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3 pages, 169 KiB

Open AccessEditorial

Editorial for the Special Issue on “Advances in Middle Infrared Laser Crystals and Its Applications”

by Xiaoming Duan, Renqin Dou, Linjun Li and Xiaotao Yang

Crystals 2022, 12(5), 643; https://doi.org/10.3390/cryst12050643 - 30 Apr 2022

Viewed by 1498

Abstract

In the past two decades, there has been a growing interest in middle infrared (mid-IR) laser crystals and its application to achieve mid-IR laser radiations, which has been benefited by the development of novel mid-infrared crystals and the improving quality of traditional mid-IR [...] Read more.

In the past two decades, there has been a growing interest in middle infrared (mid-IR) laser crystals and its application to achieve mid-IR laser radiations, which has been benefited by the development of novel mid-infrared crystals and the improving quality of traditional mid-IR crystals [...] Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

Research

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9 pages, 1818 KiB

Open AccessArticle

High-Beam-Quality and High-Brightness 532 nm Laser with Output Power 96 W

by Hongcai Liu, Qingxuan Li, Yu Ding, Xuesheng Liu, Jiapeng Hu, Boyi Yang, Youqiang Liu and Zhiyong Wang

Crystals 2023, 13(2), 290; https://doi.org/10.3390/cryst13020290 - 8 Feb 2023

Cited by 14 | Viewed by 2528

Abstract

We developed a high-power, double-intracavity-frequency, diode-side-pumped, Q-switched Nd:YAG laser. The thermal birefringence effect of Nd:YAG crystal was compensated by a quartz rotating mirror, and the stable cavity structure was designed according to the thermal focal length of a single module. A 532 nm [...] Read more.

We developed a high-power, double-intracavity-frequency, diode-side-pumped, Q-switched Nd:YAG laser. The thermal birefringence effect of Nd:YAG crystal was compensated by a quartz rotating mirror, and the stable cavity structure was designed according to the thermal focal length of a single module. A 532 nm laser with a maximum linearly polarized output power of 96 W was obtained at a pumping power of 1300 W and repetition rate of 10 kHz. The pulse width was 55.8 ns, and the beam quality was measured to be M²_x = 5.98, M²_y = 8.14 at the maximum output power; therefore, a brightness as high as 6.97 × 10⁸ W·cm⁻²·Sr was achieved. To the best of our knowledge, this is the highest brightness obtained for a high-power Nd:YAG laser at 532 nm. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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6 pages, 1793 KiB

Open AccessFeature PaperArticle

Intra-Cavity Tm:YAG-Ho:GdVO₄ Laser with near Diffraction Limited Beam Quality

by Tongyu Liu, Yu Ding, Mengmeng Yan and Qinggang Ji

Crystals 2022, 12(8), 1113; https://doi.org/10.3390/cryst12081113 - 9 Aug 2022

Viewed by 1490

Abstract

In this study, an Er:YAG laser pumped intra-cavity Tm:YAG-Ho:GdVO₄ laser was built and debuted at room temperature. At an incident pump power of 9.2 W, this laser obtained a maximum output power of 1.6 W with a slope efficiency of 28.0%. Additionally, [...] Read more.

In this study, an Er:YAG laser pumped intra-cavity Tm:YAG-Ho:GdVO₄ laser was built and debuted at room temperature. At an incident pump power of 9.2 W, this laser obtained a maximum output power of 1.6 W with a slope efficiency of 28.0%. Additionally, the M² factors at the maximum output power were measured to be 1.06 and 1.03 in the x and y directions, respectively. The results showed that the intra-cavity pumping method of combining thulium and holmium crystals as the gain medium was an effective way to obtain a 2 μm laser with near diffraction limited beam quality. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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5 pages, 1617 KiB

Open AccessArticle

Efficient Ho:YVO₄ Laser Double-Pass-Pumped by a Wavelength-Stabilized Laser Diode

by Yuhai Li, Cheng Zhang and Qinggang Ji

Crystals 2022, 12(3), 320; https://doi.org/10.3390/cryst12030320 - 25 Feb 2022

Cited by 8 | Viewed by 2318

Abstract

A Ho:YVO₄ laser double-pass-pumped with a 1.91 μm wavelength-stabilized laser diode is presented in this paper. The maximum output power was up to 8.7 W, with a wavelength of 2052.4 nm and a slope efficiency of 37.4%. The M² factors in [...] Read more.

