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2 pages, 164 KiB

Open AccessEditorial

Non-Linear Optical Effects in Nanomaterials

by Jaroslaw Mysliwiec

Nanomaterials 2019, 9(12), 1717; https://doi.org/10.3390/nano9121717 - 02 Dec 2019

Viewed by 1879

Abstract

Nonlinear optics is the domain of optics that studies the physical interaction between one or multiple optical beams of high intensity and an optical medium [...] Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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12 pages, 2521 KiB

Open AccessArticle

Improved Laser Damage Threshold of In₂Se₃ Saturable Absorber by PVD for High-Power Mode-Locked Er-Doped Fiber Laser

by Xile Han, Huanian Zhang, Shouzhen Jiang, Chao Zhang, Dengwang Li, Quanxin Guo, Jinjuan Gao and Baoyuan Man

Nanomaterials 2019, 9(9), 1216; https://doi.org/10.3390/nano9091216 - 28 Aug 2019

Cited by 28 | Viewed by 3633

Abstract

In this study, a double-end pumped high-power passively mode-locked erbium-doped fiber laser (EDFL) was realized by employing a few-layered In₂Se₃ flakes as a saturable absorber (SA). Herein, the uniform large-scale In₂Se₃ flakes were synthesized by the physical [...] Read more.

In this study, a double-end pumped high-power passively mode-locked erbium-doped fiber laser (EDFL) was realized by employing a few-layered In₂Se₃ flakes as a saturable absorber (SA). Herein, the uniform large-scale In₂Se₃ flakes were synthesized by the physical vapor deposition (PVD) method. The PVD-In₂Se₃ SA exhibited a remarkable damage threshold of higher than 24 mJ/cm². Meanwhile, the PVD-In₂Se₃ SA had a modulation depth and saturable intensity of 18.75% and 6.8 MW/cm², respectively. Based on the In₂Se₃ SA, the stable bright pulses emitting at 1559.4 nm with an average output power/pulse energy/pulse duration of 122.4 mW/5.8 nJ/14.4 ns were obtained successfully. To our knowledge, 122.4 mW was the new major breakthrough of mode-locked Er-doped fiber lasers. In addition, this is the first demonstration of the dark-bright pulse pair generation based on In₂Se₃ SA. The maximum average output power of the dark-bright pulse reached 121.2 mW, which also showed significant enhancement in comparison with previous works. Our excellent experiment results fully prove the superiority of our experimental design scheme and indicate that the PVD-In₂Se₃ could operate as a promising highly-nonlinear photonic material for a high-power fiber laser. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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10 pages, 2601 KiB

Open AccessArticle

Near-Infrared Optical Modulation for Ultrashort Pulse Generation Employing Indium Monosulfide (InS) Two-Dimensional Semiconductor Nanocrystals

by Tao Wang, Jin Wang, Jian Wu, Pengfei Ma, Rongtao Su, Yanxing Ma and Pu Zhou

Nanomaterials 2019, 9(6), 865; https://doi.org/10.3390/nano9060865 - 07 Jun 2019

Cited by 15 | Viewed by 2987

Abstract

In recent years, metal chalcogenide nanomaterials have received much attention in the field of ultrafast lasers due to their unique band-gap characteristic and excellent optical properties. In this work, two-dimensional (2D) indium monosulfide (InS) nanosheets were synthesized through a modified liquid-phase exfoliation method. [...] Read more.

In recent years, metal chalcogenide nanomaterials have received much attention in the field of ultrafast lasers due to their unique band-gap characteristic and excellent optical properties. In this work, two-dimensional (2D) indium monosulfide (InS) nanosheets were synthesized through a modified liquid-phase exfoliation method. In addition, a film-type InS-polyvinyl alcohol (PVA) saturable absorber (SA) was prepared as an optical modulator to generate ultrashort pulses. The nonlinear properties of the InS-PVA SA were systematically investigated. The modulation depth and saturation intensity of the InS-SA were 5.7% and 6.79 MW/cm², respectively. By employing this InS-PVA SA, a stable, passively mode-locked Yb-doped fiber laser was demonstrated. At the fundamental frequency, the laser operated at 1.02 MHz, with a pulse width of 486.7 ps, and the maximum output power was 1.91 mW. By adjusting the polarization states in the cavity, harmonic mode-locked phenomena were also observed. To our knowledge, this is the first time an ultrashort pulse output based on InS has been achieved. The experimental findings indicate that InS is a viable candidate in the field of ultrafast lasers due to its excellent saturable absorption characteristics, which thereby promotes the ultrafast optical applications of InX (X = S, Se, and Te) and expands the category of new SAs. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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10 pages, 3752 KiB

