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Advanced Lasers and Their Applications
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Advanced Lasers and Their Applications

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

Deadline for manuscript submissions: closed (31 January 2024) | Viewed by 15941

Special Issue Editors

Dr. Song Yang

E-Mail Website
Guest Editor
DTU Electro, Department of Electrical and Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
Interests: fiber laser; mode-locking; Q-switching; nonlinear optics; nano/micro-fabrication; laser imaging; optical sensor
Special Issues, Collections and Topics in MDPI journals
Dr. Yao-Yao Qi

E-Mail Website
Guest Editor
Center for advanced Laser Technology, Hebei University of Technology, Tianjin 300401, China
Interests: fiber laser; mode-locking; all-solid-state laser; visible laser; vortex laser
Dr. Chao-Jian He

E-Mail Website
Guest Editor
Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100081, China
Interests: mode-locking; regenerative amplifier; fiber laser; nonlinear optics; all-solid-state laser

Special Issue Information

Dear Colleagues,

Advanced lasers are highly precise and powerful devices that produce focused beams of light with specific wavelengths and characteristics, which have a wide range of applications and are critical components in many modern technologies. As research and development in laser technology continues, new applications and uses are likely to emerge, such as laser surgery, optic communications, scientific research, remote sensing, laser displays, and so on.

We are inviting both research articles and review papers related to this fascinating topic. Further information can be found on the Special Issue website.

Original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

  • Fiber lasers;
  • All-solid-state lasers;
  • Semiconductor lasers;
  • Mode-locking;
  • Mirco/micro fabrication;
  • Laser imaging;
  • Optical sensor.

We look forward to receiving your contributions.

Dr. Song Yang
Dr. Yao-Yao Qi
Dr. Chao-Jian He
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Photonics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • mode-locking
  • Q-switching
  • high-power laser
  • laser imaging
  • nano-micro fabrication

Related Special Issue

Published Papers (18 papers)