A Ho:YVO₄ laser double-pass-pumped with a 1.91 μm wavelength-stabilized laser diode is presented in this paper. The maximum output power was up to 8.7 W, with a wavelength of 2052.4 nm and a slope efficiency of 37.4%. The M² factors in the x and y directions were 1.8 and 1.6 at the maximum output power, respectively. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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12 pages, 3894 KiB

Open AccessArticle

The Influence of Angstrom-Scale Roughness on the Laser-Induced Damage Threshold of Single-Crystal ZnGeP₂

by Nikolai Yudin, Andrei Khudoley, Mikhail Zinoviev, Sergey Podzvalov, Elena Slyunko, Elena Zhuravleva, Maxim Kulesh, Gennadij Gorodkin, Pavel Kumeysha and Oleg Antipov

Crystals 2022, 12(1), 83; https://doi.org/10.3390/cryst12010083 - 8 Jan 2022

Cited by 7 | Viewed by 1894

Abstract

Magnetorheological processing was applied to polish the working surfaces of single-crystal ZnGeP₂, in which a non-aqueous liquid with the magnetic particles of carbonyl iron with the addition of nanodiamonds was used. Samples of a single-crystal ZnGeP₂ with an Angstrom level [...] Read more.

Magnetorheological processing was applied to polish the working surfaces of single-crystal ZnGeP₂, in which a non-aqueous liquid with the magnetic particles of carbonyl iron with the addition of nanodiamonds was used. Samples of a single-crystal ZnGeP₂ with an Angstrom level of surface roughness were received. The use of magnetorheological polish allowed the more accurate characterization of the possible structural defects that emerged on the surface of a single crystal and had a size of ~0.5–1.5 μm. The laser-induced damage threshold (LIDT) value at the indicated orders of magnitude of the surface roughness parameters was determined not by the quality of polishing, but by the number of point depressions caused by the physical limitations of the structural configuration of the crystal volume. These results are in good agreement with the assumption made about a significant effect of the concentration of dislocations in a ZnGeP₂ crystal on LIDT. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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12 pages, 3529 KiB

Open AccessArticle

Influence of the Characteristics of Multilayer Interference Antireflection Coatings Based on Nb, Si, and Al Oxides on the Laser-Induced Damage Threshold of ZnGeP₂ Single Crystal

by Nikolai Nikolayevich Yudin, Mikhail Zinoviev, Vladislav Gladkiy, Evgeny Moskvichev, Igor Kinyaevsky, Sergey Podzyvalov, Elena Slyunko, Elena Zhuravleva, Anastasia Pfaf, Nikolai Aleksandrovich Yudin and Maxim Kulesh

Crystals 2021, 11(12), 1549; https://doi.org/10.3390/cryst11121549 - 10 Dec 2021

Cited by 10 | Viewed by 2297

Abstract

In this work, the effect of the defect structure and the parameters of antireflection interference coatings based on alternating layers of Nb₂O₅/Al₂O₃ and Nb₂O₅/SiO₂ layers on the laser-induced damage threshold of [...] Read more.

In this work, the effect of the defect structure and the parameters of antireflection interference coatings based on alternating layers of Nb₂O₅/Al₂O₃ and Nb₂O₅/SiO₂ layers on the laser-induced damage threshold of ZGP crystals under the action of Ho:YAG laser radiation at a wavelength of 2.097 μm was determined. Coating deposition was carried out using the ion-beam sputtering method. The laser-induced damage threshold of the sample with a coating based on alternating layers Nb₂O₅ and SiO₂ was W_0d = 1.8 J/cm². The laser-induced damage threshold of the coated sample based on alternating layers of Nb₂O₅ and Al₂O₃ was W_0d = 2.35 J/cm². It has been found that the presence of silicon conglomerates in an interference antireflection coating leads to a decrease in the laser-induced damage threshold of a nonlinear crystal due to local mechanical stresses and the scattering of incident laser radiation. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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8 pages, 2355 KiB

