Ultrafast Laser Systems

A special issue of Photonics (ISSN 2304-6732). This special issue belongs to the section "Lasers, Light Sources and Sensors".

Deadline for manuscript submissions: closed (15 January 2024) | Viewed by 14611

Special Issue Editors


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Guest Editor
School of Physics and Optoelectronic Engineering, Xidian University, Xi’an 710071, China
Interests: solid-state lasers; femtosecond lasers; laser amplification; nonlinear frequency conversion; laser micro-fabrication

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Guest Editor
School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
Interests: thin-disk lasers; mode-locked lasers; high-power lasers; mid-infrared lasers
School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
Interests: mid-infrared lasers; mode-locked lasers; ultrafast nonlinear optics

Special Issue Information

Dear Colleagues,

Over the past few decades, ultrafast lasers have been studied intensively and have become indispensable tools for diverse applications in physics, biology, chemistry, medicine, and industry. Now, the pulse duration of ultrafast laser systems has been shortened from the traditional picosecond and femtosecond range down to the attosecond level; the peak power has reached 10 PW based on chirped-pulse amplification technology; and the spectrum can cover wavelengths from extreme ultraviolet to terahertz. These achievements enrich the understanding of scientists in regard to the principles of ultrafast laser, while paving the way for the invention of new technologies in many fields. However, the development of ultrafast lasers is far from an end, as properties such as a higher average power and pulse energy, shorter pulse duration, broader spectrum bandwidth, new wavelengths, higher stability and compact size are becoming more and more desirable.

This Special Issue focuses on the latest progress in the development of ultrafast laser systems. In this Special Issue, original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

  • Mode-locking technique;
  • Femtosecond solid-state lasers;
  • Femtosecond fiber lasers;
  • Ultrafast laser amplifiers;
  • Ultrafast nonlinear techniques;
  • Ultrafast EUV/MIR/THz techniques;
  • Attosecond laser technologies;
  • Frequency combs;
  • Ultrafast laser materials;
  • Ultrafast laser applications.

We look forward to receiving your contributions.

Prof. Dr. Jiangfeng Zhu
Prof. Dr. Jinwei Zhang
Dr. Qing Wang
Guest Editors

Manuscript Submission Information

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Keywords

  • femtosecond laser
  • mode-locked laser
  • laser amplifier
  • attosecond
  • nonlinear frequency conversion
  • ultrafast dynamics
  • novel laser material

Published Papers (10 papers)