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Research

12 pages, 3376 KiB  
Article
High-Efficiency and Large-Angle Homo-Metagratings for the Near-Infrared Region
by Wei-Cheng Tsai, Chia-Hsun Chang, Tai-Cherng Yu, Yi-Hsuan Huang, Chi-Wai Chow, Yu-Heng Hong, Hao-Chung Kuo and Yao-Wei Huang
Photonics 2024, 11(5), 392; https://doi.org/10.3390/photonics11050392 - 24 Apr 2024
Viewed by 369
Abstract
Compact photonic devices that integrate metasurfaces with light sources have been widely studied. However, experimental demonstrations of a higher efficiency of integration are still lacking. To enhance the efficiency of light sources integrated with metasurfaces, we employed a forward design optimization method and [...] Read more.
Compact photonic devices that integrate metasurfaces with light sources have been widely studied. However, experimental demonstrations of a higher efficiency of integration are still lacking. To enhance the efficiency of light sources integrated with metasurfaces, we employed a forward design optimization method and index matching between the light source and metasurface substrate to design metagratings. To optimize the overall diffraction efficiency, we manipulated the degrees of freedom in phase, the lattice constants, and the number of unit cells. The same material was utilized for the nanostructures and substrate (homo-metagrating) for index matching, while Si and GaAs materials were used for working at 1550 and 940 nm, respectively. The experimental homo-metagratings operating at 1550 nm and made of Si exhibited an overall average efficiency of 51.3% at diffraction angles of 60.3°. On the other hand, experimental homo-metagratings operating at 940 nm and made of GaAs exhibited an overall average efficiency of 52.4% at diffraction angles of 49.3°. This suggests that the future integration of metagratings with a polarization-specific laser can further enhance the overall diffraction efficiency. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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18 pages, 4842 KiB  
Article
Study on Speckle Noise Reduction in Laser Projection Displays
by Hongyou Zhang, Yu Hu, Shuihai Peng and Yong Liu
Photonics 2024, 11(4), 290; https://doi.org/10.3390/photonics11040290 - 22 Mar 2024
Viewed by 623
Abstract
Laser speckle has a negative effect on laser projectors, so reducing laser speckle is crucial for the development of laser projector displays. We primarily focus on studying the laser speckle contrast of laser projector displays and the mechanism for reducing speckle. Based on [...] Read more.
Laser speckle has a negative effect on laser projectors, so reducing laser speckle is crucial for the development of laser projector displays. We primarily focus on studying the laser speckle contrast of laser projector displays and the mechanism for reducing speckle. Based on the theory of decreasing temporal and spatial coherence of laser light, this report derives the complete formula for calculating speckle contrast in a laser projector display and provides detailed calculation procedures. According to the comprehensive formula, the primary factors influencing speckle contrast encompass wavelength, spectrum, angles of incidence or observation of lasers, the roughness of the screen surface, the number of independent speckle patterns generated by a moving diffuser, and the number of resolution elements within one eye resolution element in the projector lens. Various methods have been used in the projection engine to suppress speckle, and the main factors for reducing speckle have been verified through theoretical calculations and experimental verification. At a testing distance of 700 mm and with an F-number of 41.7 for the detector lens, the RGB laser speckle contrasts were measured to be 9.1%, 7.3%, and 10.4%, respectively, which aligns well with the results obtained from theoretical calculations. Meanwhile, the speckle contrast of the white field was also measured, yielding a result of 5.6%. The speckle contrast becomes imperceptible when the viewing distance exceeds 2000 mm in our projection system. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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11 pages, 7221 KiB  
Article
A Theoretical Investigation of an Ultrawide S-, C- and L-Band-Tunable Random Fiber Laser Based on the Combination of Tellurite Fiber and Erbium-Doped Fiber
by Lu Chen, Yang Li, Houkun Liang and Han Wu
Photonics 2024, 11(3), 247; https://doi.org/10.3390/photonics11030247 - 11 Mar 2024
Viewed by 708
Abstract
In this paper, we present a new scheme to generate ultrawide tunable random fiber lasers (RFLs) covering the S-, C- and L-band by combining the broadband Raman gain in tellurite fibers and the active gain in erbium-doped fibers. A numerical simulation based on [...] Read more.
