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20 pages, 8497 KiB

Open AccessArticle

Synthesis of Magnetron-Sputtered TiN Thin-Films on Fiber Structures for Pulsed-Laser Emission and Refractive-Index Sensing Applications at 1550 nm

by Omar Gaspar Ramírez, Manuel García Méndez, Ricardo Iván Álvarez Tamayo and Patricia Prieto Cortés

Coatings 2023, 13(1), 95; https://doi.org/10.3390/coatings13010095 - 4 Jan 2023

Cited by 3 | Viewed by 2416

Abstract

In this work, a set of titanium nitrides thin-films was synthesized with the technique of reactive RF and DC magnetron-sputtering. To demonstrate the versatility and effectiveness of the deposition technique, thin films were deposited onto different fiber structures varying the deposition parameters for [...] Read more.

In this work, a set of titanium nitrides thin-films was synthesized with the technique of reactive RF and DC magnetron-sputtering. To demonstrate the versatility and effectiveness of the deposition technique, thin films were deposited onto different fiber structures varying the deposition parameters for optical applications as saturable absorbers in passively q-switched fiber lasers and as lossy mode resonance fiber refractometers. After deposition, optical and electronical properties of samples were characterized by UV–Vis and XPS spectroscopies, respectively. Samples presented coexisting phases of Ti nitride and oxide, where the nitride phase was non-stoichiometric metallic-rich, with a band gap in the range of E_g = 3.4–3.7 eV. For all samples, glass substrates were used as templates, and on top of them, optical fibers were mounted to be covered with their respective titanium compounds. Full article

(This article belongs to the Special Issue Advances in Thin Film Fabrication by Magnetron Sputtering)

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9 pages, 2027 KiB

Open AccessArticle

Laser Additive Manufacturing of Bulk Silicon Nitride Ceramic: Modeling versus Integral Transform Technique with Experimental Correlation

by Cristian N. Mihailescu, Mihai Oane, Bogdan A. Sava, Andrei C. Popescu, Mihail Elisa, Muhammad Arif Mahmood, Natalia Mihailescu, Ana V. Filip, Sinziana Andreea Anghel, Ion N. Mihailescu and Carmen Ristoscu

Crystals 2022, 12(8), 1155; https://doi.org/10.3390/cryst12081155 - 16 Aug 2022

Cited by 1 | Viewed by 2258

Abstract

A semi-analytical-numerical solution is theorized to describe the laser additive manufacturing via laser-bulk ceramic interaction modeling. The Fourier heat equation was used to infer the thermal distribution within the ceramic sample. Appropriate boundary conditions, including convection and radiation, were applied to the bulk [...] Read more.

A semi-analytical-numerical solution is theorized to describe the laser additive manufacturing via laser-bulk ceramic interaction modeling. The Fourier heat equation was used to infer the thermal distribution within the ceramic sample. Appropriate boundary conditions, including convection and radiation, were applied to the bulk sample. It was irradiated with a Gaussian spatial continuous mode fiber laser (λ = 1.075 µm) while a Lambert-Beer law was assumed to describe the laser beam absorption. A close correlation between computational predictions versus experimental results was validated in the case of laser additive manufacturing of silicon nitride bulk ceramics. The thermal field value rises but stays confined within the irradiated zone due to heat propagation with an infinite speed, a characteristic of the Fourier heat equation. An inverse correlation was observed between the laser beam scanning speed and thermal distribution intensity. Whenever the laser scanning speed increases, photons interact with and transfer less energy to the sample, resulting in a lower thermal distribution intensity. This model could prove useful for the description and monitoring of low-intensity laser beam-ceramic processing. Full article

(This article belongs to the Special Issue Additive Manufacturing: Experiments, Simulations and Data-Driven Modelling)