Open AccessArticle

Nonlinear Absorption Properties of Cr₂Ge₂Te₆ and Its Application as an Ultra-Fast Optical Modulator

by Peng-fei Ma, Wei Lin, Hua-nian Zhang, Shan-hui Xu and Zhong-min Yang

Nanomaterials 2019, 9(5), 789; https://doi.org/10.3390/nano9050789 - 23 May 2019

Cited by 27 | Viewed by 3693

Abstract

In this manuscript, the nonlinear absorption properties of Cr₂Ge₂Te₆ and its application in ultra-fast optical modulation are investigated. Typical parameters, namely, nonlinear absorption coefficient (β), saturation intensity, and modulation depth are measured to be ~1.66 × 10⁻⁹ [...] Read more.

In this manuscript, the nonlinear absorption properties of Cr₂Ge₂Te₆ and its application in ultra-fast optical modulation are investigated. Typical parameters, namely, nonlinear absorption coefficient (β), saturation intensity, and modulation depth are measured to be ~1.66 × 10⁻⁹ m/W, 15.3 MW/cm², and 5.8%, respectively. To investigate the feasibility of using the Cr₂Ge₂Te₆ as an ultra-fast optical modulator, a ring-cavity passively mode-locked Er-doped fiber laser has been constructed. The output power/pulse, duration/pulse, and repetition rate/signal-to-noise ratios for the stable mode-locked operation are 2.88 mW/881 fs/19.33 MHz/48 dB, respectively, which proves that the Cr₂Ge₂Te₆ has outstanding nonlinear optical properties and advantages in performing as an ultra-fast optical modulator. Further, the experimental results provide valuable references and open new avenues for developing two-dimensional, material-based, ultra-fast optical modulators and advanced photonic devices based on Cr₂Ge₂Te₆. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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16 pages, 3894 KiB

Open AccessArticle

Effects of Different TiO₂ Particle Sizes on the Microstructure and Optical Limiting Properties of TiO₂/Reduced Graphene Oxide Nanocomposites

by Yuyu Ren, Lili Zhao, Yang Zou, Lixin Song, Ningning Dong and Jun Wang

Nanomaterials 2019, 9(5), 730; https://doi.org/10.3390/nano9050730 - 11 May 2019

Cited by 16 | Viewed by 3351

Abstract

TiO₂/reduced graphene oxide (rGO) nanocomposites with two different TiO₂ particle sizes were synthesized by a facile hydrothermal method using two different source materials of Ti: tetrabutyl titanate (TBT) and commercial TiO₂ powder (P25). For respective series with the same [...] Read more.

TiO₂/reduced graphene oxide (rGO) nanocomposites with two different TiO₂ particle sizes were synthesized by a facile hydrothermal method using two different source materials of Ti: tetrabutyl titanate (TBT) and commercial TiO₂ powder (P25). For respective series with the same source materials, we investigated additions that optimized the nonlinear optical properties (NLO) and optical limiting (OL) performances, and we explored the relationships between structural diversity and performance. Several characterization techniques, including X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and diffuse reflectance ultraviolet-visible spectroscopy (UV-Vis) were conducted to confirm the microstructures and chemical states of as-prepared materials. This indicated the existence of the Ti–O–C bond between rGO sheets and TiO₂ particles and the reduction from precursor graphene oxide (GO) to rGO. The results of UV-Vis spectra revealed that the TiO₂/rGO nanocomposites showed smaller band gaps than bare TiO₂. A nanosecond open-aperture Z-scan technique at 1064 nm was applied to investigate NLO and OL properties. TiO₂/rGO nanocomposites exhibited enhanced NLO and OL performances, arising from synergistic effects, compared to individual components. The TBT series samples performed better than the P25 series, presumably relevant to dimensional effects. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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11 pages, 2311 KiB