In this paper, we present a new scheme to generate ultrawide tunable random fiber lasers (RFLs) covering the S-, C- and L-band by combining the broadband Raman gain in tellurite fibers and the active gain in erbium-doped fibers. A numerical simulation based on the power-balance model is conducted to verify the feasibility of the ultrawide tunable random fiber lasing generation. Pumped by a 1450 nm laser, the tunable random Raman fiber laser in the ranges of 1480–1560 nm and 1590–1640 nm can only be realized with a tellurite fiber. To further fill in the emission gap in the range of 1560–1590 nm, the erbium-doped fiber is incorporated in the cavity, which can provide efficient erbium-doped gain in the C- and L-band. By combining a 100 m long tellurite fiber and an 8 m long erbium-doped fiber, an ultrawide tunable RFL based on hybrid erbium–Raman gain can be realized with a wavelength tuning range (1480 nm–1640 nm) covering the S-, C- and L-band at 3.5 W pump power. Such a widely tunable RFL is of great importance in applications such as optical communication, sensing and imaging. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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12 pages, 5141 KiB  
Article
Numerical Simulation and Experimental Investigation of ps Pulsed Laser Modification inside 4H-SiC Material
by Yiying Song, Shusen Zhao, Hongzhi He, Han Liang, Zhanfeng Dai, Xuechun Lin and Guling Zhang
Photonics 2024, 11(2), 189; https://doi.org/10.3390/photonics11020189 - 19 Feb 2024
Viewed by 852
Abstract
Silicon Carbide (SiC) is the predominant substrate material for optoelectronic-integrated devices. However, it challenges the wafer-slicing process because of its high hardness, brittleness, and other material characteristics. Laser processing has gained prominence as the primary method, leveraging its merits of high efficiency, precision, [...] Read more.
Silicon Carbide (SiC) is the predominant substrate material for optoelectronic-integrated devices. However, it challenges the wafer-slicing process because of its high hardness, brittleness, and other material characteristics. Laser processing has gained prominence as the primary method, leveraging its merits of high efficiency, precision, and micro-destructiveness. In this study, a finite element method is applied to calculate the temperature field distribution resulting from the electric field of a Gaussian beam. The simulation considers laser propagation inside 4H-SiC, non-linear absorption, and spherical aberration induced by the refractive index of the material. The influence of laser pulse energy and focusing depth are considered. The results indicate that the modification depths decrease with the increasing focusing depth. With the increase of laser pulse energy, the depth of the modification layer increases continuously. Moreover, an experimental setup has been devised to furnish valuable references in validating the proposed model. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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11 pages, 5019 KiB  
Article
The Influence of Spectral Filtering Bandwidth and Laser Gain on the Bound-State Pulse Formation Mechanism and Evolutionary Dynamics in the All-Fiber Mamyshev Oscillator
by Yaoyao Qi, Tianchen Zhang, Zhenxu Bai, Jie Ding, Bingzheng Yan, Yulei Wang, Zhiwei Lu and Dapeng Yan
Photonics 2024, 11(2), 139; https://doi.org/10.3390/photonics11020139 - 01 Feb 2024
Viewed by 716
Abstract
We present a numerical investigation of the bound-state pulse formation mechanism and evolutionary dynamics based on the pump strength and spectral filtering bandwidth in the all-fiber Mamyshev oscillator. Through the numerical simulation and analysis, the different mode-locked pulses’ (such as single pulses, bound-state [...] Read more.
We present a numerical investigation of the bound-state pulse formation mechanism and evolutionary dynamics based on the pump strength and spectral filtering bandwidth in the all-fiber Mamyshev oscillator. Through the numerical simulation and analysis, the different mode-locked pulses’ (such as single pulses, bound-state pulses, and chaotic multi-pulses) regime transformation conditions are quantified. The results suggest that with an increase in the pump strength, the sub-pulse energy and output coupler of the Mamyshev oscillator show an inverse proportion trend, which plays an important role in increasing the number of sub-pulses in the bound-state pulses’ state. Furthermore, optimization schemes, such as adjusting the filter bandwidth and slowing down the accumulation of nonlinear effects, are proposed to achieve a high-energy pulse output in the Mamyshev oscillator. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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14 pages, 6746 KiB  
Article
