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15 pages, 22455 KiB

Open AccessArticle

Highly Efficient Cutting of Quartz Glass with Low Roughness and Minor Chipping Using Bessel Laser Beams

by Lei Xiong, Yuhang An, Ling Zhang, Cheng Tang, Tianci Zhang, Aibin Zuo and Wenyan Gao

Photonics 2025, 12(2), 162; https://doi.org/10.3390/photonics12020162 - 18 Feb 2025

Viewed by 352

Abstract

The conventional method of cutting quartz glass with a knife often leads to undesirable effects, such as chipping, debris generation, and an inconsistent cut quality. Additionally, implementing the current methods of laser ablation cutting and crack control cutting presents challenges in ensuring both [...] Read more.

The conventional method of cutting quartz glass with a knife often leads to undesirable effects, such as chipping, debris generation, and an inconsistent cut quality. Additionally, implementing the current methods of laser ablation cutting and crack control cutting presents challenges in ensuring both the quality of the cut and the efficiency of the process. Previous reports have documented a single direct cut of thin quartz glass, albeit at a thickness of only 200 μm. In this study, we utilized a pulse-width-tunable Gaussian beam, in combination with an axicon and a beam-reducing mirror, to generate a high-quality Bessel beam. This process endows the quartz glass with a nano-porous structure with a thickness of 1 mm, enabling high-quality cutting in a single pass. The effects of laser-cutting speed and pulse width on the cutting cross-section and cut surface were investigated. The results of the experiments show that using the optimal cutting speed and pulse width significantly improved cutting quality, reduced surface damage and sputtering, enabled the penetration of the modified cutting cross-section throughout the material, and decreased cutting cross-section roughness to 607 nm Ra. This technique holds promise for the laser-processing industry, enhancing both the quality and efficiency of cutting 1 mm thick quartz glass. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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14 pages, 2467 KiB

Open AccessArticle

Theoretical Comparative Study on the Efficiency of High-Power Long-Distance Laser Power Transmission for Flight Systems

by Songyang Liu, Wenning Xu, Rongqing Tan, Fangjin Ning and Zhiyong Li

Photonics 2025, 12(2), 143; https://doi.org/10.3390/photonics12020143 - 10 Feb 2025

Viewed by 473

Abstract

Wireless power transmission has become a research hotspot in the field of energy transmission, in which laser power transmission is one of the best methods for long-distance wireless transmission. Since laser has the advantages of high directivity, high energy density and no electromagnetic [...] Read more.

Wireless power transmission has become a research hotspot in the field of energy transmission, in which laser power transmission is one of the best methods for long-distance wireless transmission. Since laser has the advantages of high directivity, high energy density and no electromagnetic interference, laser power transmission technology can be applied to the energy supply of unmanned aerial vehicles (UAVs), micro-vehicles, airships and other flight systems. Long-distance laser power transmission can enable high-altitude flight systems to operate continuously without the need to return to the base station for charging, im-proving their operational efficiency. Therefore, high-altitude flight systems have a demand for laser power transmission. However, the commonly used lasers in laser power transmission are semiconductor lasers and fiber lasers, which are only suitable for short-distance transmission of about 1 km. In this paper, taking high-flying UAVs as an example, the transmission efficiency of different lasers used for laser power transmission is analyzed theoretically, and the results show that the diode pumped alkali vapor laser (DPAL) has a high transmission efficiency in high-power long-distance laser power transmission. The transmission efficiency of rubidium lasers which is 1.5 to 4 times that of other lasers can reach 21.94%, which illustrates that DPAL is expected to become a new type of laser source in laser power transmission technology. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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9 pages, 1764 KiB

Open AccessArticle

Tunable Ultraviolet Pulse Generation from a High-Power Self-Similar-Amplification Yb-Fiber Laser

by Zefeng Wang, Daping Luo, Gehui Xie, Zejiang Deng, Chenglin Gu and Wenxue Li

Photonics 2025, 12(1), 50; https://doi.org/10.3390/photonics12010050 - 8 Jan 2025

Viewed by 526

Abstract

A tunable high-power 60 MHz ultraviolet pulse laser directly produced by the extra-cavity fourth-order harmonic generation of a self-similar amplification infrared pulse laser is reported in this study. Utilizing the self-similar pulse evolution and the self-phase modulation in a self-similar amplifier, the system [...] Read more.

A tunable high-power 60 MHz ultraviolet pulse laser directly produced by the extra-cavity fourth-order harmonic generation of a self-similar amplification infrared pulse laser is reported in this study. Utilizing the self-similar pulse evolution and the self-phase modulation in a self-similar amplifier, the system generates a 58.9 W pulse train with a spectral half-width of 85.4 nm, corresponding to a pulse duration of 36 fs. To obtain the ultraviolet pulses from the infrared pulses, a single-pass frequency quadrupling system comprising two cascaded β-BBOs was used. The ultraviolet spectra can be tuned within a spectral range of 253.6 to 275 nm owing to the broadband infrared seed spectra. The maximum ultraviolet average power of 1.44 W was achieved at 275 nm with spectral half-width and an infrared-to-ultraviolet efficiency of 1.1 nm and 2.44%, respectively. To the best of our knowledge, this is the first demonstration of tunable high-power ultraviolet pulse generation from a self-similar amplification Yb-fiber laser. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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13 pages, 1302 KiB

Open AccessArticle

Multidisciplinary Laser Facility Driven by New-Generation High-Repetition Laser

by Gonçalo Vaz, Joana Alves, Victor Hariton, Celso P. João, João Marques, David Cristino, Hugo Gomes, Cara Priebe, Petr Pokorny, Maria P. Santos, Hugo Pires and Gonçalo Figueira

Photonics 2024, 11(12), 1157; https://doi.org/10.3390/photonics11121157 - 9 Dec 2024

Viewed by 764

Abstract

For many years, high-power laser technology has been divided between industrial applications, which prioritize higher average powers and repetition rates, and academic research, which focuses on achieving higher peak powers and ultrashort pulse durations. The introduction of Yb-doped crystals in laser technology has [...] Read more.

For many years, high-power laser technology has been divided between industrial applications, which prioritize higher average powers and repetition rates, and academic research, which focuses on achieving higher peak powers and ultrashort pulse durations. The introduction of Yb-doped crystals in laser technology has paved the way for a new generation of laser sources that bridge the gap between industrial and academic requirements, combining high average power with ultrashort pulse capabilities. These advancements enable the integration of compact, adaptable front-end stages, making such lasers versatile for scientific applications. In Lisbon, the Laboratory of Intense Lasers leverages this technology with a system that combines commercial and custom-built front-end stages to enhance operational flexibility. In this paper, we present the current status of this facility and outline upcoming upgrades. We also showcase applications enabled by these high-power laser sources, including semiconductor studies, bi-photonics, and time-resolved spectroscopy. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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12 pages, 4728 KiB

Open AccessArticle

A Widely and Continuously Tunable Single-Mode Transmitter Based on a Hybrid Microcavity Laser

by Miao-Qing Wang, Bin Zhang, Zhen-Ning Zhang, You-Zeng Hao, Zun-Hao Hu, Yue-De Yang, Jin-Long Xiao, António L. Teixeira and Yong-Zhen Huang

Photonics 2024, 11(11), 1080; https://doi.org/10.3390/photonics11111080 - 17 Nov 2024

Viewed by 796

Abstract

A method for achieving the single-mode and efficient unidirectional emission of a whispering gallery mode (WGM) semiconductor laser is presented herein. Hybrid square-rectangular lasers (HSRLs) and hybrid square/rhombus-rectangular lasers (HSRRLs) consisting of a Fabry–Pérot (FP) cavity and a square or rhombus cavity microcavity [...] Read more.