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13 pages, 4348 KiB

Open AccessArticle

Facile Synthesis of Monodispersed Titanium Nitride Quantum Dots for Harmonic Mode-Locking Generation in an Ultrafast Fiber Laser

by Ya-Tao Yang, Han-Wei Wu, Yuan Zou, Xue-Yang Fang, Shuang Li, Yu-Feng Song, Zhen-Hong Wang and Bin Zhang

Nanomaterials 2022, 12(13), 2280; https://doi.org/10.3390/nano12132280 - 1 Jul 2022

Cited by 14 | Viewed by 2887

Abstract

As a member of the transition metal nitride material family, titanium nitride (TiN) quantum dots (QDs) have attracted great attention in optical and electronic fields because of their excellent optoelectronic properties and favorable stability. Herein, TiN QDs were synthesized and served as a [...] Read more.

As a member of the transition metal nitride material family, titanium nitride (TiN) quantum dots (QDs) have attracted great attention in optical and electronic fields because of their excellent optoelectronic properties and favorable stability. Herein, TiN QDs were synthesized and served as a saturable absorber (SA) for an ultrafast fiber laser. Due to the strong nonlinear optical absorption characteristics with a modulation depth of ~33%, the typical fundamental mode-locked pulses and harmonics mode-locked pulses can be easily obtained in an ultrafast erbium-doped fiber laser with a TiN-QD SA. In addition, at the maximum pump power, harmonic mode-locked pulses with a repetition rate of ~1 GHz (164th order) and a pulse duration of ~1.45 ps are achieved. As far as we know, the repetition rate is the highest in the ultrafast fiber laser using TiN QDs as an SA. Thus, these experimental results indicate that TiN QDs can be considered a promising material, showing more potential in the category of ultrafast laser and nonlinear optics. Full article

(This article belongs to the Special Issue Molecular Beam Epitaxy Growth of Quantum Wires and Quantum Dots)

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13 pages, 3673 KiB

Open AccessArticle

Ti₃C₂T_x MXene Quantum Dots with Surface-Terminated Groups (-F, -OH, =O, -Cl) for Ultrafast Photonics

by Jianfeng Liu, Shanshan Chen, Junshan He, Runming Huang, Lili Tao, Yu Zhao and Yibin Yang

Nanomaterials 2022, 12(12), 2043; https://doi.org/10.3390/nano12122043 - 14 Jun 2022

Cited by 8 | Viewed by 3281

Abstract

Transition metal carbides and nitrides (MXenes) have attracted significant attention in photoelectric applications due to their highly tunable electronic and optical properties influenced by a flexible compositional or surface functional group regulation. Ti₃C₂T_x MXenes (-F, -OH, =O terminated) [...] Read more.

Transition metal carbides and nitrides (MXenes) have attracted significant attention in photoelectric applications due to their highly tunable electronic and optical properties influenced by a flexible compositional or surface functional group regulation. Ti₃C₂T_x MXenes (-F, -OH, =O terminated) used in previous ultrafast photonic studies are usually synthesized via a generic hydrofluoric acid (HF) etching strategy, which may cause numerous defects and thus impedes the optoelectronic properties of Ti₃C₂T_x. In this contribution, inspired by a much higher conductivity and carrier mobility of Ti₃C₂T_x (-F, -OH, =O, -Cl terminated) prepared from a minimally intensive layer delamination method (MILD) etching strategy, we further optimized it with a liquid-phase exfoliation (LPE) method to synthesize pure Ti₃C₂T_x quantum dots (QDs) for ultrafast photonic. Compared to the other QDs saturable absorber (SA) devices performed at 1550 nm, our SA device exhibited a relatively low saturation intensity (1.983 GW/cm⁻²) and high modulation depth (11.6%), allowing for a more easily mode-locked pulse generation. A distinguished ultrashort pulse duration of 466 fs centered at the wavelength of 1566.57 nm with a fundamental frequency of 22.78 MHz was obtained in the communication band. Considering the SA based on such a Ti₃C₂T_x QDs tapered fiber is the first exploration of Er³⁺-doped fiber laser (EDFL), this work will open up a new avenue for applications in ultrafast photonics. Full article