Fully Phase-Locked Fiber Dual Comb Enables Accurate Frequency and Phase Detection in Multidimensional Coherent Spectroscopy
by Shiping Xiong, Zejiang Deng, Zhong Zuo, Jiayi Pan, Zilin Zhao, Gehui Xie and Wenxue Li
Photonics 2024, 11(2), 120; https://doi.org/10.3390/photonics11020120 - 28 Jan 2024
Viewed by 862
Abstract
High-resolution optical multidimensional coherent spectroscopy (MDCS) requires frequency-stable laser sources and high-resolution heterodyne spectra. Fully phase-locked dual-comb spectroscopy (DCS) enables the achievement of high resolution, high accuracy, broad bandwidth, and a rapid multi-heterodyne spectrum, which results in the DCS’s potential to replace the [...] Read more.
High-resolution optical multidimensional coherent spectroscopy (MDCS) requires frequency-stable laser sources and high-resolution heterodyne spectra. Fully phase-locked dual-comb spectroscopy (DCS) enables the achievement of high resolution, high accuracy, broad bandwidth, and a rapid multi-heterodyne spectrum, which results in the DCS’s potential to replace the spectrometer and phase detection system in MDCS. We verified the phase measurement capability of the MDCS system based on fully phase-locked fiber DCS by studying phase-sensitive photon echoes and double-quantum processes. The accurate phase and frequency of linear and nonlinear signals were obtained simultaneously using a single detector without subsequent frequency drift correction. Subsequently, the acquisition of longtime quantum beat signals demonstrates the high phase coherence between excitation pulses. Additionally, the two-dimensional coherent spectrum (2DCS) with high signal-to-noise-ratio and 100 MHz resolution was obtained via the MDCS system based on fully phase-locked fiber DCS. These results exhibit that fully phase-locked fiber DCS is an effective method for high-resolution 2DCS measurement, which facilitates further research on cold atoms, higher-order nonlinear spectra, and molecular fingerprint vibrational spectroscopy. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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10 pages, 2799 KiB  
Article
Analysis of High-Order Surface Gratings Based on Micron Lasers on Silicon
by Jiachen Tian, Licheng Chen, Xuliang Zhou, Hongyan Yu, Yejin Zhang and Jiaoqing Pan
Photonics 2024, 11(1), 92; https://doi.org/10.3390/photonics11010092 - 19 Jan 2024
Viewed by 771
Abstract
High-quality silicon-based lasers are necessary to achieve full integration of photonic and electronic circuits. Monolithic integration of III–Vmicron lasers on silicon by means of the aspect ratio trapping (ART) method is a promising solution. To obtain sufficient optical feedback to excite the laser [...] Read more.
High-quality silicon-based lasers are necessary to achieve full integration of photonic and electronic circuits. Monolithic integration of III–Vmicron lasers on silicon by means of the aspect ratio trapping (ART) method is a promising solution. To obtain sufficient optical feedback to excite the laser without introducing complex fabricating processes, we have designed a high-order surface grating on micron lasers which was epitaxially grown by the ART method and can be fabricated by common UV lithography. The performance of the grating was analyzed by the finite-difference time-domain (FDTD) method and eigenmode expansion (EME) solver. After simulation optimization, the etching depth was set to 0.6 μm to obtain proper reflection. The width of the slots and the slot spacing were selected to be 1.12 μm and 5.59 μm, respectively. Finally, we obtained results of 4% reflectance and 82% transmittance at a 1.55 μm wavelength at 24 periods. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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13 pages, 6529 KiB  
Article
The Development of a Remote Edge-Lit Backlight Structure with Blue Laser Diodes
by Bing-Mau Chen, Shang-Ping Ying, Truong An Pham, Shiuan-Yu Tseng and Yu-Kang Chang
Photonics 2024, 11(1), 78; https://doi.org/10.3390/photonics11010078 - 15 Jan 2024
Viewed by 790
Abstract
In this study, we introduce a novel design of a remote edge-lit backlight structure featuring blue laser diodes (LDs). These LDs were integrated into a remote yellow phosphor layer on a light guide plate (LGP). Blue light emitted by the LDs passes through [...] Read more.
In this study, we introduce a novel design of a remote edge-lit backlight structure featuring blue laser diodes (LDs). These LDs were integrated into a remote yellow phosphor layer on a light guide plate (LGP). Blue light emitted by the LDs passes through the LGP and spreads to the remote phosphor layer, generating white light output. Owing to the incorporation of a scattering layer between sequential LGPs, the remote edge-lit backlight structure facilitates the expansion of the output surface of the LGP by combining multiple individual LGPs. Two- and three-LGP remote edge-lit backlight structures demonstrated acceptable white illuminance uniformity. The proposed architecture serves as a viable solution for achieving uniform illumination in planar lighting systems using blue LDs; thus, this structure is particularly suitable for linear lighting or slender backlighting instead of display stand applications. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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16 pages, 3254 KiB  
