Photonics

Research

12 pages, 3376 KiB

Open AccessArticle

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 2634

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)

► Show Figures

Figure 1

18 pages, 4842 KiB

Open AccessArticle

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

Cited by 2 | Viewed by 1475

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)

► Show Figures

Figure 1

11 pages, 7221 KiB

Open AccessArticle

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 1208

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)

► Show Figures

Figure 1

12 pages, 5141 KiB

Open AccessArticle

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

Cited by 1 | Viewed by 1827

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)

► Show Figures

Figure 1

11 pages, 5019 KiB

Open AccessArticle

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 - 1 Feb 2024

Cited by 2 | Viewed by 1290

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)

► Show Figures

Figure 1

14 pages, 6746 KiB

Open AccessArticle

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 1447

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)

► Show Figures

Figure 1

10 pages, 2799 KiB

Open AccessArticle

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 1244

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)

► Show Figures

Figure 1

13 pages, 6529 KiB

Open AccessArticle

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 1301

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)

► Show Figures

Figure 1

16 pages, 3254 KiB

Open AccessArticle

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 - 5 Jan 2024

Cited by 1 | Viewed by 1303

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 T_OC = 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)

► Show Figures

Figure 1

13 pages, 4104 KiB

Open AccessArticle

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 1193

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)

► Show Figures

Figure 1

11 pages, 2611 KiB

Open AccessArticle

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 1489

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)

► Show Figures

Figure 1

12 pages, 2164 KiB

Open AccessArticle

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 1233

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)

► Show Figures

Figure 1

15 pages, 9268 KiB

Open AccessArticle

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

Cited by 1 | Viewed by 1293

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)

► Show Figures

Figure 1

13 pages, 2810 KiB

Open AccessArticle

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

Cited by 1 | Viewed by 1414

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)

► Show Figures

Figure 1

10 pages, 5336 KiB

Open AccessArticle

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 3 | Viewed by 1194

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)

► Show Figures

Figure 1

10 pages, 2335 KiB

Open AccessArticle

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

Cited by 3 | Viewed by 1767

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)

► Show Figures

Figure 1

17 pages, 6112 KiB

Open AccessArticle

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

Cited by 1 | Viewed by 1235

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)

► Show Figures

Figure 1

12 pages, 3281 KiB

Open AccessArticle

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

Cited by 3 | Viewed by 1543

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)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Advanced Lasers and Their Applications

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Related Special Issue

Published Papers (18 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI