Pub Date : 2024-10-29DOI: 10.1016/j.optlastec.2024.112022
Piotr Jaworski, Piotr Bojęś, Karol Krzempek
In this article we explore the possibility of utilizing 1560 nm nanosecond dissipative soliton resonance pulses for generation of supercontinuum radiation in a standard singlemode fiber. The source is based on a non-complex, all-in-fiber dissipative soliton resonance mode-locked laser and two sections of fiber amplifiers, boosting the peak power and pulse energy to 147 W and 0.42 µJ, respectively. Pulses with a repetition rate and pulse duration of ∼1.01048 MHz and 2.67 ns, respectively, were injected into a standard singlemode fiber (SMF-28, Corning) with lengths between 100 m and 600 m. Induced Stimulated Raman Scattering effect resulted in a broadening of the pulse spectrum from the initial 1560 nm, up to ∼2100 nm. Our results are the first demonstration of using high-energy nanosecond pulses from a non-complex, all-in-fiber dissipative soliton resonance mode-locked laser in a frequency conversion process in a standard singlemode fiber. The proposed approach delivers an alternative solution to broadband light generation using complex nanosecond laser sources.
本文探讨了利用 1560 nm 纳秒耗散孤子共振脉冲在标准单模光纤中产生超连续辐射的可能性。该光源基于非复杂的全光纤耗散孤子共振锁模激光器和两段光纤放大器，可将峰值功率和脉冲能量分别提高到 147 W 和 0.42 µJ。将重复率和脉冲持续时间分别为 1.01048 MHz 和 2.67 ns 的脉冲注入长度介于 100 m 和 600 m 之间的标准单模光纤（SMF-28，康宁公司）。诱导受激拉曼散射效应使脉冲光谱从最初的 1560 nm 扩展到 2100 nm。我们的研究结果首次证明，在标准单模光纤的频率转换过程中，可以使用来自非复合全光纤耗散孤子共振模式锁定激光器的高能纳秒脉冲。所提出的方法为使用复杂纳秒激光源产生宽带光提供了另一种解决方案。
{"title":"Supercontinuum generation in singlemode fibers using dissipative soliton resonance pulses at 1560 nm","authors":"Piotr Jaworski, Piotr Bojęś, Karol Krzempek","doi":"10.1016/j.optlastec.2024.112022","DOIUrl":"10.1016/j.optlastec.2024.112022","url":null,"abstract":"<div><div>In this article we explore the possibility of utilizing 1560 nm nanosecond dissipative soliton resonance pulses for generation of supercontinuum radiation in a standard singlemode fiber. The source is based on a non-complex, all-in-fiber dissipative soliton resonance mode-locked laser and two sections of fiber amplifiers, boosting the peak power and pulse energy to 147 W and 0.42 µJ, respectively. Pulses with a repetition rate and pulse duration of ∼1.01048 MHz and 2.67 ns, respectively, were injected into a standard singlemode fiber (SMF-28, Corning) with lengths between 100 m and 600 m. Induced Stimulated Raman Scattering effect resulted in a broadening of the pulse spectrum from the initial 1560 nm, up to ∼2100 nm. Our results are the first demonstration of using high-energy nanosecond pulses from a non-complex, all-in-fiber dissipative soliton resonance mode-locked laser in a frequency conversion process in a standard singlemode fiber. The proposed approach delivers an alternative solution to broadband light generation using complex nanosecond laser sources.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 112022"},"PeriodicalIF":4.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.optlastec.2024.112034
Hai-Jie Zhang , Shun Gu , Hui Long , Min-Ru Wen , Hua-Feng Dong , Li-Li Tao , Xin Zhang , Fu-Gen Wu , Li Chen
Nb2SiTe4 (NST) has been shown air-stable with narrow band gap, high electron mobility, excellent absorption properties, and anisotropic optical properties. In this research, liquid phase exfoliation method was employed to prepare NST QDs which were subsequently applied to the tapered fiber to form saturable absorbers for erbium-doped fiber laser. A two-armed balanced probing system was used to assess the nonlinear optical properties, resulting a saturation intensity of 2.36 KW/cm2 and a modulation depth of 9.56%. Following the implementation of the NST QDs-SA to Er-doped fiber laser (EDFL) system, stable mode-locked pulses were produced exhibiting the center wavelength of 1574.43 nm, the repetition frequency of 21.50 MHz, and the pulse duration of 747 fs. Those results demonstrate the potential of NST as a narrowband SA, offering new avenues for the design of air-stable ultrafast photonic devices.
{"title":"Mode-locked erbium-doped fiber laser based on stable narrow-gap semiconductor Nb2SiTe4 quantum dots","authors":"Hai-Jie Zhang , Shun Gu , Hui Long , Min-Ru Wen , Hua-Feng Dong , Li-Li Tao , Xin Zhang , Fu-Gen Wu , Li Chen","doi":"10.1016/j.optlastec.2024.112034","DOIUrl":"10.1016/j.optlastec.2024.112034","url":null,"abstract":"<div><div>Nb<sub>2</sub>SiTe<sub>4</sub> (NST) has been shown air-stable with narrow band gap, high electron mobility, excellent absorption properties, and anisotropic optical properties. In this research, liquid phase exfoliation method was employed to prepare NST QDs which were subsequently applied to the tapered fiber to form saturable absorbers for erbium-doped fiber laser. A two-armed balanced probing system was used to assess the nonlinear optical properties, resulting a saturation intensity of 2.36 KW/cm<sup>2</sup> and a modulation depth of 9.56%. Following the implementation of the NST QDs-SA to Er-doped fiber laser (EDFL) system, stable mode-locked pulses were produced exhibiting the center wavelength of 1574.43 nm, the repetition frequency of 21.50 MHz, and the pulse duration of 747 fs. Those results demonstrate the potential of NST as a narrowband SA, offering new avenues for the design of air-stable ultrafast photonic devices.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 112034"},"PeriodicalIF":4.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.optlastec.2024.111985
Junqi Yao , Yaxin Yu , Jiao Zhang , Min Zhu , Jinbiao Xiao
Silicon photonic polarization beam splitter (PBS) is a crucial component for on-chip polarization management. PBSs typically function based on wavelength-dependent mechanisms such as evanescent coupling and modal interference. As a result, constructing a PBS with a broad bandwidth, low insertion loss, and high extinction ratio remains a significant challenge. This paper presents a novel method for achieving a PBS that is almost independent of the wavelength, which involves engineering the modal birefringence of subwavelength grating waveguides and utilizing reciprocal mode transitions. An input taper is embedded in polarization-selective metamaterials (PSMs), which are made up of two sets of subwavelength gratings arranged in different directions. As the width of the input taper decreases, the waveguide mode is no longer supported and transits into a single-mode-like (SML) component guided in the SWG waveguide. By exploiting the principle that a mode will preferentially evolve into the mode with the closest effective refractive index, polarization beam splitting is achieved during the transition of waveguide modes into SML components guided in SWGs with different arrangement directions. Results show that the proposed PBS achieves a high extinction ratio of more than 23 dB throughout a bandwidth of 600 nm (1.2–1.8 μm) for both polarizations. For TE/TM polarization, the bandwidth to achieve an insertion loss of lower than 0.41/1 dB is as large as 600 nm (1.2–1.8 μm)/530 nm (1.23–1.76 μm). As far as we know, this is the PBS with the most superior broadband performance proposed till now.