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Research

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8 pages, 1533 KiB  
Article
Watt-Level Diode-End-Pumped Self-Mode-Locked Tm,Ho:LLF Laser
by Su Zhang, Liheng Ma, Wen Liu, Chunsheng Sun, Hongwei Han, Qingping Hu, Shuang Zhang and Li Kai
Photonics 2023, 10(10), 1133; https://doi.org/10.3390/photonics10101133 - 10 Oct 2023
Viewed by 682
Abstract
A diode-end-pumped self-mode-locked Tm,Ho:LuLiF4 (LLF) laser is demonstrated for the first time, to the best of our knowledge. At the incident pump power of 3.4 W, the stable self-mode-locked operation of the Tm,Ho:LLF laser was realized without any additional devices in the [...] Read more.
A diode-end-pumped self-mode-locked Tm,Ho:LuLiF4 (LLF) laser is demonstrated for the first time, to the best of our knowledge. At the incident pump power of 3.4 W, the stable self-mode-locked operation of the Tm,Ho:LLF laser was realized without any additional devices in the resonator. Further increasing the incident pump power to 6.8 W, the maximum average output power of 1.07 W was achieved at 2068 nm with a pulse width of 746 ps and a repetition frequency of 468 MHz. The experimental results indicate that the Tm,Ho:LLF crystal is promising to generate the high-power self-mode-locked solid-state laser at 2 μm waveband. The self-mode-locked Tm,Ho:LLF laser has potential applications in optical communication, remote sensing, material process, and nonlinear frequency conversion. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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11 pages, 3292 KiB  
Article
Ultrafast Fiber Laser Emitting at 2.8 µm Based on a SESAM and a Broadband FBG
by Pascal Paradis, Tommy Boilard, Vincent Fortin, Réal Vallée and Martin Bernier
Photonics 2023, 10(7), 753; https://doi.org/10.3390/photonics10070753 - 29 Jun 2023
Viewed by 1055
Abstract
Ultrafast mid-infrared fiber lasers have been intensely studied in the last decade for the generation of high harmonics, molecular spectroscopy, material processing and remote sensing. Different designs have been investigated but most of them lacked the ease of use and reliability needed for [...] Read more.
Ultrafast mid-infrared fiber lasers have been intensely studied in the last decade for the generation of high harmonics, molecular spectroscopy, material processing and remote sensing. Different designs have been investigated but most of them lacked the ease of use and reliability needed for their democratization. In this paper, we demonstrate a self-starting mode-locked mid-IR erbium-doped fiber laser based on a SESAM and a broadband uniform FBG that produces pulses as short as 15 ps. Different laser cavities were tested with varying FBG peak reflectance, spectral bandwidth and active fiber length. In addition, one cavity uses a pump combiner instead of injecting free-space the pump power through the fiber tip. The results of this study confirm that the FBG spectral bandwidth can efficiently control the duration of the almost Fourier-transform-limited pulses up to a limit seemingly dictated by the presence of water vapor in the laser cavity acting as narrow spectral filters. To a lower effect, the active fiber length influences the pulse duration. Finally, the use of an all-fiber pump combiner allows for a more compact and rugged design without altering the laser performances. This study represents a step towards the development of robust mid-infrared ultrafast all-fiber lasers. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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11 pages, 6388 KiB  
Article
The Spatiotemporal Dynamics of Electron Plasma in Femtosecond Laser Double Pulses Induced Damage in Fused Silica
by Tianlun Shen, Jinhai Si, Dongpo Tian, Tao Chen, Peng Li and Xun Hou
Photonics 2023, 10(6), 702; https://doi.org/10.3390/photonics10060702 - 20 Jun 2023
Cited by 2 | Viewed by 1006
Abstract
In this study, we employed the fs time-resolved shadowgraphy method to investigate the impact of the first pump pulse (DP1) on the transient temporal and spatial evolution of electron plasma induced by femtosecond (fs) laser double pulses (DPs) in fused silica. It was [...] Read more.
In this study, we employed the fs time-resolved shadowgraphy method to investigate the impact of the first pump pulse (DP1) on the transient temporal and spatial evolution of electron plasma induced by femtosecond (fs) laser double pulses (DPs) in fused silica. It was observed that the DP1-induced phase transition acted as a waveguide, confining the propagation of the second pump pulse (DP2) light inside the material and resulting in a decrease in the diameter of the DP2-induced electron plasma region. Moreover, the DP2-induced maximum peak electron density was higher than that induced by a single pulse (SP) at the same pulse energy, which may be explained by the DP1-induced highly absorbing semi-metallic state of warm dense glass in fused silica. Importantly, as the energy of DP1 increased, the mean diameter of the DP2-induced electron plasma region further decreased, and the maximum peak electron density increased. Compared with SPs, DPs more easily produced damage in fused silica. In addition, the mean diameter of the DP2-induced electron plasma region and the maximum peak electron density remained almost unchanged when the pulses’ time separation (ts) was changed from 1 to 50 ps, mainly due to the long relaxation time of the phase transition caused by DP1. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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9 pages, 3397 KiB  
Communication
All-Polarization-Maintaining, Mode-Locking Fiber Front-End Laser Delivering Both the Picosecond Seed Laser and the Femtosecond Seed Laser
by Yinuo Zhang, Hao Zhang, Kong Gao, Wenchao Qiao, Tianli Feng, Xian Zhao and Yizhou Liu
Photonics 2023, 10(6), 665; https://doi.org/10.3390/photonics10060665 - 08 Jun 2023
Viewed by 1101
Abstract
An ytterbium-doped, mode-locking fiber front-end laser, delivering both a femtosecond seed laser and picosecond seed laser, was demonstrated. The fundamental repetition rate of the 1031 nm mode-locked laser was 32.77 MHz, realized with the all-polarization-maintaining (all-PM) nonlinear amplifying loop mirror (NALM). The femtosecond [...] Read more.
An ytterbium-doped, mode-locking fiber front-end laser, delivering both a femtosecond seed laser and picosecond seed laser, was demonstrated. The fundamental repetition rate of the 1031 nm mode-locked laser was 32.77 MHz, realized with the all-polarization-maintaining (all-PM) nonlinear amplifying loop mirror (NALM). The femtosecond seed laser and the picosecond seed laser were delivered after carefully optimizing the nonlinear amplification process. The corresponding pulse durations were 85 fs and 2.88 ps, with average power of 171 mW and 562.5 mW, respectively. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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8 pages, 3084 KiB  
Communication
High–Efficiency, Widely Tunable MgO: PPLN Optical Parametric Oscillator
by Yueyue Lian, Wenlong Tian, Hao Sun, Yang Yu, Yulong Su, Hui Tong, Jiangfeng Zhu and Zhiyi Wei
Photonics 2023, 10(5), 505; https://doi.org/10.3390/photonics10050505 - 27 Apr 2023
Cited by 1 | Viewed by 1407
Abstract
We report on the investigation of a high–efficiency, widely tunable femtosecond optical parametric oscillator (OPO) based on a multi–period MgO–doped periodically poled lithium niobite (MgO: PPLN) crystal, pumped by an all–solid–state femtosecond mode–locked Yb: KGW laser at 1030 nm providing 100 fs pulses. [...] Read more.