Open AccessArticle

Versatile Mode-Locked Operations in an Er-Doped Fiber Laser with a Film-Type Indium Tin Oxide Saturable Absorber

by Quanxin Guo, Jie Pan, Dengwang Li, Yiming Shen, Xile Han, Jinjuan Gao, Baoyuan Man, Huanian Zhang and Shouzhen Jiang

Nanomaterials 2019, 9(5), 701; https://doi.org/10.3390/nano9050701 - 05 May 2019

Cited by 29 | Viewed by 3578

Abstract

We demonstrate the generation of versatile mode-locked operations in an Er-doped fiber laser with an indium tin oxide (ITO) saturable absorber (SA). As an epsilon-near-zero material, ITO has been only used to fashion a mode-locked fiber laser as an ITO nanoparticle-polyvinyl alcohol SA. [...] Read more.

We demonstrate the generation of versatile mode-locked operations in an Er-doped fiber laser with an indium tin oxide (ITO) saturable absorber (SA). As an epsilon-near-zero material, ITO has been only used to fashion a mode-locked fiber laser as an ITO nanoparticle-polyvinyl alcohol SA. However, this type of SA cannot work at high power or ensure that the SA materials can be transmitted by the light. Thus, we covered the end face of a fiber with a uniform ITO film using the radio frequency magnetron sputtering technology to fabricate a novel ITO SA. Using this new type of SA, single-wavelength pulses, dual-wavelength pulses, and triple-wavelength multi-pulses were achieved easily. The pulse durations of these mode-locked operations were 1.67, 6.91, and 1 ns, respectively. At the dual-wavelength mode-locked state, the fiber laser could achieve an output power of 2.91 mW and a pulse energy of 1.48 nJ. This study reveals that such a proposed film-type ITO SA has excellent nonlinear absorption properties, which can promote the application of ITO film for ultrafast photonics. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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11 pages, 4325 KiB

Open AccessArticle

Nonlinear Optical Response of Graphene Oxide Langmuir-Blodgett Film as Saturable Absorbers

by Jiang Wang, Yonggang Wang, Taijin Wang, Guangying Li, Rui Lou, Guanghua Cheng and Jing Bai

Nanomaterials 2019, 9(4), 640; https://doi.org/10.3390/nano9040640 - 19 Apr 2019

Cited by 19 | Viewed by 3490

Abstract

Two-dimensional (2D) materials as saturable absorbers (SAs) have attracted intense interest for applications in pulsed laser generation because of their distinguishing optical properties. However, the existing methods of preparing SAs were insufficient. Here, we fabricated graphene oxide (GO) SAs by Langmuir-Blodgett (LB) methods [...] Read more.

Two-dimensional (2D) materials as saturable absorbers (SAs) have attracted intense interest for applications in pulsed laser generation because of their distinguishing optical properties. However, the existing methods of preparing SAs were insufficient. Here, we fabricated graphene oxide (GO) SAs by Langmuir-Blodgett (LB) methods for passively Q-switched Nd:YAG laser. The GO sheets were deposited on a quartz plate using the LB method. Two different LB-GO SAs grown under the surface pressure of 22 and 38 mN/m were obtained. Compared with the drop coating method, LB-GO SA exhibited more excellent uniformity, larger nonlinear performance and higher optical transparency. By inserting LB-GO SA into the Nd:YAG laser linear cavity, the short pulse duration of 156 ns and the average output power of 1.313 W were obtained. The slope efficiency was as high as 43.7%, due to low loss of the LB-GO SA. Our results illustrated a new way for preparing the SA using the LB technique. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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19 pages, 2574 KiB

Open AccessArticle

Complex Dynamics of Photoinduced Mass Transport and Surface Relief Gratings Formation

by Grzegorz Pawlik, Tomasz Wysoczanski and Antoni C. Mitus

Nanomaterials 2019, 9(3), 352; https://doi.org/10.3390/nano9030352 - 04 Mar 2019

Cited by 10 | Viewed by 3095

Abstract

The microscopic and semi-macroscopic mechanisms responsible for photoinduced mass transport in functionalized azo-polymers are far from deeply understood. To get some insight into those mechanisms on “microscopic” scale, we studied the directed photoinduced motion of single functionalized polymer chains under various types of [...] Read more.