A method for achieving the single-mode and efficient unidirectional emission of a whispering gallery mode (WGM) semiconductor laser is presented herein. Hybrid square-rectangular lasers (HSRLs) and hybrid square/rhombus-rectangular lasers (HSRRLs) consisting of a Fabry–Pérot (FP) cavity and a square or rhombus cavity microcavity are described. In addition, a transmitter optical subassembly (TOSA) based on an HSRRL chip was fabricated, which has a wide and continuous wavelength tuning range. Wavelength channels from 1555.75 nm to 1568.15 nm with a spacing of 50 GHz were demonstrated with a good side mode suppression ratio (SMSR) and good output power. These devices have the potential to meet the typical requirements of optical communication networks. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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10 pages, 674 KiB

Open AccessArticle

Synchronization Between Kerr Cavity Solitons and Broad Laser Pulse Injection

by Daria A. Dolinina and Andrei G. Vladimirov

Photonics 2024, 11(11), 1050; https://doi.org/10.3390/photonics11111050 - 8 Nov 2024

Viewed by 1053

Abstract

The synchronization of a soliton frequency comb in a Kerr cavity with pulsed laser injection is studied numerically. The neutral delay differential equation is used to model the light dynamics in the cavity. This model allows for the investigation of both cases where [...] Read more.

The synchronization of a soliton frequency comb in a Kerr cavity with pulsed laser injection is studied numerically. The neutral delay differential equation is used to model the light dynamics in the cavity. This model allows for the investigation of both cases where the pulse repetition period is close to the cavity round-trip time and where the repetition period of the injection pulses is close to a rational fraction

M / N

of the round-trip time. It is demonstrated that solitons can exist in this latter case, provided that the injection pulses are of a higher amplitude, which is directly proportional to the number M. Furthermore, it is shown that the synchronization range of the solitons is also proportional to the number M. The solitons excited by pulses with a period slightly different from the M:N-resonance can be destabilized by the Andronov–Hopf bifurcation, which occurs when the injection level at the soliton position decreases to M times the injection amplitude corresponding to the saddle-node bifurcation in a model equation with uniform injection. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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7 pages, 2532 KiB

Open AccessArticle

Combined Efficacy of Q-Switched 785 nm Laser and Tranexamic Acid Cream in the Treatment of Melasma: A Prospective Clinical Study

by Elena Zappia, Domenico Piccolo, Chiara Del Re, Paolo Bonan, Luca Guarino, Simone Ribero, Hassan Galadari and Steven Paul Nisticò

Photonics 2024, 11(10), 938; https://doi.org/10.3390/photonics11100938 - 6 Oct 2024

Viewed by 1424

Abstract

Background and Objectives: Melasma, a hypermelanotic dermatologic condition that mainly affects women, poses challenges due to its complex etiology involving environmental and genetic factors. Its pathophysiology, marked by intricate histological changes, is not fully understood. This study explored the efficacy and safety [...] Read more.

Background and Objectives: Melasma, a hypermelanotic dermatologic condition that mainly affects women, poses challenges due to its complex etiology involving environmental and genetic factors. Its pathophysiology, marked by intricate histological changes, is not fully understood. This study explored the efficacy and safety of a new 785 nm picosecond laser in treating facial melasma. Materials and Methods: An 11-participant cohort, comprising women with Fitzpatrick phototypes II-III, underwent a treatment protocol with a new 785 nm picosecond laser. The clinical evaluation used the Global Aesthetic International Score (GAIS) and the Five-Point Likert Scale Questionnaire. The aim of the study was to understand the capacity of the 785 nm wavelength laser to interact with both the pigmentary and vascular components of melasma. Results: The GAIS outcomes revealed excellent (18.2%), good (54.5%), poor (18.2%), and no results (9.1%). The Likert Scale responses varied from very satisfied (18.2%) to slightly satisfied (9.1%). Clinical images at three months demonstrated resolution of melasma with no adverse events. Conclusions: This non-invasive procedure showed positive outcomes and high patient tolerance, emphasizing its potential in melasma management. However, in order to fully understand the interactions of pigmentary and vascular components with the 785 nm wavelength laser, further research is required. The small cohort represents a limitation for this study, therefore studies that include a larger number of patients are needed to assess the effectiveness of this laser treatment for facial melasma. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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15 pages, 5942 KiB

Open AccessArticle

Numerical Simulation and Experimental Investigation of Single-Point Picosecond Laser Ablation inside K9 Glass

by Zhanfeng Dai, Yang Xu, Yiying Song, Hongzhi He, Bo Liu, Yong He, Guling Zhang and Xuechun Lin

Photonics 2024, 11(8), 699; https://doi.org/10.3390/photonics11080699 - 27 Jul 2024

Cited by 1 | Viewed by 858

Abstract

K9 glass is a classical transparent material widely used in high-power optical systems due to its high-temperature resistance. However, the precision machining of K9 glass is difficult. The laser processing method, characterized by being non-contact, having a small heat-affected zone, and having high [...] Read more.