Article
Sub-Nanosecond, High Peak Power Yb:YAG/Cr4+:YAG/YVO4 Passively Q-Switched Raman Microchip Laser with the Emission of Multiple Pulses
by Xiaolei Wang, Chaoyi Zhang, Yanlu Zhang, Shengying Fan, Xinqiang Ma and Wei Cheng
Photonics 2024, 11(1), 61; https://doi.org/10.3390/photonics11010061 - 05 Jan 2024
Viewed by 779
Abstract
This paper demonstrates the capability of sub-nanosecond, high peak power Yb:YAG/Cr4+:YAG/YVO4 passively Q-switched Raman microchip lasers at 1134 nm operated in multiple pulses mode under quasi-continuous-wave (QCW) pumping. Total pulse energy for the Stokes laser was 1.8 mJ with a [...] Read more.
This paper demonstrates the capability of sub-nanosecond, high peak power Yb:YAG/Cr4+:YAG/YVO4 passively Q-switched Raman microchip lasers at 1134 nm operated in multiple pulses mode under quasi-continuous-wave (QCW) pumping. Total pulse energy for the Stokes laser was 1.8 mJ with a 4 mm YVO4 crystal and TOC = 16%. The corresponding pulse repetition rate reached 225 kHz within a single pumping pulse. By employing a compact plane-concave cavity and 5 mm YVO4 crystal, the single pulse energy for the Raman laser was further scaled up to 44 μJ. The corresponding peak power was 95 kW. A highest output pulse repetition rate of 87.8 kHz and shortest pulse duration of 464 ps were found for the Raman laser. The results indicate that the Raman microchip laser configuration under QCW LD pumping is a promising approach for developing high peak power, commercial and portable Raman lasers with a pulse duration of several hundred-picoseconds at a pulse repetition rate of hundred kilohertz. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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13 pages, 4104 KiB  
Article
Nonlinear Scattering of 248 nm Wavelength Light in High-Pressure SF6 and CH4 Gases for the Temporal Compression of a 20 ns KrF Laser Pulse
by Vladimir D. Zvorykin, Gocha E. Metreveli, Igor’ V. Smetanin, Alexey V. Shutov, Nikolay N. Ustinovskii and Polad V. Veliev
Photonics 2024, 11(1), 39; https://doi.org/10.3390/photonics11010039 - 30 Dec 2023
Viewed by 739
Abstract
The nonlinear compression of narrowband (Δν ≈ 0.2 cm−1) 20 ns KrF laser pulses in SF6 at 10 atm and in CH4 at 50 atm pressure was studied. Both SBS and SRS optically phase-conjugated backward-reflected radiation was registered [...] Read more.
The nonlinear compression of narrowband (Δν ≈ 0.2 cm−1) 20 ns KrF laser pulses in SF6 at 10 atm and in CH4 at 50 atm pressure was studied. Both SBS and SRS optically phase-conjugated backward-reflected radiation was registered with an energy reflectivity of 10–14% in SF6 and CH4. In SF6, the SBS pulses gradually shortened from 10 ns to 2–3 ns with a decrease in pumping to the SBS threshold of ~10 mJ, while the SRS pulse had the shortest length of 30–60 ps for the maximal pumping of 120 mJ and broadened near the SRS threshold of ~30 mJ. For the SRS pulse energy, the ~2 mJ peak power 5 × 107 W was tenfold higher than the pump power. The theoretical model predicted a soliton-like SRS pulse compression to a temporal length of the order of the vibrational relaxation time. There was no pulse compression of backward SBS and SRS radiation in CH4, while, in the forward direction, SRS pulses shortened to 3–4 ns at reduced pumping. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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11 pages, 2611 KiB  
Article
CVD Encapsulation of Laser-Graphitized Electrodes in Diamond Electro-Optical Devices
by Maxim S. Komlenok, Vitali V. Kononenko, Andrey P. Bolshakov, Nikolay D. Kurochitskiy, Dmitrii G. Pasternak, Alexander A. Ushakov and Vitaly I. Konov
Photonics 2024, 11(1), 10; https://doi.org/10.3390/photonics11010010 - 23 Dec 2023
Viewed by 1072
Abstract
Conductive graphitized grooves on the dielectric surface of diamond have been created by KrF excimer laser radiation. The advantages of such a circuit board in high-field applications is rather limited because the crystal surface has a relatively low electrical breakdown threshold. To increase [...] Read more.