The microscopic and semi-macroscopic mechanisms responsible for photoinduced mass transport in functionalized azo-polymers are far from deeply understood. To get some insight into those mechanisms on “microscopic” scale, we studied the directed photoinduced motion of single functionalized polymer chains under various types of polarized light illumination using Monte Carlo bond fluctuation model and our kinetic Monte Carlo model for photoinduced mass transport. We found sub-diffusive, diffusive and super-diffusive regimes of the dynamics of single chains at constant illumination and mostly super-diffusive regime for directed motion in the presence of the gradient of light intensity. This regime is more enhanced for long than for short chains and it approaches the ballistic limit for very long chains. We propose a physical picture of light-driven inscription of Surface Relief Gratings (SRG) as corresponding to a dynamical coexistence of normal and anomalous diffusion in various parts of the system. A simple continuous time random walk model of SRG inscription based on this physical picture reproduced the light-driven mass transport found in experiments as well as the fine structure of SRG. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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10 pages, 5240 KiB

Open AccessArticle

Optical Nonlinearity of ZrS₂ and Applications in Fiber Laser

by Lu Li, Ruidong Lv, Jiang Wang, Zhendong Chen, Huizhong Wang, Sicong Liu, Wei Ren, Wenjun Liu and Yonggang Wang

Nanomaterials 2019, 9(3), 315; https://doi.org/10.3390/nano9030315 - 27 Feb 2019

Cited by 44 | Viewed by 3984

Abstract

Group VIB transition metal dichalcogenides (TMDs) have been successfully demonstrated as saturable absorbers (SAs) for pulsed fiber lasers. For the group comprising IVB TMDs, applications in this field remain unexplored. In this work, ZrS₂-based SA is prepared by depositing a ZrS [...] Read more.

Group VIB transition metal dichalcogenides (TMDs) have been successfully demonstrated as saturable absorbers (SAs) for pulsed fiber lasers. For the group comprising IVB TMDs, applications in this field remain unexplored. In this work, ZrS₂-based SA is prepared by depositing a ZrS₂ nanostructured film onto the side surface of a D-shaped fiber. The nonlinear optical properties of the prepared SA are investigated, which had a modulation depth of 3.3% and a saturable intensity of 13.26 MW/cm². In a pump power range of 144–479 mW, the Er-doped fiber (EDF) laser with ZrS₂ can operate in the dual-wavelength Q-switching state. The pulse duration declined from 10.0 μs down to 2.3 μs. The single pulse energy reached 53.0 nJ. The usage of ZrS₂ as a SA for pulse generation in fiber lasers is presented for the first time. Compared to the experimental results of dual-wavelength Q-switched fiber lasers with two-dimensional (2D) materials, our laser performance was better. Our work indicates that the group comprising IVB TMD ZrS₂ has bright prospects for nonlinear optical applications. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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15 pages, 7488 KiB

Open AccessArticle

Selected Organometallic Compounds for Third Order Nonlinear Optical Application

by Anna Popczyk, Aouatif Aamoum, Anna Migalska-Zalas, Przemyslaw Płóciennik, Anna Zawadzka, Jaroslaw Mysliwiec and Bouchta Sahraoui

Nanomaterials 2019, 9(2), 254; https://doi.org/10.3390/nano9020254 - 13 Feb 2019

Cited by 34 | Viewed by 3825

Abstract

In this paper, we present the third harmonic generation response of Znq₂ (Bis-(8-hydroxyquinolinato)zinc), Cuq₂ (8-Hydroxyquinoline copper(II)), and Alq₃ (Tris-(8-hydroxyquinoline)aluminum) organometallic compounds. An experiment was conducted for s and p polarizations of incident beam, using the Maker fringes technique. The third [...] Read more.

