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2 pages, 158 KiB

Open AccessEditorial

Special Issue on Fiber Laser and Their Applications

by Song Yang, Ling Zhang, Zhiwei Zhu and Li Li

Photonics 2023, 10(10), 1149; https://doi.org/10.3390/photonics10101149 - 12 Oct 2023

Viewed by 797

Abstract

Fiber lasers have achieved significant advancements owing to their compactness, perfect beam quality, good environmental adaptability, and so on [...] Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

Research

Jump to: Editorial

12 pages, 2978 KiB

Open AccessArticle

An Ytterbium-Doped Narrow-Bandwidth Randomly Distributed Feedback Laser Emitting at a Wavelength of 976 nm

by Danila A. Davydov, Andrey A. Rybaltovsky, Svetlana S. Aleshkina, Vladimir V. Velmiskin, Mikhail E. Likhachev, Sergei M. Popov, Dmitry V. Ryakhovskiy, Yuriy K. Chamorovskiy, Andrey A. Umnikov and Denis S. Lipatov

Photonics 2023, 10(8), 951; https://doi.org/10.3390/photonics10080951 - 19 Aug 2023

Cited by 1 | Viewed by 1042

Abstract

All-fiber, polarization maintaining, narrow-bandwidth, Yb-doped fiber lasers with randomly distributed feedback operated near 976 nm were realized for the first time. It was shown that the laser operated in a single, longitudinal mode regime during intervals of a few seconds. At other times, [...] Read more.

All-fiber, polarization maintaining, narrow-bandwidth, Yb-doped fiber lasers with randomly distributed feedback operated near 976 nm were realized for the first time. It was shown that the laser operated in a single, longitudinal mode regime during intervals of a few seconds. At other times, the laser generated a few longitudinal modes, but its bandwidth was always below the resolution of the optical spectrum analyzer (0.02 nm). The linewidth of each single longitudinal mode of the laser was estimated to be below 20 kHz. The reasons for this observed laser behavior were discussed and methods for achieving stable, continuous wave operation in the single-longitudinal-mode regime were proposed. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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10 pages, 4068 KiB

Open AccessEditor’s ChoiceCommunication

Effect of Contact Angle on Friction Properties of Superhydrophobic Nickel Surface

by Junyuan Huang, Zhiwei Zhu, Ling Zhang, Dongdong Guo, Zhen Niu and Wei Zhang

Photonics 2023, 10(7), 829; https://doi.org/10.3390/photonics10070829 - 17 Jul 2023

Cited by 2 | Viewed by 1061

Abstract

Due to their excellent performance, superhydrophobic materials have received a lot of attention and research in friction reduction and wear resistance. However, the effect of different contact angles of superhydrophobicity on friction and wear properties has not been thoroughly studied. In this paper, [...] Read more.

Due to their excellent performance, superhydrophobic materials have received a lot of attention and research in friction reduction and wear resistance. However, the effect of different contact angles of superhydrophobicity on friction and wear properties has not been thoroughly studied. In this paper, a nanosecond pulsed laser was used to realize the preparation of a superhydrophobic nickel surface, which indeed reduced the coefficient of friction but also increased the wear volume when compared to the unprocessed surface. As the contact angle of the superhydrophobic nickel surface increased, the coefficient of friction gradually increased, and the wear volume decreased gradually in superhydrophobic nickel surfaces. When the laser energy density was 1 J/cm², the contact angle was 150.3° and the minimum friction coefficient was 0.4. However, when the laser energy density was 50 J/cm², the maximum contact angle was 156.4° and the minimum wear volume was 4.23 × 10⁷ μm³. The friction direction also influenced the tribological properties of the superhydrophobic-textured surface. This method makes it possible to process superhydrophobic surfaces with more suitable friction and wear properties. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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13 pages, 3236 KiB

Open AccessArticle

High Efficient Random Laser with Cavity Based on the Erbium-Doped Germanophosphosilicate Artificial Rayleigh Fiber

by Sergei Popov, Andrey Rybaltovsky, Alexei Bazakutsa, Alexander Smirnov, Dmitry Ryakhovskiy, Viktor Voloshin, Alexander Kolosovskii, Igor Vorob’ev, Viktor Isaev, Yuriy Chamorovskiy, Denis Lipatov and Oleg Butov

Photonics 2023, 10(7), 748; https://doi.org/10.3390/photonics10070748 - 28 Jun 2023

Cited by 2 | Viewed by 873

Abstract

The Erbium “random” laser, based on the artificial Rayleigh fiber, has been comparatively studied in detail under two different pump conditions: 974.5 and 1485 nm pumping wavelengths. The artificial Rayleigh 7-m-long fiber was used as a laser cavity, it was formed by the [...] Read more.