Conductive graphitized grooves on the dielectric surface of diamond have been created by KrF excimer laser radiation. The advantages of such a circuit board in high-field applications is rather limited because the crystal surface has a relatively low electrical breakdown threshold. To increase the electrical strength, a method of encapsulating surface conductive graphitized structures by chemical vapor deposition of an epitaxial diamond layer has been proposed and realized. The quality of the growth diamond is proved by Raman spectroscopy. A comparative study of the electrical resistivity of graphitized wires and the breakdown fields between them before and after diamond growth was carried out. The proposed technique is crucial for diamond-based high-field electro-optical devices, such as THz photoconductive emitters. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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12 pages, 2164 KiB  
Article
Prompt Analysis and Design for Passively Mode-Locked Solid-State Lasers with Semiconductor Saturable Absorbers
by Pin-Wen Cheng, Yu-Hsin Hsu, Hsing-Chih Liang, Kai-Feng Huang and Yung-Fu Chen
Photonics 2024, 11(1), 8; https://doi.org/10.3390/photonics11010008 - 22 Dec 2023
Viewed by 823
Abstract
The critical pump power for achieving passively continuous-wave mode-locking in a solid-state laser is analytically derived from the spatially dependent rate equations and the criterion for the intracavity pulse energy. A prompt way is proposed to straightforwardly design the cavity for passively mode-locked [...] Read more.
The critical pump power for achieving passively continuous-wave mode-locking in a solid-state laser is analytically derived from the spatially dependent rate equations and the criterion for the intracavity pulse energy. A prompt way is proposed to straightforwardly design the cavity for passively mode-locked solid-state lasers. Complete experiments are performed to demonstrate the proposed cavity design and, simultaneously, to verify the theoretical model for the critical pump powers. It is interestingly observed that even though a larger modulation depth causes a higher critical pump power, it can generate a shorter pulse width in return. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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15 pages, 9268 KiB  
Article
Tailoring the Direct Current Modulation Response of Electrically Pumped Semiconductor Nano-Laser Arrays
by Yuanlong Fan, Siyi An, K. Alan Shore and Xiaopeng Shao
Photonics 2023, 10(12), 1373; https://doi.org/10.3390/photonics10121373 - 14 Dec 2023
Viewed by 895
Abstract
Semiconductor nano-lasers have been a topic of interest from the perspective of advancing the capabilities of photonic integration. Nano-lasers are perceived as the means to achieve improved functionality in photonic integrated circuits. The properties and performance of nano-lasers have been examined by means [...] Read more.
Semiconductor nano-lasers have been a topic of interest from the perspective of advancing the capabilities of photonic integration. Nano-lasers are perceived as the means to achieve improved functionality in photonic integrated circuits. The properties and performance of nano-lasers have been examined by means of simulations and laboratory measurements. Nano-lasers lend themselves to integration to form dense arrays in both one and two dimensions. In a recent work, a theoretical treatment was presented for the dynamic behaviour of stand-alone electrically pumped nano-laser arrays. In this work, the response of nano-laser arrays to direct current modulation is examined. As in previous works, attention is given to two prototype array geometries: a linear three-element linear array and an equilateral triangular array. Large one-dimensional arrays can be built by repeating this elementary linear array. Two-dimensional photonic integrated circuits can incorporate the triangular arrays studied here. Such prototypical configurations offer opportunities to tailor the modulation response of the nano-laser arrays. The principal factors which provide that capability are the coupling strengths between lasers in the arrays and the direct modulation parameters. The former are fixed at the design and manufacture stage of the array whilst the latter can be chosen. In addition, the enhancement of the spontaneous emission rate via the so-called Purcell effect in nano-lasers offers a device-specific means for accessing a range of modulation responses. Two-dimensional portraits of the regimes of differing modulation responses offer a convenient means for determining the dynamics that may be accessed by varying the laser drive current. It is shown by these means that a rich variety of modulation responses can be accessed in both linear and triangular arrays. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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13 pages, 2810 KiB  
Article
Terahertz Generation through Coherent Excitation of Slow Surface Waves in an Array of Carbon Nanotubes