Open AccessArticle

β-Ga₂O₃ Used as a Saturable Sbsorber to Realize Passively Q-Switched Laser Output

by Baizhong Li, Qiudi Chen, Peixiong Zhang, Ruifeng Tian, Lu Zhang, Qinglin Sai, Bin Wang, Mingyan Pan, Youchen Liu, Changtai Xia, Zhenqiang Chen and Hongji Qi

Crystals 2021, 11(12), 1501; https://doi.org/10.3390/cryst11121501 - 3 Dec 2021

Cited by 3 | Viewed by 1956

Abstract

β-Ga₂O₃ crystals have attracted great attention in the fields of photonics and photoelectronics because of their ultrawide band gap and high thermal conductivity. Here, a pure β-Ga₂O₃ crystal was successfully grown by the optical floating zone (OFZ) [...] Read more.

β-Ga₂O₃ crystals have attracted great attention in the fields of photonics and photoelectronics because of their ultrawide band gap and high thermal conductivity. Here, a pure β-Ga₂O₃ crystal was successfully grown by the optical floating zone (OFZ) method, and was used as a saturable absorber to realize a passively Q-switched all-solid-state 1 μm laser for the first time. By placing the as-grown β-Ga₂O₃ crystal into the resonator of the Nd:GYAP solid-state laser, Q-switched pulses at the center wavelength of 1080.4 nm are generated under a output coupling of 10%. The maximum output power is 191.5 mW, while the shortest pulse width is 606.54 ns, and the maximum repetition frequency is 344.06 kHz. The maximum pulse energy and peak power are 0.567 μJ and 0.93 W, respectively. Our experimental results show that the β-Ga₂O₃ crystal has great potential in the development of an all-solid-state 1 μm pulsed laser. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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13 pages, 3698 KiB

Open AccessArticle

Energy Transfer and Cross-Relaxation Induced Efficient 2.78 μm Emission in Er³⁺/Tm³⁺: PbF₂ mid-Infrared Laser Crystal

by Jiayu Liao, Qiudi Chen, Xiaochen Niu, Peixiong Zhang, Huiyu Tan, Fengkai Ma, Zhen Li, Siqi Zhu, Yin Hang, Qiguo Yang and Zhenqiang Chen

Crystals 2021, 11(9), 1024; https://doi.org/10.3390/cryst11091024 - 26 Aug 2021

Cited by 5 | Viewed by 2068

Abstract

An efficient enhancement of 2.78 μm emission from the transition of Er³⁺: ⁴I_11/2 → ⁴I_13/2 by Tm³⁺ introduction in the Er/Tm: PbF₂ crystal was grown by the Bridgman technique for the first time. The spectroscopic [...] Read more.

An efficient enhancement of 2.78 μm emission from the transition of Er³⁺: ⁴I_11/2 → ⁴I_13/2 by Tm³⁺ introduction in the Er/Tm: PbF₂ crystal was grown by the Bridgman technique for the first time. The spectroscopic properties, energy transfer mechanism, and first-principles calculations of as-grown crystals were investigated in detail. The co-doped Tm³⁺ ion can offer an appropriate sensitization and deactivation effect for Er³⁺ ion at the same time in PbF₂ crystal under the pump of conventional 800 nm laser diodes (LDs). With the introduction of Tm³⁺ ion into the Er³⁺: PbF₂ crystal, the Er/Tm: PbF₂ crystal exhibited an enhancing 2.78 μm mid-infrared (MIR) emission. Furthermore, the cyclic energy transfer mechanism that contains several energy transfer processes and cross-relaxation processes was proposed, which would well achieve the population inversion between the Er³⁺: ⁴I_11/2 and Er³⁺: ⁴I_13/2 levels. First-principles calculations were performed to find that good performance originates from the uniform distribution of Er³⁺ and Tm³⁺ ions in PbF₂ crystal. This work will provide an avenue to design MIR laser materials with good performance. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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12 pages, 4209 KiB

Open AccessArticle

A Study of the Characteristics of Plasma Generated by Infrared Pulse Laser-Induced Fused Silica

by Lixue Wang, Xudong Sun, Congrui Geng, Zequn Zhang and Jixing Cai

Crystals 2021, 11(8), 1009; https://doi.org/10.3390/cryst11081009 - 23 Aug 2021

Cited by 2 | Viewed by 2107

Abstract

When high energy infrared laser pulses are incident on fused silica, the surface of the fused silica is damaged and a laser-induced plasma is produced. Based on the theory of fluid mechanics and gas dynamics, a two-dimensional axisymmetric gas dynamic model was established [...] Read more.