{"title":"Silicon photonic polarization beam splitter assisted by polarization-Selective metamaterials with 600 nm bandwidth","authors":"Junqi Yao , Yaxin Yu , Jiao Zhang , Min Zhu , Jinbiao Xiao","doi":"10.1016/j.optlastec.2024.111985","DOIUrl":"10.1016/j.optlastec.2024.111985","url":null,"abstract":"<div><div>Silicon photonic polarization beam splitter (PBS) is a crucial component for on-chip polarization management. PBSs typically function based on wavelength-dependent mechanisms such as evanescent coupling and modal interference. As a result, constructing a PBS with a broad bandwidth, low insertion loss, and high extinction ratio remains a significant challenge. This paper presents a novel method for achieving a PBS that is almost independent of the wavelength, which involves engineering the modal birefringence of subwavelength grating waveguides and utilizing reciprocal mode transitions. An input taper is embedded in polarization-selective metamaterials (PSMs), which are made up of two sets of subwavelength gratings arranged in different directions. As the width of the input taper decreases, the waveguide mode is no longer supported and transits into a single-mode-like (SML) component guided in the SWG waveguide. By exploiting the principle that a mode will preferentially evolve into the mode with the closest effective refractive index, polarization beam splitting is achieved during the transition of waveguide modes into SML components guided in SWGs with different arrangement directions. Results show that the proposed PBS achieves a high extinction ratio of more than 23 dB throughout a bandwidth of 600 nm (1.2–1.8 μm) for both polarizations. For TE/TM polarization, the bandwidth to achieve an insertion loss of lower than 0.41/1 dB is as large as 600 nm (1.2–1.8 μm)/530 nm (1.23–1.76 μm). As far as we know, this is the PBS with the most superior broadband performance proposed till now.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111985"},"PeriodicalIF":4.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.optlastec.2024.112026
Yifang Chen , Quanjiang Lv , Ju Liu , Xu Huang , Yiwei Cao , Tianpeng Yang , Tingting Mi , Xiaowen Wang , Junlin Liu
Current crowding and poor reliability due to uneven current distribution are significant challenges limiting the widespread application of AlGaN-based flip-chip deep-ultraviolet (DUV) LEDs. Herein, a novel triangular island-shaped chip structure designed to mitigate current crowding and enhance device reliability. Although this structure exhibits increased leakage current due to etching damage and the reduced effective light-emitting area compared to the interdigitated structure, it demonstrates lower operating voltage and higher wall-plug efficiency at high currents. Optical emission distribution tests confirm that the triangular island-shaped structure effectively reduces current crowding and achieves uniform light emission. After 500 h of aging, the optical power retention of the triangular island-shaped structure remains at 97.6%, and the L70 lifetime, as predicted by a lifetime model, is extended by 45% compared to the interdigitated structure. These findings highlight the critical role of mitigating current crowding in improving the reliability of AlGaN-based DUV LED chip structures.
电流拥挤和电流分布不均导致的可靠性差是限制基于氮化铝的倒装芯片深紫外（DUV）发光二极管广泛应用的重大挑战。本文介绍了一种新颖的三角形岛状芯片结构，旨在缓解电流拥挤并提高器件可靠性。虽然这种结构会因蚀刻损伤和有效发光面积减小而导致漏电流增加，但与相互咬合的结构相比，它在大电流条件下的工作电压更低，壁插效率更高。光学发射分布测试证实，三角形岛状结构能有效减少电流拥挤，实现均匀发光。老化 500 小时后，三角岛形结构的光功率保持率仍为 97.6%，根据寿命模型预测的 L70 寿命比插接结构延长了 45%。这些发现凸显了减轻电流拥挤对提高基于氮化铝的 DUV LED 芯片结构可靠性的关键作用。
{"title":"Mitigating current crowding for enhanced reliability of AlGaN-based deep-ultraviolet LEDs through triangular island-shaped p-electrode design","authors":"Yifang Chen , Quanjiang Lv , Ju Liu , Xu Huang , Yiwei Cao , Tianpeng Yang , Tingting Mi , Xiaowen Wang , Junlin Liu","doi":"10.1016/j.optlastec.2024.112026","DOIUrl":"10.1016/j.optlastec.2024.112026","url":null,"abstract":"<div><div>Current crowding and poor reliability due to uneven current distribution are significant challenges limiting the widespread application of AlGaN-based flip-chip deep-ultraviolet (DUV) LEDs. Herein, a novel triangular island-shaped chip structure designed to mitigate current crowding and enhance device reliability. Although this structure exhibits increased leakage current due to etching damage and the reduced effective light-emitting area compared to the interdigitated structure, it demonstrates lower operating voltage and higher wall-plug efficiency at high currents. Optical emission distribution tests confirm that the triangular island-shaped structure effectively reduces current crowding and achieves uniform light emission. After 500 h of aging, the optical power retention of the triangular island-shaped structure remains at 97.6%, and the L70 lifetime, as predicted by a lifetime model, is extended by 45% compared to the interdigitated structure. These findings highlight the critical role of mitigating current crowding in improving the reliability of AlGaN-based DUV LED chip structures.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 112026"},"PeriodicalIF":4.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The authors demonstrated the cutting of ultra-thin glass (UTG) with a thickness of 100 μm using a laser fusion cutting approach, which showed significant potential for drastically improving flexural strength. The authors proposed a novel control method for optimizing the edge shape to avoid previously reported drooping. Additionally, the authors presented guidelines for reducing the residual stress on the glass edge using two laser-superposed spots, resulting in a reduction in the retardation value by ∼ 43 %. The two-point bending test indicated that the maximum strength exceeded 500 MPa, whereas the minimum strength was approximately 100 MPa, which was likely caused by spatter deposition.