by Sergey A. Afanas’ev, Andrei A. Fotiadi, Aleksei S. Kadochkin, Evgeny P. Kitsyuk, Sergey G. Moiseev, Dmitry G. Sannikov, Vyacheslav V. Svetukhin, Yury P. Shaman and Igor O. Zolotovskii
Photonics 2023, 10(12), 1317; https://doi.org/10.3390/photonics10121317 - 29 Nov 2023
Viewed by 929
Abstract
In this paper, we present a scheme for generating terahertz (THz) radiation using an array of parallel double-walled carbon nanotubes (DWCNTs) subjected to a direct current (DC). The longitudinal surface plasmon polaritons (SPPs) in the DWCNTs are coherently excited by two near-infrared laser [...] Read more.
In this paper, we present a scheme for generating terahertz (THz) radiation using an array of parallel double-walled carbon nanotubes (DWCNTs) subjected to a direct current (DC). The longitudinal surface plasmon polaritons (SPPs) in the DWCNTs are coherently excited by two near-infrared laser beams with slightly different frequencies. Through numerical methods, we investigate the spectral characteristics of the SPPs in the presence of a DC current in the nanotubes. We identify high-quality plasmonic modes with a slowdown factor exceeding 300 in the terahertz frequency region. The amplification of these slow SPP modes is facilitated by the DC current in the DWCNTs, fulfilling a synchronism condition. This condition ensures that the phase velocity of the SPPs is closely matched to the drift velocity of the charge carriers, allowing for an efficient energy exchange between the current and the surface electromagnetic wave. The high-frequency currents on the nanotube walls in the DWCNT array enable the emission of THz radiation into the far field, owing to an antenna effect. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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10 pages, 5336 KiB  
Article
Dynamics of Electrically Pumped Semiconductor Nano-Laser Arrays
by Yuanlong Fan, K. Alan Shore and Xiaopeng Shao
Photonics 2023, 10(11), 1249; https://doi.org/10.3390/photonics10111249 - 10 Nov 2023
Cited by 1 | Viewed by 792
Abstract
Semiconductor nano-lasers have been actively investigated both theoretically and experimentally with to the aim of providing a highly compact laser amenable to photonic integration. Such devices are naturally suited for assembly in close-packed one- and two-dimensional arrays. In such arrangements, optical coupling between [...] Read more.
Semiconductor nano-lasers have been actively investigated both theoretically and experimentally with to the aim of providing a highly compact laser amenable to photonic integration. Such devices are naturally suited for assembly in close-packed one- and two-dimensional arrays. In such arrangements, optical coupling between elements of the array opens opportunities to generate a range of dynamical behaviours. In this paper, we present the first theoretical treatment of the dynamics of electrically pumped nano-laser arrays. Two specific forms of such arrays are analysed in detail: a three-element linear array, and triangular arrays. The former is the basis for extensive one-dimensional arrays, whilst the latter is a building block of many possible geometric configurations of two-dimensional nanolaser arrays. Using these prototypical configurations enables the identification of novel dynamical behaviours, which may be accessed using nano-laser arrays. A distinguishing physical feature of nano-lasers is the enhancement of the spontaneous emission rate via the so-called Purcell effect. Allowing for a range of Purcell enhancement factors, the analysis focusses on the effects of experimentally controllable parameters such as the laser drive current. It is shown that the Purcell enhancement factor is critical to the availability of a range of dynamical behaviours which arise simply due to inter-element optical coupling. Two-dimensional portraits of the regimes of differing dynamics offer a convenient means for determining the dynamics which may be accessed by varying the laser drive current. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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10 pages, 2335 KiB  
Article
132 W 132 μJ Femtosecond Pulses from a Coherently Combined System of Two Rod-Type Photonic Crystal Fibers
by Gehui Xie, Daping Luo, Zhenqiang Tang, Zejiang Deng, Lian Zhou, Jiayi Pan, Chenglin Gu, Can Li, Yang Liu, Jinyong Leng, Pu Zhou and Wenxue Li
Photonics 2023, 10(10), 1138; https://doi.org/10.3390/photonics10101138 - 11 Oct 2023
Viewed by 1217
Abstract
A coherent beam combination has the potential to revolutionize high-peak-power laser systems. However, achieving a high-average-power ultrashort pulse is difficult due to the accumulation of a nonlinear phase and gain narrowing. In this article, we demonstrate a coherent beam combination system that does [...] Read more.