When high energy infrared laser pulses are incident on fused silica, the surface of the fused silica is damaged and a laser-induced plasma is produced. Based on the theory of fluid mechanics and gas dynamics, a two-dimensional axisymmetric gas dynamic model was established to simulate the plasma generation process of fused silica induced by a millisecond pulse laser. The results show that the temperature of the central region irradiated by the laser is the highest, and the plasma is first produced in this region. When the laser energy density is 1.0 × 10⁴ J/cm² and the pulse width is 0.2 ms, the maximum expansion velocity of the laser-induced plasma is 17.7 m/s. Under the same experimental conditions, the results of the simulation and experiment are in good agreement. With an increase in pulse width, the plasma expansion rate gradually decreases. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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22 pages, 7297 KiB

Open AccessEditor’s ChoiceArticle

Investigation of Mid-Infrared Broadband Second-Harmonic Generation in Non-Oxide Nonlinear Optic Crystals

by Ilhwan Kim, Donghwa Lee and Kwang Jo Lee

Crystals 2021, 11(8), 921; https://doi.org/10.3390/cryst11080921 - 8 Aug 2021

Cited by 6 | Viewed by 3515

Abstract

The mid-infrared (mid-IR) continuum generation based on broadband second harmonic generation (SHG) (or difference frequency generation) is of great interest in a wide range of applications such as free space communications, environmental monitoring, thermal imaging, high-sensitivity metrology, gas sensing, and molecular fingerprint spectroscopy. [...] Read more.

The mid-infrared (mid-IR) continuum generation based on broadband second harmonic generation (SHG) (or difference frequency generation) is of great interest in a wide range of applications such as free space communications, environmental monitoring, thermal imaging, high-sensitivity metrology, gas sensing, and molecular fingerprint spectroscopy. The second-order nonlinear optic (NLO) crystals have been spotlighted as a material platform for converting the wavelengths of existing lasers into the mid-IR spectral region or for realizing tunable lasers. In particular, the spectral coverage could be extended to ~19 µm with non-oxide NLO crystals. In this paper, we theoretically and numerically investigated the broadband SHG properties of non-oxide mid-IR crystals in three categories: chalcopyrite semiconductors, defect chalcopyrite, and orthorhombic ternary chalcogenides. The technique is based on group velocity matching between interacting waves in addition to birefringent phase matching. We will describe broadband SHG characteristics in terms of beam propagation directions, spectral positions of resonance, effective nonlinearities, spatial walk-offs between interacting beams, and spectral bandwidths. The results will show that the spectral bandwidths of the fundamental wave allowed for broadband SHG to reach several hundreds of nm. The corresponding SH spectral range spans from 1758.58 to 4737.18 nm in the non-oxide crystals considered in this study. Such broadband SHG using short pulse trains can potentially be applied to frequency up-conversion imaging in the mid-IR region, in information transmission, and in nonlinear optical signal processing. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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9 pages, 3845 KiB

Open AccessArticle

Mid-IR Optical Property of Dy:CaF₂-SrF₂ Crystal Fabricated by Multicrucible Temperature Gradient Technology

by Lihe Zheng, Jianbin Zhao, Yangxiao Wang, Weichao Chen, Fangfang Ruan, Hui Lin, Yanyan Xue, Jian Liu, Yang Liu, Ruiqin Yang, Haifeng Lu, Xiaodong Xu and Liangbi Su

Crystals 2021, 11(8), 907; https://doi.org/10.3390/cryst11080907 - 31 Jul 2021

Cited by 8 | Viewed by 2562

Abstract

Dy³⁺-doped CaF₂-SrF₂ crystals with various Dy³⁺ dopant concentrations were synthesized by multicrucible temperature gradient technology (MC-TGT). Dy:CaF₂-SrF₂ crystals were fluorite structured and crystallized in cubic

F m \bar{3} m

space group, as characterized [...] Read more.