K9 glass is a classical transparent material widely used in high-power optical systems due to its high-temperature resistance. However, the precision machining of K9 glass is difficult. The laser processing method, characterized by being non-contact, having a small heat-affected zone, and having high processing precision, is commonly employed for processing intricate structures. In this study, the vector diffraction model is employed to simulate the internal electric field inside the material when focused by objective lenses with varying numerical apertures. Furthermore, the temperature field is simulated. The simulation considered the nonlinear absorption of the material, the stretching of the focal dot due to spherical aberration, and the energy loss of the laser during the focusing process. The experiment indicated that the ablated area consists of numerous small, ablated dots and that multiple ablated areas emerged under an NA of 0.6. This study can provide valuable references for the research of the interaction between lasers and glass materials. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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10 pages, 4271 KiB

Open AccessCommunication

Nonlinear Dynamics of Silicon-Based Epitaxial Quantum Dot Lasers under Optical Injection

by Ruilin Fang, Guang-Qiong Xia, Yan-Fei Zheng, Qing-Qing Wang and Zheng-Mao Wu

Photonics 2024, 11(8), 684; https://doi.org/10.3390/photonics11080684 - 23 Jul 2024

Viewed by 1040

Abstract

For silicon-based epitaxial quantum dot lasers (QDLs), the mismatches of the lattice constants and the thermal expansion coefficients lead to the generation of threaded dislocations (TDs), which act as the non-radiative recombination centers through the Shockley–Read–Hall (SRH) recombination. Based on a three-level model [...] Read more.

For silicon-based epitaxial quantum dot lasers (QDLs), the mismatches of the lattice constants and the thermal expansion coefficients lead to the generation of threaded dislocations (TDs), which act as the non-radiative recombination centers through the Shockley–Read–Hall (SRH) recombination. Based on a three-level model including the SRH recombination, the nonlinear properties of the silicon-based epitaxial QDLs under optical injection have been investigated theoretically. The simulated results show that, through adjusting the injection parameters including injection strength and frequency detuning, the silicon-based epitaxial QDLs can display rich nonlinear dynamical states such as period one (P1), period two (P2), multi-period (MP), chaos (C), and injection locking (IL). Relatively speaking, for a negative frequency detuning, the evolution of the dynamical state with the injection strength is more abundant, and an evolution path P1-P2-MP-C-MP-IL has been observed. Via mapping the dynamical state in the parameter space of injection strength and frequency detuning under different SRH recombination lifetime, the effects of SRH recombination lifetime on the nonlinear dynamical state of silicon-based epitaxial QDLs have been analyzed. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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8 pages, 1448 KiB

Open AccessArticle

Optical Rogue Waves in Fiber Lasers

by Hani J. Kbashi and Sergey V. Sergyev

Photonics 2024, 11(7), 657; https://doi.org/10.3390/photonics11070657 - 12 Jul 2024

Cited by 1 | Viewed by 1318

Abstract

Optical rogue waves are a nonlinear phenomenon that offers a unique opportunity to gain fundamental insights into wave interaction and behavior, and the evolution of complex systems. Optical systems serve as a suitable testbed for the well-controlled investigation of this natural phenomenon, which [...] Read more.

Optical rogue waves are a nonlinear phenomenon that offers a unique opportunity to gain fundamental insights into wave interaction and behavior, and the evolution of complex systems. Optical systems serve as a suitable testbed for the well-controlled investigation of this natural phenomenon, which cannot be easily studied in an ocean environment. Additionally, such systems offer practical applications in telecommunications and optical signal processing, making this topic a vital area of research. Fiber lasers are considered the best candidates for demonstrating and investigating the emergence of optical rogue waves. In particular, they offer significant advantages in nonlinear dynamics due to faster field evolution and a higher number of events that can be recorded within a relatively short time. In this paper, we present the development mechanisms of optical rogue wave events. It was found that multimode vector instability, pulse–pulse interaction, and soliton rain are the main nonlinear dynamics leading to the formation of optical rogue wave events. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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8 pages, 3159 KiB

Open AccessCommunication

High-Power GHz Burst-Mode All-Fiber Laser System with Sub 300 fs Pulse Duration

by Feng Li, Wei Zhao, Yuxi Fu, Jixin Xing, Wenlong Wen, Lei Wang, Qianglong Li, Xue Cao, Hualong Zhao and Yishan Wang

Photonics 2024, 11(6), 570; https://doi.org/10.3390/photonics11060570 - 18 Jun 2024

Cited by 1 | Viewed by 1295

Abstract

An all-fiber low-repetition-rate SESAM mode-locked fiber oscillator combined with a dispersion-managed active fiber loop produces a flexible GHz burst-mode laser source. The high-power output is then produced by amplifying the GHz burst-mode laser source using an all-fiber chirped-pulse amplification system. Then, the laser [...] Read more.

An all-fiber low-repetition-rate SESAM mode-locked fiber oscillator combined with a dispersion-managed active fiber loop produces a flexible GHz burst-mode laser source. The high-power output is then produced by amplifying the GHz burst-mode laser source using an all-fiber chirped-pulse amplification system. Then, the laser is compressed using a grating pair compressor; a maximum amplified power of 97 W is obtained. This results in a compressed high power of 82.07 W with a power stability RMS of 0.09% and beam quality better than 1.2. Accurate dispersion control allows for the production of a high-quality pulse duration of 265 fs. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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11 pages, 3451 KiB

Open AccessArticle

High-Performance Terahertz Coherent Perfect Absorption with Asymmetric Graphene Metasurface

by Jintao Chen, Lujun Hong, Jiangtao Lei, Yun Shen, Xiaohua Deng, Jing Chen and Tianjing Guo

Photonics 2024, 11(6), 544; https://doi.org/10.3390/photonics11060544 - 7 Jun 2024

Cited by 2 | Viewed by 1087

Abstract

In this work, we introduce a novel coherent perfect absorber, accentuating its novelty by emphasizing the broad bandwidth, reduced thickness, tunable property, and straightforward design achieved through the use of an asymmetric graphene metasurface. This design incorporates both square and circular graphene patches [...] Read more.

In this work, we introduce a novel coherent perfect absorber, accentuating its novelty by emphasizing the broad bandwidth, reduced thickness, tunable property, and straightforward design achieved through the use of an asymmetric graphene metasurface. This design incorporates both square and circular graphene patches arranged on either side of a silicon substrate. With an optimized structural design, this absorber consistently captures over 90% of incoming waves across the frequency range of 1.65 to 4.49 THz, with a graphene Fermi level of 0.8 eV, and the whole device measures just 1.5 um thick. This makes our absorber significantly more effective and compact than previous designs. The absorber’s effectiveness can be significantly enhanced by combining the metasurface’s geometric design with the graphene Fermi level. It is anticipated that this ultrathin, wideband coherent perfect absorption device will play a crucial role in emerging on-chip THz communication technologies, including light modulators, photodetectors, and so on. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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10 pages, 2246 KiB

Open AccessArticle

Generation of Bright–Dark Pulse Pairs in the Er-Doped Mode-Locked Fiber Laser Based on Doped Fiber Saturable Absorber

by Yaoyao Qi, Qixing Yu, Wei Sun, Yaqing Gao, Yu Zhang, Zhenxu Bai, Jie Ding, Bingzheng Yan, Yulei Wang, Zhiwei Lu and Dapeng Yan

Photonics 2024, 11(6), 534; https://doi.org/10.3390/photonics11060534 - 3 Jun 2024

Cited by 4 | Viewed by 907

Abstract

This study reports new types of passive mode-locked Er-doped fiber laser (EDFL) based on a segment of doped fiber saturable absorber (DFSA) with Tm/Ho-doped fiber (THDF), Yb-doped fiber (YDF), and Er-doped fiber (EDF). By employing THDF-SA, a bright pulse sequence with a fundamental [...] Read more.