We report on the investigation of a high–efficiency, widely tunable femtosecond optical parametric oscillator (OPO) based on a multi–period MgO–doped periodically poled lithium niobite (MgO: PPLN) crystal, pumped by an all–solid–state femtosecond mode–locked Yb: KGW laser at 1030 nm providing 100 fs pulses. With 6 W pump power, the OPO generates 2.68 W of signal power at 1540 nm and 1.2 W of idler power at 3110 nm, which corresponds to the total conversion efficiency adding up to 67.4%. To the best of our knowledge, this is the highest conversion efficiency of a femtosecond OPO. Meanwhile, in order to obtain a broad optical spectrum range, both the grating period and working temperature are tuned, resulting in tunable signals of 1.43–1.78 µm and idlers of 2.44–3.68 µm. This source will be used to generate a femtosecond mid–infrared laser of wavelength range 3.7–6.5 µm and tens milliwatts average power through difference frequency generation (DFG). Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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8 pages, 3641 KiB  
Article
Dynamics of the Femtosecond Mid-IR Laser Pulse Impact on a Bulk Silicon
by Evgenii Mareev, Nikolay Obydennov and Fedor Potemkin
Photonics 2023, 10(4), 380; https://doi.org/10.3390/photonics10040380 - 30 Mar 2023
Cited by 1 | Viewed by 1280
Abstract
In this study, we reconstructed the dynamics of the impact of mid-IR-range (4.6 μm) femtosecond laser pulses on bulk silicon under tight focusing conditions (NA = 0.5). Our experimental results show that under this impact, the deposited energy density (DED) reaches approximately 4 [...] Read more.
In this study, we reconstructed the dynamics of the impact of mid-IR-range (4.6 μm) femtosecond laser pulses on bulk silicon under tight focusing conditions (NA = 0.5). Our experimental results show that under this impact, the deposited energy density (DED) reaches approximately 4 kJ/cm3 (at an energy slightly above the plasma-formation threshold). Initially, the femtosecond pulse energy is absorbed by the laser-induced plasma, with a lifetime of approximately 160–320 fs (depending on the laser pulse energy). The energy transfer from the plasma to the atomic subsystem occurs on a sub-ps timescale, which generates a shock wave and excites coherent phonons on a sub-ps scale. The shift of atoms in the lattice at the front of the shock wave results in a cascade of phase transitions (Si-X => Si-VII => Si-VI => Si-XI => Si-II), leading to a change in the phonon spectra of silicon. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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10 pages, 483 KiB  
Communication
Inverse Saturable Absorption Mechanism in Mode-Locked Fiber Lasers with a Nonlinear Amplifying Loop Mirror
by Xiang Zhang, Yong Shen, Xiaokang Tang, Qu Liu and Hongxin Zou
Photonics 2023, 10(3), 261; https://doi.org/10.3390/photonics10030261 - 01 Mar 2023
Cited by 3 | Viewed by 2068
Abstract
From the perspective of the differential phase delay experienced by the two counterpropagating optical fields, the self-starting of the mode-locked fiber laser with a non-linear amplifying loop mirror (NALM) is theoretically studied. Although it is generally believed that NALM shows a saturable absorption [...] Read more.
From the perspective of the differential phase delay experienced by the two counterpropagating optical fields, the self-starting of the mode-locked fiber laser with a non-linear amplifying loop mirror (NALM) is theoretically studied. Although it is generally believed that NALM shows a saturable absorption effect on both continuous wave (CW) light and pulses, we find a counter-intuitive fact that cross-phase modulation (XPM) leads to opposite signs of differential non-linear phase shifts (NPSs) in these two cases, resulting in inverse saturable absorption (ISA) during the pulse formation process. The ISA is not helpful for the self-starting of laser mode-locking and can be alleviated by introducing a non-reciprocal phase shifter into the fiber loop. These results are helpful for optimizing the design of NALM and lowering the self-starting threshold of the high-repetition-rate mode-locked fiber laser. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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7 pages, 1465 KiB  
Communication
Generation of 48 fs, 1 GHz Fundamentally Mode-Locked Pulses Directly from an Yb-doped “Solid-State Fiber Laser”
by Mengyun Hu, Jiawei Shen, Yuzhi Cao, Shuai Yuan and Heping Zeng
Photonics 2023, 10(2), 192; https://doi.org/10.3390/photonics10020192 - 11 Feb 2023
Viewed by 1613
Abstract
We demonstrate a fundamentally mode-locked Yb-doped “solid-state fiber laser” with a repetition rate of 1 GHz and a pulse duration of 48 fs. The nonlinear-polarization-evolution (NPE) mode-locking of the “solid-state fiber laser” enables up to 286 mW of average power and a 26 [...] Read more.
We demonstrate a fundamentally mode-locked Yb-doped “solid-state fiber laser” with a repetition rate of 1 GHz and a pulse duration of 48 fs. The nonlinear-polarization-evolution (NPE) mode-locking of the “solid-state fiber laser” enables up to 286 mW of average power and a 26 nm spectrum bandwidth, which supports a 48 fs pulse duration. The laser self-starts and the central wavelength can be tuned from 1032.4 nm to 1035.6 nm. To the best of our knowledge, it is the shortest pulse duration directly obtained by GHz fundamentally mode-locked Yb-fiber lasers. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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11 pages, 1573 KiB  
Article
Observation of Wavelength Tuning in a Mode-Locked Figure-9 Fiber Laser
by Han Zhang, Handing Xia, Mengqiu Fan, Junwen Zheng, Jianbin Li, Xiaocheng Tian, Dandan Zhou, Zhimeng Huang, Fan Zhang, Rui Zhang, Zhitao Peng and Qihua Zhu
Photonics 2023, 10(2), 184; https://doi.org/10.3390/photonics10020184 - 08 Feb 2023
Cited by 2 | Viewed by 2120
Abstract
We demonstrate an all-PM Er-doped soliton mode-locked fiber oscillator based on the figure-9 configuration with a compact adjustable reflection-type non-reciprocal phase shifter. An analytical model based on the Jones matrix is established to simulate the wavelength tuning phenomenon. Experimentally, it is observed that [...] Read more.
We demonstrate an all-PM Er-doped soliton mode-locked fiber oscillator based on the figure-9 configuration with a compact adjustable reflection-type non-reciprocal phase shifter. An analytical model based on the Jones matrix is established to simulate the wavelength tuning phenomenon. Experimentally, it is observed that the increase in pump power results in a significant redshift in the spectrum of output pulses. When the angle of the half-wave plate is rotated in one direction, the output spectrum is redshifted and then blueshifted successively. Good qualitative agreement is presented between the simulations and the experimental results. It is shown that the increase in pump power changes the nonlinear phase shift, which causes the redshift of the transmittance curves at the laser output port. In contrast, the rotation of wave plates not only changes the nonlinear phase shift difference, but also causes variations in linear phase bias and modulation depth. The changes in these parameters lead to the redshift and blueshift of the transmission curves, which enables wavelength tuning. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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Review