Dy³⁺-doped CaF₂-SrF₂ crystals with various Dy³⁺ dopant concentrations were synthesized by multicrucible temperature gradient technology (MC-TGT). Dy:CaF₂-SrF₂ crystals were fluorite structured and crystallized in cubic

F m \bar{3} m

space group, as characterized by X-ray diffraction. The crystallographic site concentration was calculated from the measured density by Archimedes’ hydrostatic weighing principle. The optical transmission reached over 90% with a sample thickness of 1.0 mm. The Sellmeier dispersion formula was obtained following the measured refractive index in a mid-IR range of 1.7–11 μm. Absorption coefficients of 6.06 cm⁻¹ and 12.71 cm⁻¹ were obtained at 804 nm and 1094 nm in 15% Dy:CaF₂-SrF₂ crystal. The fluorescence spectra of 15 at.% Dy:CaF₂-SrF₂ showed the strongest wavelength peak at 2919 nm with a full width at half maximum (FWHM) of 267 nm under an excitation wavelength of 808 nm. The fluorescence lifetimes were illustrated for different Dy³⁺ dopant levels of 5%, 10% and 15%. The results indicate that the Dy:CaF₂-SrF₂ crystal is a promising candidate for compact mid-IR lasers. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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5 pages, 1089 KiB

Open AccessArticle

Study on the Internal Mechanism of APD Photocurrent Characteristics Caused by the ms Pulsed Infrared Laser Irradiation

by Liang Chen, Di Wang, Guang-Yong Jin and Zhi Wei

Crystals 2021, 11(8), 884; https://doi.org/10.3390/cryst11080884 - 29 Jul 2021

Cited by 1 | Viewed by 1875

Abstract

In this paper, the sampling current characteristics of the external circuit and the internal mechanism of the current generation in APD irradiated by a millisecond pulse laser were studied. The photocurrent of APD irradiated by a millisecond pulse laser with different energy densities [...] Read more.

In this paper, the sampling current characteristics of the external circuit and the internal mechanism of the current generation in APD irradiated by a millisecond pulse laser were studied. The photocurrent of APD irradiated by a millisecond pulse laser with different energy densities was obtained by the sampling resistance of the external circuit. The photocurrent can be divided into a photocurrent stage, conduction stage and recovery stage in the time domain. This is mainly due to the carrier flow in APD, which leads to the lowering of the barrier between the PN junction. The research results of this paper can be extended to the response of the detector to the high-power infrared pulse laser and provide a certain experimental basis for the design of a millisecond pulse infrared laser detection circuit. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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6 pages, 1629 KiB

Open AccessArticle

Temperature Rise Characteristics of Silicon Avalanche Photodiodes in Different External Capacitance Circuits Irradiated by Infrared Millisecond Pulse Laser

by Liang Chen, Zhi Wei, Di Wang, Hong-Xu Liu and Guang-Yong Jin

Crystals 2021, 11(8), 866; https://doi.org/10.3390/cryst11080866 - 26 Jul 2021

Cited by 1 | Viewed by 1841

Abstract

We experimentally studied the interaction between a millisecond pulse laser and silicon avalanche photodiode (Si-APD) in an external capacitance circuit. The temperature rise law of Si-APD irradiated by a millisecond pulse laser under different external capacitance conditions was obtained. The results show that [...] Read more.

We experimentally studied the interaction between a millisecond pulse laser and silicon avalanche photodiode (Si-APD) in an external capacitance circuit. The temperature rise law of Si-APD irradiated by a millisecond pulse laser under different external capacitance conditions was obtained. The results show that the surface temperature rise in a Si-APD is strongly dependent on the external capacitance. That is, the smaller the external capacitance, the smaller the surface temperature rise. The effect of the external capacitance on the surface temperature rise in a Si-APD was investigated for the first time in the field of laser damage. The research results have a certain practical significance for the damage and protection of mid-infrared detectors. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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10 pages, 2675 KiB

Open AccessArticle

Formation Laws of Direction of Fano Line-Shape in a Ring MIM Plasmonic Waveguide Side-Coupled with a Rectangular Resonator and Nano-Sensing Analysis of Multiple Fano Resonances

by Dayong Zhang, Li Cheng and Zuochun Shen

Crystals 2021, 11(7), 819; https://doi.org/10.3390/cryst11070819 - 14 Jul 2021

Cited by 8 | Viewed by 2437

Abstract

Plasmonic MIM (metal-insulator-metal) waveguides based on Fano resonance have been widely researched. However, the regulation of the direction of the line shape of Fano resonance is rarely mentioned. In order to study the regulation of the direction of the Fano line-shape, a Fano [...] Read more.