This study reports new types of passive mode-locked Er-doped fiber laser (EDFL) based on a segment of doped fiber saturable absorber (DFSA) with Tm/Ho-doped fiber (THDF), Yb-doped fiber (YDF), and Er-doped fiber (EDF). By employing THDF-SA, a bright pulse sequence with a fundamental repetition rate of 17.86 MHz was obtained. In addition, various mode-locked output states, including dark pulses, dark–bright pulse pairs, bright–dark pulse pairs, and second-harmonic pulses, were obtained through polarization modulation and gain modulation, and the orthogonality of dark–bright pulses in both polarization directions was verified. Furthermore, using EDF-SA and YDF-SA, dark pulses and dark–bright pulses were obtained. A comparison of the three experiments revealed that THDF-SA effectively reduces the mode-locked threshold and improves the average output power. Compared with bright pulses, dark pulses offer several advantages such as resisting noise, increasing propagation speed, and suppressing nonlinear scattering (such as pulse-intrinsic Raman scattering); thus, the EDFL can find broad application in long-distance transmission, precision measurement, and other fields. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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14 pages, 3394 KiB

Open AccessArticle

High-Performance Fiber Ring Laser Based on Polarization Space Parity-Time Symmetry Breaking

by Fengling Zhang, Zhengmao Wu, Xin Tong and Guangqiong Xia

Photonics 2024, 11(6), 501; https://doi.org/10.3390/photonics11060501 - 25 May 2024

Viewed by 1563

Abstract

This work proposes and experimentally demonstrates a high-performance polarization space parity-time (PT) symmetric fiber ring laser to achieve a low-noise, narrow-linewidth, and highly stable single-longitudinal-mode output. The gain/loss and coupling coefficients are regulated by adjusting a polarization controller (PC) and the pumping current [...] Read more.

This work proposes and experimentally demonstrates a high-performance polarization space parity-time (PT) symmetric fiber ring laser to achieve a low-noise, narrow-linewidth, and highly stable single-longitudinal-mode output. The gain/loss and coupling coefficients are regulated by adjusting a polarization controller (PC) and the pumping current of an erbium-doped fiber amplifier (EDFA) within the ring cavity. The results show that the single longitudinal mode oscillation of the laser can be implemented by PT symmetry breaking. The frequency noise spectral density and the linewidth characteristics of the laser are evaluated by the short-delay self-heterodyne method. The results reveal that excellent low-frequency noise (181 Hz²/Hz at a 10 kHz offset frequency) and narrow fundamental linewidth (68 Hz) can be achieved. Additionally, the laser exhibits outstanding stability with only 0.64 pm wavelength drift over 30 min. By tuning an optical tunable filter (OTF), the wavelength tunable range of the laser can cover the entire C-band. Furthermore, the impacts of different fiber length on the frequency noise spectral density and the filter bandwidth on stability are analyzed, offering guidance for component selection in such laser systems. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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13 pages, 4516 KiB

Open AccessArticle

Broadband High-Linear FMCW Light Source Based on Spectral Stitching

by Liang Sun, Xinguang Zhou, Haohao Zhao, Shichang Xu, Zihan Wu, Guohui Yuan and Zhuoran Wang

Photonics 2024, 11(5), 477; https://doi.org/10.3390/photonics11050477 - 19 May 2024

Viewed by 1241

Abstract

The key to realizing a high-performance frequency-modulated continuous wave (FMCW) laser frequency-sweeping light source is how to extend the frequency-swept bandwidth and eliminate the effect of nonlinearity. To solve these issues, this paper designs a broadband high-linear FMCW frequency-sweeping light source system based [...] Read more.