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25 pages, 32156 KiB  
Review
Modification of Diamond Surface by Femtosecond Laser Pulses
by Vitali V. Kononenko
Photonics 2023, 10(10), 1077; https://doi.org/10.3390/photonics10101077 - 25 Sep 2023
Viewed by 1285
Abstract
The basic mechanisms of laser interaction with synthetic diamond are reviewed. The characteristics of the main regimes of diamond surface etching are considered. In addition to the well-known graphitization and ablation processes, nanoablation and accumulative graphitization, which have attracted relatively recent attention, are [...] Read more.
The basic mechanisms of laser interaction with synthetic diamond are reviewed. The characteristics of the main regimes of diamond surface etching are considered. In addition to the well-known graphitization and ablation processes, nanoablation and accumulative graphitization, which have attracted relatively recent attention, are described in detail. The focus is on femtosecond (fs) laser exposure, which allows for the formation of a dense cold electron–hole plasma in the focal zone and minimal overheating in the surrounding area. This potentially opens the way to the development of unique laser-based technologies that combine physical and chemical processes for precise surface treatment and functionalization. The physical limitations that determine how precisely the diamond surface can be treated by short-pulsed laser radiation and possible ways to overcome them with the ultimate goal of removing ultrathin layers of the material are discussed. Special attention is paid to the novel possibility of inducing the local formation of point active defects—nitrogen vacancy (NV) complexes in the laser-irradiated zone. Such defects have been at the forefront of solid-state physics for the past thirty years due to continuous attempts to exploit their unique properties in quantum optics, quantum computing, magnetometry, probing, and other fields. Both regimes of NV center formation with and without graphitization of the diamond lattice are considered. Thus, it is shown that intense pulsed laser irradiation is a perfect tool for the processing of synthetic diamonds at the micro-, nano-, and even at the atomic level, which can be well controlled and managed. Full article
(This article belongs to the Special Issue Ultrafast Laser Systems)
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