Plasmonic MIM (metal-insulator-metal) waveguides based on Fano resonance have been widely researched. However, the regulation of the direction of the line shape of Fano resonance is rarely mentioned. In order to study the regulation of the direction of the Fano line-shape, a Fano resonant plasmonic system, which consists of a MIM waveguide coupled with a ring resonator and a rectangle resonator, is proposed and investigated numerically via FEM (finite element method). We find the influencing factors and formation laws of the ‘direction’ of the Fano line-shape, and the optimal condition for the generation of multiple Fano resonances; and the application in refractive index sensing is also well studied. The conclusions can provide a clear theoretical reference for the regulation of the direction of the line shape of Fano resonance and the generation of multi Fano resonances in the designs of plasmonic nanodevices. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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7 pages, 1607 KiB

Open AccessArticle

Experimental Investigation of Double-End Pumped Tm, Ho: GdVO₄ Laser at Cryogenic Temperature

by Yanqiu Du, Tongyu Dai, Hui Sun, Hui Kang, Hongyang Xia, Jiaqi Tian, Xia Chen and Baoquan Yao

Crystals 2021, 11(7), 798; https://doi.org/10.3390/cryst11070798 - 8 Jul 2021

Cited by 8 | Viewed by 2051

Abstract

We describe comparatively cryogenically cooled Tm, Ho: GdVO₄ lasers with an emission wavelength of 2.05 μm under continuous wave and pulse operating mode. By varying the transmittance of output couplers to be 0.40 for a continuous wave laser, the maximum output power [...] Read more.

We describe comparatively cryogenically cooled Tm, Ho: GdVO₄ lasers with an emission wavelength of 2.05 μm under continuous wave and pulse operating mode. By varying the transmittance of output couplers to be 0.40 for a continuous wave laser, the maximum output power of 7.4 W was generated with a slope efficiency of 43.3% when the absorbed pump power was increased to 18.7 W. For passively Q-switched lasers, the output characteristics were researched through altering pump mode radius. When the pump mode radius focused into the Tm, Ho: GdVO₄ center equaled near 600 μm, the peak power was increased to be the maximum value of 9.9 kW at the absorbed pump power of 11.8 W. The pulse energy of 0.39 mJ was achieved at the same absorbed pump power with repetition of 5.7 kHz. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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6 pages, 1929 KiB

Open AccessArticle

The Investigation on Mid-Far Infrared Nonlinear Crystal AgGaGe₅Se₁₂ (AGGSe)

by Youbao Ni, Qianqian Hu, Haixin Wu, Weimin Han, Xuezhou Yu and Mingsheng Mao

Crystals 2021, 11(6), 661; https://doi.org/10.3390/cryst11060661 - 10 Jun 2021

Cited by 2 | Viewed by 2672

Abstract

3–5, 8–14 μm mid-far infrared (MF-IR) coherent lights generated by nonlinear optical (NLO) crystals are crucial for many industrial and military applications. AgGaGe₅Se₁₂ (AGGSe) is a promising NLO candidate because of its good optical performance. In this paper, the large [...] Read more.

3–5, 8–14 μm mid-far infrared (MF-IR) coherent lights generated by nonlinear optical (NLO) crystals are crucial for many industrial and military applications. AgGaGe₅Se₁₂ (AGGSe) is a promising NLO candidate because of its good optical performance. In this paper, the large AGGSe single crystal of 35 mm diameter and 80 mm length was obtained by the seed-aided Bridgman method. The crystalline quality was characterized with X-ray diffraction, rocking curve, transmission spectrum. The FWHM of the (210) peak was about 0.05° and the IR transmission was about 60% (1–10 μm, 6 mm thick). Additionally, it performed well in 8 μm frequency doubling, with a maximum output power of about 41 mW, corresponding to an optical-to-optical conversion efficiency of 3.2%. The laser induced damage threshold (LIDT) value was about 200 MW/cm² (1.06 μm, 20 ns, 1 Hz). Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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7 pages, 13900 KiB