The key to realizing a high-performance frequency-modulated continuous wave (FMCW) laser frequency-sweeping light source is how to extend the frequency-swept bandwidth and eliminate the effect of nonlinearity. To solve these issues, this paper designs a broadband high-linear FMCW frequency-sweeping light source system based on the combination of fixed temperature control and digital optoelectronic phase-locked loop (PLL), which controls the temperatures of the two lasers separately and attempts to achieve the coarse spectral stitching based on a time-division multiplexing scheme. Furthermore, we uses the PLL to correct the frequency error more specifically after the coarse stitching, which achieves the spectrum fine stitching and, meanwhile, realizes the nonlinearity correction. The experimental results show that our scheme can successfully achieve bandwidth expansion and nonlinearity correction, and the sweeping bandwidth is twice as much as that of the original single laser. The full-width half-maximum (FWHM) of the FMCW output is reduced from 150 kHz to 6.1 kHz, which exhibits excellent nonlinear correction performance. The relative error of the FMCW ranging system based on this frequency-swept light source is also reduced from 1.628% to 0.673%. Therefore, our frequency-swept light source with excellent performance has a promising application in the FMCW laser ranging system. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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11 pages, 4572 KiB

Open AccessArticle

Characterizing Extreme Events in a Fabry–Perot Laser with Optical Feedback

by Shanshan Ge, Yu Huang, Kun Li, Pei Zhou, Penghua Mu, Xin Zhu and Nianqiang Li

Photonics 2024, 11(5), 462; https://doi.org/10.3390/photonics11050462 - 15 May 2024

Viewed by 1164

Abstract

The study of extreme events (EEs) in photonics has expanded significantly due to straightforward implementation conditions. EEs have not been discussed systematically, to the best of our knowledge, in the chaotic dynamics of a Fabry–Perot laser with optical feedback, so we address this [...] Read more.

The study of extreme events (EEs) in photonics has expanded significantly due to straightforward implementation conditions. EEs have not been discussed systematically, to the best of our knowledge, in the chaotic dynamics of a Fabry–Perot laser with optical feedback, so we address this in the current contribution. Herein, we not only find EEs in all modes but also divide the EEs in total output into two categories for further discussion. The two types of EEs have similar statistical features to conventional rogue waves. The occurrence probability of EEs undergoes a saturation effect as the feedback strength increases. Additionally, we analyze the influence of feedback strength, feedback delay, and pump current on the probability of EEs defined by two criteria of EEs and find similar trends. We hope that this work contributes to a deep understanding and serves as inspiration for further research into various multimode semiconductor laser systems. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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Review

Jump to: Research

20 pages, 6113 KiB

Open AccessReview

Continuous-Wave Self-Raman Vanadate Lasers Generating Versatile Visible Wavelengths

by Di Li, Chien-Yen Huang, Xiu-Wei Chang, Hsing-Chih Liang and Yung-Fu Chen

Photonics 2024, 11(7), 601; https://doi.org/10.3390/photonics11070601 - 26 Jun 2024

Cited by 1 | Viewed by 1405

Abstract

In this review, the developments of efficient high-power CW orange-lime-green lasers by using intracavity stimulated Raman Scattering (SRS) in Nd-doped vanadate lasers are systematically discussed. The overall properties of the spontaneous Raman spectra in Nd:YVO₄ and Nd:GdVO₄ crystals are overviewed. The [...] Read more.

In this review, the developments of efficient high-power CW orange-lime-green lasers by using intracavity stimulated Raman Scattering (SRS) in Nd-doped vanadate lasers are systematically discussed. The overall properties of the spontaneous Raman spectra in Nd:YVO₄ and Nd:GdVO₄ crystals are overviewed. The critical phase matchings of using the lithium triborate (LBO) crystals for sum frequency generation (SFG) and second harmonic generation (SHG) are thoroughly reviewed. We make a detailed review for achieving the individual green-lime-orange emissions from the self-Raman Nd:YVO₄ and Nd:GdVO₄ lasers with LBO crystals. The following is to review the dual-wavelength operations of the lime-green and orange-green lasers. Finally, the procedure for generating the triple-wavelength operation of orange-lime-green simultaneous emissions is completely described. The present review is expected to be useful for developing compact, efficient, high-power CW visible lasers for applications including medical treatment, biology, spectroscopy, and remote sensing. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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