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12 pages, 5584 KiB

Open AccessReview

GaN Laser Diode Technology for Visible-Light Communications

by Stephen P. Najda, Piotr Perlin, Tadek Suski, Lucja Marona, Mike Leszczyński, Przemek Wisniewski, Szymon Stanczyk, Dario Schiavon, Thomas Slight, Malcolm A. Watson, Steffan Gwyn, Anthony E. Kelly and Scott Watson

Electronics 2022, 11(9), 1430; https://doi.org/10.3390/electronics11091430 - 29 Apr 2022

Cited by 31 | Viewed by 5161

Abstract

Gallium nitride (GaN) laser diodes (LDs) are considered for visible light communications (VLC) in free space, underwater, and in plastic optical fibers (POFs). A review of recent results is presented, showing high-frequency operation of AlGaInN laser diodes with data transmission rates up to [...] Read more.

Gallium nitride (GaN) laser diodes (LDs) are considered for visible light communications (VLC) in free space, underwater, and in plastic optical fibers (POFs). A review of recent results is presented, showing high-frequency operation of AlGaInN laser diodes with data transmission rates up to 2.5 Gbit/s in free space and underwater and high bandwidths of up to 1.38 GHz through 10 m of plastic optical fiber. Distributed feedback (DFB) GaN LDs are fabricated to achieve single-frequency operation. We report on single-wavelength emissions of GaN DFB LDs with a side-mode suppression ratio (SMSR) in excess of 35 dB. Full article

(This article belongs to the Special Issue Advances in Radio, Visible Light Communications, and Fiber Optics)

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7 pages, 1914 KiB

Open AccessArticle

Properties of Scalable Chirped-Pulse Optical Comb in Erbium-Doped Ultrafast All-Fiber Ring Laser

by Ilya O. Orekhov, Dmitriy A. Dvoretskiy, Stanislav G. Sazonkin, Yan Z. Ososkov, Anton O. Chernutsky, Aleksander Y. Fedorenko, Lev K. Denisov and Valeriy E. Karasik

Fibers 2021, 9(6), 36; https://doi.org/10.3390/fib9060036 - 2 Jun 2021

Cited by 4 | Viewed by 3141

Abstract

We report on a scalable chirped-pulse Er-doped all-fiber laser, passively mode-locked by single-wall carbon nitride nanotubes. The average output power is ~15 mW, which corresponds to a peak power of ~77 W, and pulse energy of ~1.9 nJ and was achieved using a [...] Read more.

We report on a scalable chirped-pulse Er-doped all-fiber laser, passively mode-locked by single-wall carbon nitride nanotubes. The average output power is ~15 mW, which corresponds to a peak power of ~77 W, and pulse energy of ~1.9 nJ and was achieved using a single amplification stage. We observed chirped-pulse generation with a duration of ~24.6 ps at a relatively low repetition rate of ~7.9 MHz, with a signal-to-noise ratio of ~69 dB. To characterize the short-term stability of the obtained regime, we have measured the relative intensity noise of the laser, which is <−107 dBc/Hz in the range of 3 Hz–1000 kHz. It should be noted that the standard deviation of root mean square of average power does not exceed a magnitude of 0.9% for 3 h of measurement. Full article

(This article belongs to the Special Issue Fiber Laser Sources)

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10 pages, 3159 KiB

Open AccessArticle

The Effect of Laser Nitriding on Surface Characteristics and Wear Resistance of NiTi Alloy with Low Power Fiber Laser

by Hao Wang, Ralf Nett, Evgeny L. Gurevich and Andreas Ostendorf

Appl. Sci. 2021, 11(2), 515; https://doi.org/10.3390/app11020515 - 7 Jan 2021

Cited by 8 | Viewed by 3640

Abstract

The laser nitriding was performed in nitrogen gas at room temperature (20 °C) and low temperature (−190 °C) by a low power fiber laser to modify the wear and abrasion resistance of NiTi alloy. The surface roughness and element composition were analyzed by [...] Read more.