Open AccessArticle

A High-Energy, Narrow-Pulse-Width, Long-Wave Infrared Laser Based on ZGP Crystal

by Chuanpeng Qian, Ting Yu, Jing Liu, Yuyao Jiang, Sijie Wang, Xiangchun Shi, Xisheng Ye and Weibiao Chen

Crystals 2021, 11(6), 656; https://doi.org/10.3390/cryst11060656 - 9 Jun 2021

Cited by 11 | Viewed by 3093

Abstract

In this paper, we present a high-energy, narrow pulse-width, long-wave infrared laser based on a ZnGeP₂ (ZGP) optical parametric oscillator (OPO). The pump source is a 2.1 μm three -stage Ho:YAG master oscillator power-amplifier (MOPA). At a repetition frequency of 1 kHz, [...] Read more.

In this paper, we present a high-energy, narrow pulse-width, long-wave infrared laser based on a ZnGeP₂ (ZGP) optical parametric oscillator (OPO). The pump source is a 2.1 μm three -stage Ho:YAG master oscillator power-amplifier (MOPA). At a repetition frequency of 1 kHz, the Ho:YAG MOPA system outputs the maximal average power of 52.1 W, which corresponds to the shortest pulse width of 14.40 ns. By using the Ho:YAG MOPA system as the pump source, the maximal average output powers of 3.15 W at 8.2 μm and 11.4 W at 2.8 μm were achieved in a ZGP OPO. The peak wavelength and linewidth (FWHM) of the long-wave infrared laser were 8156 nm and 270 nm, respectively. At the maximal output level, the pulse width and beam quality factor M² were measured to be 8.10 ns and 6.2, respectively. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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9 pages, 1326 KiB

Open AccessArticle

High-Efficiency Ho:YAP Pulse Laser Pumped at 1989 nm

by Chao Niu, Yan Jiang, Ya Wen, Lu Zhao, Xinyu Chen, Chunting Wu and Tongyu Dai

Crystals 2021, 11(6), 595; https://doi.org/10.3390/cryst11060595 - 24 May 2021

Cited by 6 | Viewed by 2104

Abstract

A Tm:YAP laser with an output wavelength of 1989 nm was selected for the first time as the pump source of a Q-switched Ho:YAP laser. When the absorbed power was 30 W, an average power of 18.02 W with the pulse width of [...] Read more.

A Tm:YAP laser with an output wavelength of 1989 nm was selected for the first time as the pump source of a Q-switched Ho:YAP laser. When the absorbed power was 30 W, an average power of 18.02 W with the pulse width of 104.2 ns acousto-optic (AO) Q-switched Ho:YAP laser was obtained at a repetition frequency of 10 kHz. The slope efficiency was 70.11%, and the optical-optical conversion efficiency was 43.03%. The output center wavelength was 2129.22 nm with the line width of 0.74 nm. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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8 pages, 1357 KiB

Open AccessArticle

Experimental Study of Plasma Plume Analysis of Long Pulse Laser Irradiates CFRP and GFRP Composite Materials

by Yao Ma, Chao Xin, Wei Zhang and Guangyong Jin

Crystals 2021, 11(5), 545; https://doi.org/10.3390/cryst11050545 - 13 May 2021

Cited by 13 | Viewed by 2619

Abstract

The application of laser fabrication of fiber-reinforced polymer (FRP) has an irreplaceable advantage. However, the effect of the plasma generated in laser fabrication on the damage process is rarely mentioned. In order to further study the law and mechanism of laser processing, the [...] Read more.

The application of laser fabrication of fiber-reinforced polymer (FRP) has an irreplaceable advantage. However, the effect of the plasma generated in laser fabrication on the damage process is rarely mentioned. In order to further study the law and mechanism of laser processing, the laser process was measured. CFRP and GFRP materials were damaged by a 1064 nm millisecond pulsed laser. Moreover, the propagation velocity and breakdown time of plasma plume were compared. The results show that GFRP is more vulnerable to breakdown than CFRP under the same conditions. In addition, the variation of plasma plume and material surface temperature with the number of pulses was also studied. The results show that the variation trend is correlated, that is, the singularities occur at the second pulse. Based on the analysis of experimental phenomena, this paper provides guidance for plasma phenomena in laser processing of composite materials. Full article

(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)

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Advances in Middle Infrared Laser Crystals and Its Applications

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