In this paper, we present the third harmonic generation response of Znq₂ (Bis-(8-hydroxyquinolinato)zinc), Cuq₂ (8-Hydroxyquinoline copper(II)), and Alq₃ (Tris-(8-hydroxyquinoline)aluminum) organometallic compounds. An experiment was conducted for s and p polarizations of incident beam, using the Maker fringes technique. The third order nonlinear susceptibility χ⁽³⁾ was estimated using the Kubodera and Kobayashi comparative model, on the grounds that presented compounds exhibit high linear absorption of the generated third harmonic wavelength (355 nm). These complexes were deposited as thin films using the physical vapor deposition (PVD) method. Investigated complexes vary in terms of the coordination center and number of quinoline ligands, which visibly influence their nonlinear response. The global hybrid B3LYP functional with the basis set 6-31G(d) was used in computing the linear and non-linear optical properties. The computed γ_tot value (8765.36 × 10⁻³⁶ esu for Cuq₂) is superior to that of methylene blue (γ = 32.00 × 10⁻³⁶ esu). The calculated theoretical values were found to be in good agreement with the experimental results. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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10 pages, 2803 KiB

Open AccessArticle

Linear and Nonlinear Intersubband Optical Properties of Direct Band Gap GeSn Quantum Dots

by Mourad Baira, Bassem Salem, Niyaz Ahmad Madhar and Bouraoui Ilahi

Nanomaterials 2019, 9(1), 124; https://doi.org/10.3390/nano9010124 - 19 Jan 2019

Cited by 17 | Viewed by 4205

Abstract

Intersubband optical transitions, refractive index changes, and absorption coefficients are numerically driven for direct bandgap strained GeSn/Ge quantum dots. The linear, third-order nonlinear and total, absorption coefficients and refractive index changes are evaluated over useful dot sizes’ range ensuring p-like Γ-electron energy [...] Read more.

Intersubband optical transitions, refractive index changes, and absorption coefficients are numerically driven for direct bandgap strained GeSn/Ge quantum dots. The linear, third-order nonlinear and total, absorption coefficients and refractive index changes are evaluated over useful dot sizes’ range ensuring p-like Γ-electron energy state to be lower than s-like L-electron energy state. The results show strong dependence of the total absorption coefficient and refractive index changes on the quantum dot sizes. The third order nonlinear contribution is found to be sensitive to the incident light intensity affecting both total absorption coefficient and refractive index changes, especially for larger dot sizes. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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10 pages, 2760 KiB

Open AccessArticle

Plasmonic Nanoparticles Driven Enhanced Light Amplification in a Local 2D and 3D Self-Assembly

by Konrad Cyprych, Denis Chateau, Anthony Désert, Stephane Parola and Jaroslaw Mysliwiec

Nanomaterials 2018, 8(12), 1051; https://doi.org/10.3390/nano8121051 - 14 Dec 2018

Cited by 7 | Viewed by 3514

Abstract

We present fluorescence and a random lasing enhancement effect due to the interaction between gold nanoparticles (AuNPs) and Rhodamine 6G (Rh6G) dye. Non-covalently bounded dyes in the proximity of nanoparticles are studied in three systems of varying dimensionality: from (i) three-dimensional freely distributed [...] Read more.

We present fluorescence and a random lasing enhancement effect due to the interaction between gold nanoparticles (AuNPs) and Rhodamine 6G (Rh6G) dye. Non-covalently bounded dyes in the proximity of nanoparticles are studied in three systems of varying dimensionality: from (i) three-dimensional freely distributed suspensions, through (ii) quasi-two-dimensional multilamellar liposomes, to (iii) solid two-dimensional thin layers. Liposomes facilitate the formation of stable AuNPs/Rh6G composition showing enhanced fluorescence, while solid thin films exhibit plasmon-assisted random lasing. Full article

(This article belongs to the Special Issue Non-Linear Optical Effects in Nanomaterials)

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