The laser nitriding was performed in nitrogen gas at room temperature (20 °C) and low temperature (−190 °C) by a low power fiber laser to modify the wear and abrasion resistance of NiTi alloy. The surface roughness and element composition were analyzed by roughness device and energy-dispersive X-ray spectroscopy respectively. The results of roughness show that laser treatment can change the surface roughness due to the laser remelting. The effect of laser nitriding on the microhardness, friction coefficient, and worn scars of NiTi alloy was also studied, which shows that the microhardness of the NiTi alloy increases after laser nitriding. The optical microscope and scanning electron microscope were used to characterize the surface of NiTi alloy after wear testing to observe the microstructure of worn scars. The results show that the laser nitriding with different parameters can induce a nitride layer with different thicknesses and the higher energy deposition is the key factor for the formation of the nitride layer, which can decrease the friction coefficient and reduce wear loss during the application of NiTi alloy. The improvement of wear resistance can be attributed to the hard nitriding layer. Full article

(This article belongs to the Special Issue Laser Manufacturing of Advanced Materials)

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12 pages, 8243 KiB

Open AccessReview

High-Quality, InN-Based, Saturable Absorbers for Ultrafast Laser Development

by Laura Monroy, Marco Jiménez-Rodríguez, Eva Monroy, Miguel González-Herráez and Fernando B. Naranjo

Appl. Sci. 2020, 10(21), 7832; https://doi.org/10.3390/app10217832 - 4 Nov 2020

Cited by 5 | Viewed by 3189

Abstract

New fabrication methods are strongly demanded for the development of thin-film saturable absorbers with improved optical properties (absorption band, modulation depth, nonlinear optical response). In this sense, we investigate the performance of indium nitride (InN) epitaxial layers with low residual carrier concentration (<10 [...] Read more.

New fabrication methods are strongly demanded for the development of thin-film saturable absorbers with improved optical properties (absorption band, modulation depth, nonlinear optical response). In this sense, we investigate the performance of indium nitride (InN) epitaxial layers with low residual carrier concentration (<10¹⁸ cm⁻³), which results in improved performance at telecom wavelengths (1560 nm). These materials have demonstrated a huge modulation depth of 23% and a saturation fluence of 830 µJ/cm², and a large saturable absorption around −3 × 10⁴ cm/GW has been observed, attaining an enhanced, nonlinear change in transmittance. We have studied the use of such InN layers as semiconductor saturable absorber mirrors (SESAMs) for an erbium (Er)-doped fiber laser to perform mode-locking generation at 1560 nm. We demonstrate highly stable, ultrashort (134 fs) pulses with an energy of up to 5.6 nJ. Full article

(This article belongs to the Special Issue Ultrafast Optics: Trends and Prospects)

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Graphical abstract

10 pages, 10781 KiB

Open AccessArticle

The Surface Morphology of a Ti–6Al–4V Fiber-Lasered Nitride Layer

by Jinchang Guo, Yu Shi, Peibiao Geng, Gang Zhang and Ming Zhu

Coatings 2020, 10(5), 451; https://doi.org/10.3390/coatings10050451 - 6 May 2020

Cited by 3 | Viewed by 2306

Abstract

A fiber laser was used to nitride Ti–6Al–4V titanium alloy the effect of the process parameters on the surface morphology was studied. The surface chemical composition of the nitride layer and the phase of black powder on the surface were analyzed, the two-dimensional [...] Read more.