The Erbium “random” laser, based on the artificial Rayleigh fiber, has been comparatively studied in detail under two different pump conditions: 974.5 and 1485 nm pumping wavelengths. The artificial Rayleigh 7-m-long fiber was used as a laser cavity, it was formed by the ultraviolet (UV) inscription of the uniform array of the weakly reflective fiber Bragg grating (FBG) during the fiber drawing process. The UV photosensitivity of the Erbium-doped fiber originated from the specially developed (germanophosphosilicate) core glass composition. The emission spectrum of the fabricated “random” fiber laser had a single narrow peak at the 1548 nm wavelength. It was clearly revealed that the extension of the laser cavity by the separate wavelength-matched 90%-reflective FBG resulted in a significant laser efficiency growth. The highest laser slope efficiency of 33% and the laser output power of 80 mW were reached in the FBG-modified cavity at the 974.5-nm-wavelength pumping. The continuous-wave operation mode of this laser has been confirmed. The laser linewidth value measured by the delayed self-heterodyne technique was about 550 Hz. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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11 pages, 3059 KiB

Open AccessCommunication

Relocking and Locking Range Extension of Partially Locked AMLL Cavity Modes with Two Detuned RF Sinusoids

by Shree Krishnamoorthy and Anil Prabhakar

Photonics 2023, 10(7), 735; https://doi.org/10.3390/photonics10070735 - 27 Jun 2023

Cited by 1 | Viewed by 708

Abstract

Actively mode-locked fiber ring lasers (AMLLs) with loss modulators are used to generate approximately

100 ps

pulses with

100 MHz

repetition. RF detuning around the fundamental frequency,

f_{0}

, causes a loss in phase lock (unlocking) of cavity modes and partial mode [...] Read more.

Actively mode-locked fiber ring lasers (AMLLs) with loss modulators are used to generate approximately

100 ps

pulses with

100 MHz

repetition. RF detuning around the fundamental frequency,

f_{0}

, causes a loss in phase lock (unlocking) of cavity modes and partial mode locking. Multiple RF inputs are shown, theoretically, to relock and extend the locking range of cavity modes in a detuned partially mode-locked AMLL. A custom-built Yb

^{3 +}

-doped AMLL with

f_{0} = 26 MHz

, and operating wavelength of

1064 nm

, was used to experimentally verify the theoretical predictions. Two RF sinusoidal signals with constant phase and equal amplitude resulted in an extension of the range by

X_{n} = 6.4 kHz

in addition to the range

R_{n} = 14.34 kHz

with single input for the mode

n = 10

. An increase in locking range was also observed for higher modes. Pulsewidth reduction to approximately

205 ps

from about

2 ns

was also observed in the AMLL. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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11 pages, 4313 KiB

Open AccessArticle

Characterization of Grid Lines Formed by Laser-Induced Forward Transfer and Effect of Laser Fluence on the Silver Paste Transformation

by Yucui Yu, Yanmei Zhang, Chongxin Tian, Xiuli He, Shaoxia Li and Gang Yu

Photonics 2023, 10(7), 717; https://doi.org/10.3390/photonics10070717 - 22 Jun 2023

Cited by 1 | Viewed by 1116

Abstract

The investigation of novel approaches for forming solar cell grid lines has gained importance with the rapid development of the photovoltaic industry. Laser-induced forward transfer (LIFT) is a very promising approach for microstructure fabrication. In this work, the morphology of grid lines deposited [...] Read more.

The investigation of novel approaches for forming solar cell grid lines has gained importance with the rapid development of the photovoltaic industry. Laser-induced forward transfer (LIFT) is a very promising approach for microstructure fabrication. In this work, the morphology of grid lines deposited by LIFT was investigated. A characterization scheme for solar cell grid lines was proposed. The shape of grid lines was described, combined with confocal imaging. The evolution process of grid lines from no forming to single-peak and double-peak with a variation of laser fluence was observed. According to experimental conditions, different types of grid line morphology were obtained and transfer mechanisms of silver paste were proposed based on fluid dynamics. The influence of laser fluence on the morphology of formed grid lines was explained through phenomenology and analysis. This can provide a guide for morphology control in forming the process of grid lines. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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14 pages, 6639 KiB

Open AccessArticle

Numerical Simulation of High-Power Optical Amplifiers at 2.3 µm Based on a Special Multicore Fiber

by Elena A. Anashkina, Alexey V. Andrianov and Alexander G. Litvak

Photonics 2023, 10(7), 711; https://doi.org/10.3390/photonics10070711 - 21 Jun 2023

Cited by 1 | Viewed by 707

Abstract

The development of high-power laser sources at 2.3 µm is highly demanded for remote sensing and other applications. However, this wavelength is poorly covered by present-day lasers. To obtain 100 W class high-power radiation at 2.3 μm, we propose to use simultaneously cascade [...] Read more.

