Optic Dispersion Formulas for AgGaS2
Crystals 2019, 9(3), 129; https://doi.org/10.3390/cryst9030129 - 04 Mar 2019
Cited by 1
Abstract
This paper reports on the new Sellmeier and thermo-optic dispersion formulas that provide a good reproduction of the temperature-dependent phase-matching conditions for second-harmonic generation (SHG) and sum-frequency generation (SFG) of a CO2 laser and a Nd:YAG laser-pumped KTiOPO4 (KTP) optical parametric [...] Read more.
This paper reports on the new Sellmeier and thermo-optic dispersion formulas that provide a good reproduction of the temperature-dependent phase-matching conditions for second-harmonic generation (SHG) and sum-frequency generation (SFG) of a CO2 laser and a Nd:YAG laser-pumped KTiOPO4 (KTP) optical parametric oscillator (OPO) in the 0.8859–10.5910 μm range as well as those for difference-frequency generation (DFG) between the two diode lasers in the 4.9–6.5 μm range and DFG between the two periodically poled LiNbO3 (PPLN) OPOs in the 5–12 μm range thus far reported in the literature. Full article
(This article belongs to the Special Issue Laser Crystals)
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Review

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Open AccessReview
Femtosecond Laser Pulses Amplification in Crystals
Crystals 2019, 9(7), 347; https://doi.org/10.3390/cryst9070347 - 05 Jul 2019
Abstract
This paper describes techniques for high-energy laser pulse amplification in multi-PW femtosecond laser pulses. Femtosecond laser pulses can be generated and amplified in laser media with a broad emission spectral bandwidth, like Ti:sapphire crystals. By chirped pulse amplification (CPA) techniques, hundred-Joule amplified laser [...] Read more.
This paper describes techniques for high-energy laser pulse amplification in multi-PW femtosecond laser pulses. Femtosecond laser pulses can be generated and amplified in laser media with a broad emission spectral bandwidth, like Ti:sapphire crystals. By chirped pulse amplification (CPA) techniques, hundred-Joule amplified laser pulses can be obtained. Multi-PW peak-power femtosecond pulses are generated after recompression of amplified chirped laser pulses. The characteristics and problems of large bandwidth laser pulses amplification in Ti:sapphire crystals are discussed. An alternative technique, based on optical parametric chirped pulse amplification (OPCPA) in nonlinear crystals, is presented. Phase-matching conditions for broad bandwidth parametric amplification in nonlinear crystals are inferred. Ultra-broad phase matching bandwidth of more than 100 nm, able to support the amplification of sub-10 fs laser pulses, are demonstrated in nonlinear crystals, such as Beta Barium Borate (BBO), Potassium Dideuterium Phosphate (DKDP), and Lithium Triborate (LBO). The advantages and drawbacks of CPA amplification in laser crystals and OPCPA in nonlinear crystals are discussed. A hybrid amplification method, which combines low-medium energy OPCPA in nonlinear crystals with high energy CPA in large aperture laser crystals, is described. This technique is currently used for the development of 10-PW laser systems, with sub-20 fs pulse duration and more than 1012 intensity contrast of output femtosecond pulses. Full article
(This article belongs to the Special Issue Laser Crystals)
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Open AccessReview
Laser Performance of Neodymium- and Erbium-Doped GYSGG Crystals
Crystals 2019, 9(4), 220; https://doi.org/10.3390/cryst9040220 - 24 Apr 2019
Abstract
Garnet crystals possess many properties that are desirable in laser host materials, e.g., they are suitable for diode laser (LD) pumping, stable, hard, optically isotropic, and have good thermal conductivity, permitting laser operation at high average power levels. Recently, a new garnet material, [...] Read more.
Garnet crystals possess many properties that are desirable in laser host materials, e.g., they are suitable for diode laser (LD) pumping, stable, hard, optically isotropic, and have good thermal conductivity, permitting laser operation at high average power levels. Recently, a new garnet material, GYSGG, was developed by replacing some of the yttrium ions (Y3+) with gadolinium ions (Gd3+) in YSGG, demonstrating great potential as a laser host material. GYSGG crystals doped with trivalent neodymium ion (Nd3+) and erbium ions (Er3+) were successfully grown for laser generation in the near- and mid-infrared range, with some of the laser performances reaching the level of mature laser gain media. This paper gives an overview of the achievements made in Nd3+- and Er3+-doped GYSGG lasers at different wavelength ranges. Additionally, full descriptions on Q-switching, mode-locking and wavelength-selecting methods for Nd:GYSGG, and the mechanisms of power scaling by co-doping sensitizers and deactivators in Er:GYSGG, are given. It is expected that this review will help researchers from related areas to quickly gain an understanding of these laser materials and promotes their commercialization and applications. Full article
(This article belongs to the Special Issue Laser Crystals)
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