A fiber laser was used to nitride Ti–6Al–4V titanium alloy the effect of the process parameters on the surface morphology was studied. The surface chemical composition of the nitride layer and the phase of black powder on the surface were analyzed, the two-dimensional and three-dimensional surface topography of the nitride layer surface were measured, and the cross-section microstructure of the nitride layer was photographed. The effects of laser power, laser scanning speed, nozzle distance, and nitrogen flow rate on the surface morphology were studied. The experiments show that the laser power mainly affects the surface oxidation, the laser scanning speed mainly affects the surface roughness, and the nozzle distance has a great influence on the surface morphology. The gas flow rate, however, had a slight effect on the surface morphology. A large heat input and a high nitrogen flow rate caused an increase in TiN and TiO₂ black powders. Surface oxidation did not affect the formation of a continuous TiN layer nor surface roughness. Finally, the critical energy density leading to increased surface roughness was calculated. Full article

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17 pages, 4688 KiB

Open AccessArticle

Asymmetry Analysis of the Resonance Curve in Resonant Integrated Optical Gyroscopes

by Yu Ming He, Fu Hua Yang, Wei Yan, Wei Hua Han and Zhao Feng Li

Sensors 2019, 19(15), 3305; https://doi.org/10.3390/s19153305 - 27 Jul 2019

Cited by 7 | Viewed by 3952

Abstract

The Resonant Integrated Optic Gyroscope (RIOG) is a type of high accuracy gyroscope based on the Sagnac effect. A symmetrical resonance curve is very important to the performance of the RIOG. To further investigate and design a RIOG with a waveguide ring resonator, [...] Read more.

The Resonant Integrated Optic Gyroscope (RIOG) is a type of high accuracy gyroscope based on the Sagnac effect. A symmetrical resonance curve is very important to the performance of the RIOG. To further investigate and design a RIOG with a waveguide ring resonator, an in-depth research of the asymmetric resonance curve and its influence on the RIOG is fully developed. Four possible optical noises inducing the resonance curve asymmetry are analyzed and their mathematic models are established. These four optical noises are the normal mode effect, the backscattering noise, the backreflection noise and the polarization noise. Any asymmetry of the resonance curve will not only induce a large output bias error into the gyro output, but also seriously decrease the frequency discrimination parameter of the demodulation curve. By using a tunable fiber laser, the high aspect ratio silicon nitride WRR and the silicon dioxide WRR were tested. The experiment measured resonance curves can be well fitted with the theoretical simulation results. The experimental results show that a high aspect ratio silicon nitride waveguide can effectively suppress the polarization noise in the RIOG. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 407 KiB

Open AccessArticle

Micromachining of AlN and Al₂O₃ Using Fiber Laser

by Florian Preusch, Benedikt Adelmann and Ralf Hellmann

Micromachines 2014, 5(4), 1051-1060; https://doi.org/10.3390/mi5041051 - 10 Nov 2014

Cited by 47 | Viewed by 8762

Abstract

We report on high precision high speed micromachining of Al₂O₃ and AlN using pulsed near infrared fiber laser. Ablation thresholds are determined to be 30 J/cm² for alumina and 18 J/cm² for aluminum nitride. The factors influencing the [...] Read more.

We report on high precision high speed micromachining of Al₂O₃ and AlN using pulsed near infrared fiber laser. Ablation thresholds are determined to be 30 J/cm² for alumina and 18 J/cm² for aluminum nitride. The factors influencing the efficiency and quality of 3D micromachining, namely the surface roughness, the material removal rate and the ablation depth accuracy are determined as a function of laser repetition rate and pulse overlap. Using a fluence of 64 J/cm², we achieve a material removal rate of up to 94 mm³/h in Al₂O₃ and 135 mm³/h in AlN for high pulse overlaps (89% and 84%). A minimum roughness of 1.5 μm for alumina and 1.65 μm for aluminum nitride can be accomplished for medium pulse overlaps (42% to 56%). In addition, ablation depth deviation of the micromachining process of smaller than 8% for alumina and 2% for aluminum nitride are achieved. Based on these results, by structuring exemplarily 3D structures we demonstrate the potential of high quality and efficient 3D micromachining using pulsed fiber laser. Full article

(This article belongs to the Special Issue Laser Micro- and Nano- Processing)

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