The development of high-power laser sources at 2.3 µm is highly demanded for remote sensing and other applications. However, this wavelength is poorly covered by present-day lasers. To obtain 100 W class high-power radiation at 2.3 μm, we propose to use simultaneously cascade laser amplification at 2 and 2.3 µm with a commercially available diode pump at 793 nm and stimulated Raman scattering between the amplified signal waves in a special zinc–tellurite multicore fiber with ten trivalent-thulium-ion-doped cores arranged in a ring. We demonstrate numerically that the use of an out-of-phase supermode (with spatial phases differing by π in neighboring cores) can provide up to 50% efficiency conversion from the 793 nm pump to the 2.3 µm wave. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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7 pages, 1304 KiB

Open AccessCommunication

Distributed Bragg Reflector Laser Based on Composite Fiber Heavily Doped with Erbium Ions

by Mikhail I. Skvortsov, Kseniya V. Proskurina, Evgeniy V. Golikov, Alexander V. Dostovalov, Vadim S. Terentyev, Olga N. Egorova, Sergey L. Semjonov and Sergey A. Babin

Photonics 2023, 10(6), 679; https://doi.org/10.3390/photonics10060679 - 12 Jun 2023

Cited by 2 | Viewed by 1146

Abstract

A distributed Bragg reflector (DBR) laser with a specially designed, heavily Er³⁺-doped composite fiber of a length as short as 1.8 cm is demonstrated. The DBR laser, pumped by a 980 nm laser diode with power of up to 370 mW, [...] Read more.

A distributed Bragg reflector (DBR) laser with a specially designed, heavily Er³⁺-doped composite fiber of a length as short as 1.8 cm is demonstrated. The DBR laser, pumped by a 980 nm laser diode with power of up to 370 mW, generates single-frequency radiation at a wavelength of 1535 nm with a narrow instantaneous linewidth of <100 Hz and a high output power of 2 mW. The obtained Er³⁺-doped fiber laser parameters pave the way toward a broad range of practical applications from telecommunications and sensing to scientific research. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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7 pages, 1989 KiB

Open AccessCommunication

Development of a Mode-Locked Fiber Laser Utilizing a Niobium Diselenide Saturable Absorber

by Weiqin Guo, Ling Zhang, Xiaosheng Xiao, Xingxing Li, Zhigang Yin, Hui Ning, Xin Zhang and Xingwang Zhang

Photonics 2023, 10(6), 610; https://doi.org/10.3390/photonics10060610 - 25 May 2023

Cited by 3 | Viewed by 978

Abstract

The saturable absorber of niobium diselenide (NbSe₂), with a wide working bandwidth and excellent nonlinear optical response, was prepared using liquid-phase exfoliation. Its saturation intensity and modulation depth were 5.35 MW/cm² and 6.3%, respectively. Stable mode-locking with a center wavelength [...] Read more.

The saturable absorber of niobium diselenide (NbSe₂), with a wide working bandwidth and excellent nonlinear optical response, was prepared using liquid-phase exfoliation. Its saturation intensity and modulation depth were 5.35 MW/cm² and 6.3%, respectively. Stable mode-locking with a center wavelength of 1558.7 nm of an erbium-doped fiber laser based on a NbSe₂ saturable absorber was successfully achieved. The maximum average output power of the mode-locked laser was 6.93 mW, with a pulse width of 1.3 ps and a repetition rate of 25.31 MHz at a pump power of 550 mW. The results show that NbSe₂ is a promising photoelectric modulation material owing to its excellent nonlinear optical properties. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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22 pages, 13671 KiB

Open AccessArticle

Frequency Comb Generation Based on Brillouin Random Lasing Oscillation and Four-Wave Mixing Assisted with Nonlinear Optical Loop Mirror

by Yuxi Pang, Shaonian Ma, Qiang Ji, Xian Zhao, Yongfu Li, Zengguang Qin, Zhaojun Liu and Yanping Xu

Photonics 2023, 10(3), 296; https://doi.org/10.3390/photonics10030296 - 11 Mar 2023

Cited by 5 | Viewed by 1567

Abstract

A frequency comb generator (FCG) based on dual-cavity Brillouin random fiber lasing oscillation in the 1.5 μm telecon spectral window is established and experimentally demonstrated. In the half-open main cavity of the dual cavity, the stimulated Brillouin scattering in highly nonlinear fiber (HNLF) [...] Read more.