A coherent beam combination has the potential to revolutionize high-peak-power laser systems. However, achieving a high-average-power ultrashort pulse is difficult due to the accumulation of a nonlinear phase and gain narrowing. In this article, we demonstrate a coherent beam combination system that does not require pulse shaping or a spectral modulator. By optimizing the gain of each amplifier and using highly integrated optical components, we reduce the limitations caused by the accumulation of a nonlinear phase and gain narrowing. In our study, we used a polarization beam splitter to combine the pulses from two rod-type photonic crystal fibers (PCFs) in a Mach–Zehnder-type interferometer. A piezo-mounted mirror controlled with a Hänsch–Couillaud polarization detecting system was used to stabilize active phase locking. The system produces 165 W with a 91.6% combining efficiency compared to 90 W per amplifier. Compressed pulses with an energy of 132 µJ and Gaussian fitting pulse duration of 330 fs were achieved. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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17 pages, 6112 KiB  
Article
Femtosecond Laser Fabrication of Silver Microstructures in Nanoporous Glasses
by A. O. Rybaltovsky, E. O. Epifanov, V. N. Sigaev, S. S. Fedotov, V. I. Yusupov and N. V. Minaev
Photonics 2023, 10(9), 1055; https://doi.org/10.3390/photonics10091055 - 16 Sep 2023
Viewed by 877
Abstract
This paper presents the results of studying the process of laser formation of microstructures from silver nanoparticles in nanoporous quartz glasses. Glass samples were impregnated with organometallic molecules Ag(hfac)COD in a supercritical carbon dioxide environment. The formation of point and linear microstructures was [...] Read more.
This paper presents the results of studying the process of laser formation of microstructures from silver nanoparticles in nanoporous quartz glasses. Glass samples were impregnated with organometallic molecules Ag(hfac)COD in a supercritical carbon dioxide environment. The formation of point and linear microstructures was carried out by high-frequency (70 MHz) femtosecond laser radiation with a wavelength of 525 nm and energy in the pulse up to 1 nJ. It was found that the formation of microstructures occurs due to photo- and thermal decomposition of precursor molecules with the formation of plasmonic silver nanoparticles. It is shown that the developed temperatures can exceed the melting point of glass, which leads to the appearance of microstructures with altered refractive index. A qualitative model explaining the individual stages of cluster formation in the glass volume under point laser impact is presented. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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12 pages, 3281 KiB  
Article
Stable Emissions from a Four-Rod Nd:YAG Solar Laser with ±0.5° Tracking Error Compensation Capacity
by Miguel Catela, Dawei Liang, Joana Almeida, Hugo Costa, Dário Garcia, Bruno D. Tibúrcio, Emmanuel Guillot and Cláudia R. Vistas
Photonics 2023, 10(9), 1047; https://doi.org/10.3390/photonics10091047 - 14 Sep 2023
Viewed by 875
Abstract
Conventional solar-pumped lasers rely on expensive and highly accurate solar tracking systems, which present a significant economic barrier to both solar laser research and practical applications. To address this challenge, an end-side-pumped four-rod solar laser head was designed and built for testing at [...] Read more.
Conventional solar-pumped lasers rely on expensive and highly accurate solar tracking systems, which present a significant economic barrier to both solar laser research and practical applications. To address this challenge, an end-side-pumped four-rod solar laser head was designed and built for testing at PROMES-CNRS. Solar radiation was collected and concentrated using a heliostat–parabolic mirror system. A fused silica aspheric lens further concentrated the solar rays into a flux homogenizer within which four Nd:YAG rods were symmetrically positioned around a reflective cone and cooled by water. Four partially reflective mirrors were precisely aligned to extract continuous-wave 1064 nm solar laser power from each laser rod. The prototype demonstrated stable multibeam solar laser operation with the solar tracking system turned on. Even when the tracking system was turned off, the total output power extracted from the solar-pumped laser remained stable for 1 min, representing, to the best of our knowledge, the first successful demonstration of a stable multibeam solar laser operation without solar tracking. For typical solar tracking errors up to ±0.5°, the loss in the total solar laser power produced was only about 1%, representing an 8.0-fold improvement over the previous solar laser experiments under tracking error conditions. Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications)
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