A frequency comb generator (FCG) based on dual-cavity Brillouin random fiber lasing oscillation in the 1.5 μm telecon spectral window is established and experimentally demonstrated. In the half-open main cavity of the dual cavity, the stimulated Brillouin scattering in highly nonlinear fiber (HNLF) and Rayleigh scattering in single-mode fiber are employed to provide sufficient Brillouin gain and the randomly distributed feedback, respectively, for random mode resonance. The sub-cavity includes an Er-doped fiber amplifier to couple back and boost lower-order Stokes and anti-Stokes light for the cascade of stimulated Brillouin scattering to generate multiple higher-order Stokes and anti-Stokes light. Meanwhile, efficient four-wave mixing is stimulated in the HNLF-based main cavity, further enhancing the number and intensity of the resonant Stokes and anti-Stokes light. By taking advantages of the unique transmission characteristics of nonlinear optical loop mirrors, the power deviation between Stokes and anti-Stokes lines is further optimized with 17 orders of stable Stokes lines and 15 orders of stable anti-Stokes lines achieved within the 10 dB power deviation, with maximum optical signal-to-noise ratio (OSNR) of ~22 dB and ~17 dB and minimum OSNR of ~10 dB and ~7.5 dB for Stokes and anti-Stokes lines, respectively. In addition, the dynamic characteristics of the proposed FCG have been experimentally investigated. Such an FCG with fixed frequency spacing will find promising applications in fields of optical communication, microwave, optical sensing, etc. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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12 pages, 28842 KiB

Open AccessArticle

Study on the Technology and Mechanism of Cleaning Architectural Aluminum Formwork for Concrete Pouring by High Energy and High Repetition Frequency Pulsed Laser

by Kun Gao, Jinjun Xu, Yue Zhu, Zhiyan Zhang and Quansheng Zeng

Photonics 2023, 10(3), 242; https://doi.org/10.3390/photonics10030242 - 22 Feb 2023

Cited by 3 | Viewed by 1313

Abstract

In the field of construction, the surface of architectural aluminum formwork for concrete pouring will remain the concrete adhesion layer of heterogeneous composite structures. In view of the difficulty of removing the concrete adhesion layer, we studied the technology and mechanism of removing [...] Read more.

In the field of construction, the surface of architectural aluminum formwork for concrete pouring will remain the concrete adhesion layer of heterogeneous composite structures. In view of the difficulty of removing the concrete adhesion layer, we studied the technology and mechanism of removing the concrete adhesion layer by laser cleaning technology in this paper. We analyzed the composition and distribution characteristics of residual concrete on the surface of architectural aluminum formwork, set up a laser cleaning test system, carried out laser cleaning experiments on the concrete layer on the surface of architectural aluminum formwork under different storage times, and analyzed the mechanism of removing the concrete adhesion layer by laser cleaning. The experimental results showed that the residual time of concrete will affect the quality and efficiency of laser cleaning concrete residue on the surface of architectural aluminum formwork for concrete pouring. For concrete residues with short residual time, lasering can achieve efficient and high-quality cleaning. A nanosecond pulsed laser could strengthen the surface hardness of the aluminum alloy template during cleaning, which is helpful in improving the durability of the aluminum alloy template. The main mechanisms of laser cleaning to remove the concrete adhesion layer on the surface of architectural aluminum formwork is that the bubbles and water bubbles in the loose structure of concrete instantly absorb high-energy laser and make the concrete aggregate continuously air-burst. This paper provides technological and theoretical support for the application of laser cleaning technology to remove residual concrete on the surface of architectural aluminum formwork for concrete pouring in the field of construction. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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6 pages, 970 KiB

Open AccessCommunication

1.1–1.6 μm Multi-Wavelength Random Raman Fiber Laser

by Chunhua Hu and Ping Sun

Photonics 2023, 10(2), 164; https://doi.org/10.3390/photonics10020164 - 03 Feb 2023

Cited by 4 | Viewed by 1318

Abstract

Multi-wavelength fiber lasers have attracted great attention due to their application value in many fields. In this work, we demonstrated a seven-wavelength random Raman fiber laser in the range of 1.1–1.6 μm. A piece of 1-km-long high Raman gain optical fiber is utilized [...] Read more.

Multi-wavelength fiber lasers have attracted great attention due to their application value in many fields. In this work, we demonstrated a seven-wavelength random Raman fiber laser in the range of 1.1–1.6 μm. A piece of 1-km-long high Raman gain optical fiber is utilized as the gain medium. The 1st-order to 7th-order Stokes waves are located, respectively, at 1133 nm, 1194 nm, 1260 nm, 1332 nm, 1414 nm, 1504 nm, and 1606 nm. In the 3-dB bandwidth of optical spectra of 1st-order and 2nd-order Stokes waves, four peaks with an average spacing of 1 nm and 20 peaks with an average spacing of 0.45 nm respectively, are recorded. Pumped by a 1080 nm/12.5 W/220 ns laser, the maximum output power can reach 4.16 W, corresponding to the optical-to-optical conversion efficiency of ~30.7%. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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10 pages, 1775 KiB

Open AccessArticle

Orthogonally Polarized Dual-Wavelength Gain-Switched Ho:LuLiF₄ Pulse Laser

by Guanqu Hu, Jinhui Cui, Fengjun Tian, Zhengxin Gao, Shixiong Yan, Sichen Liu, Xinlu Zhang and Li Li

Photonics 2023, 10(1), 62; https://doi.org/10.3390/photonics10010062 - 06 Jan 2023

Cited by 1 | Viewed by 1592

Abstract

A compact, orthogonally polarized, gain-switched a-cut Ho:LuLiF₄ laser with intra-cavity pumping by a self-Q-switched Tm:YAP laser is demonstrated here for the first time. The π-polarization laser at 2052 nm and σ-polarization laser at 2066 nm were experimentally observed with the maximum output [...] Read more.

A compact, orthogonally polarized, gain-switched a-cut Ho:LuLiF₄ laser with intra-cavity pumping by a self-Q-switched Tm:YAP laser is demonstrated here for the first time. The π-polarization laser at 2052 nm and σ-polarization laser at 2066 nm were experimentally observed with the maximum output power values of 299 mW and 126 mW, respectively, and the two polarization directions were always kept mutually orthogonal as the pump power increased. The ratio of the output power between the two orthogonal polarization lasers was nearly 1:1 at a pump power of 18.4 W. The minimum pulse width of the Ho:LLF laser was 326 ns, the maximum repetition rate was 24 kHz, and the maximum average energy was 28 μJ. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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14 pages, 2518 KiB

Open AccessArticle

Chiral Dual-Core Photonic Crystal Fiber for an Efficient Circular Polarization Beam Splitter

by She Li, Yibing Li, Hongwei Lv, Changtong Ji, Hongze Gao and Qian Sun

Photonics 2023, 10(1), 45; https://doi.org/10.3390/photonics10010045 - 01 Jan 2023

Cited by 6 | Viewed by 1570

Abstract

As a function of a circular polarization beam splitter (CPBS), combining a linear polarization beam splitter with a quarter-wave plate results in a polarization error in a circular polarization fiber-optic circuit. To relieve the error, chiral dual-core photonic crystal fiber (DC-PCF) is investigated [...] Read more.

As a function of a circular polarization beam splitter (CPBS), combining a linear polarization beam splitter with a quarter-wave plate results in a polarization error in a circular polarization fiber-optic circuit. To relieve the error, chiral dual-core photonic crystal fiber (DC-PCF) is investigated as a kind of an efficient circular polarization beam splitter by using the chiral plane-wave expansion (PWE) method. On the basis of the competitive effect in polarization and coupling length between the circular asymmetry of the structure and the chirality of the medium, the effects of the structure and the chirality are analyzed. The numerical results demonstrate that a CPBS needs the weak circular asymmetry in its structure and a relatively stronger chirality of the medium. Then, a kind of CPBS based on chiral DC-PCF is designed with weaker chirality, with a central wavelength of 1.55 μm. The simulation shows the superior performance of having a shorter coupling length and a higher extinction ratio. Furthermore, the dual-wavelength of 1.55 μm and 1.30 μm with left-circular polarization can further be separated by the corresponding chiral DC-PCF. The results show promising applications for the circular polarized multiplexer/demultiplexer in fiber laser communication systems. Full article

(This article belongs to the Special Issue Fiber Laser and Their Applications)

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