{"title":"Reaching over 500 MPa maximum flexural strength in ultra-thin glass via CO2 laser fusion cutting","authors":"Sho Itoh , Naoto Nagano , Yusuke Kubota , Kohei Matsumoto , Masataka Sato , Souta Matsusaka , Hirofumi Hidai","doi":"10.1016/j.optlastec.2024.112004","DOIUrl":"10.1016/j.optlastec.2024.112004","url":null,"abstract":"<div><div>The authors demonstrated the cutting of ultra-thin glass (UTG) with a thickness of 100 μm using a laser fusion cutting approach, which showed significant potential for drastically improving flexural strength. The authors proposed a novel control method for optimizing the edge shape to avoid previously reported drooping. Additionally, the authors presented guidelines for reducing the residual stress on the glass edge using two laser-superposed spots, resulting in a reduction in the retardation value by ∼ 43 %. The two-point bending test indicated that the maximum strength exceeded 500 MPa, whereas the minimum strength was approximately 100 MPa, which was likely caused by spatter deposition.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 112004"},"PeriodicalIF":4.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.optlastec.2024.112009
Dianzheng Wang, Kailun Li, Jun Yao, Baorui Du, Yuchen Xu
Previously, the additive manufacturing of pure copper was carried out using a large-spot (0.2 mm) infrared or green laser. In this study, the laser powder bed fusion (LPBF) of pure copper using a green laser with a 532 nm wavelength and a fine spot (40 μm) was investigated. After the optimization of the process parameters, pure copper blocks with a maximum density of 99.6 % were prepared. Using micro-CT, three porosity defects that affect the densification and tensile properties of pure copper were identified, namely lack-of-fusion, keyhole, and small-hole porosities. An obvious < 110 > texture in the build direction was observed in the fabricated pure copper blocks. Anisotropy of the mechanical properties was found and can be attributed to the interaction between the textures and porosities during the tensile process.
{"title":"Porosity, texture, and mechanical properties of pure copper fabricated by fine green laser powder bed fusion","authors":"Dianzheng Wang, Kailun Li, Jun Yao, Baorui Du, Yuchen Xu","doi":"10.1016/j.optlastec.2024.112009","DOIUrl":"10.1016/j.optlastec.2024.112009","url":null,"abstract":"<div><div>Previously, the additive manufacturing of pure copper was carried out using a large-spot (0.2 mm) infrared or green laser. In this study, the laser powder bed fusion (LPBF) of pure copper using a green laser with a 532 nm wavelength and a fine spot (40 μm) was investigated. After the optimization of the process parameters, pure copper blocks with a maximum density of 99.6 % were prepared. Using micro-CT, three porosity defects that affect the densification and tensile properties of pure copper were identified, namely lack-of-fusion, keyhole, and small-hole porosities. An obvious < 110 > texture in the build direction was observed in the fabricated pure copper blocks. Anisotropy of the mechanical properties was found and can be attributed to the interaction between the textures and porosities during the tensile process.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 112009"},"PeriodicalIF":4.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-29DOI: 10.1016/j.optlastec.2024.112040
Junyun Chen , Shilong Chen , Zihao Lin , Tianye Jin , Anmin Nie
The diamond micro-milling tool is a crucial component in micro-milling technology, indispensable for the precise machining of miniaturized parts and structures. However, the manufacturing efficiency of diamond micro-milling tools is challenging due to its extreme mechanical property and micro-sized feature. In this study, Water-Jet Guided laser (WJGL) technology was explored to prepare single-crystal diamond micro-milling tool, aiming to achieve industrial-grade processing efficiency. Both energy-related parameters (laser power and scanning speed) and fluid-related parameters (water flow and shield gas) were investigated to identify the optimal conditions for superior machining quality and material removal rate (MRR). Through cutting through experiments, it was observed that medium laser energy density was most effective in enhancing surface morphology, while high energy led to excessive ablation and low energy resulted in insufficient material removal ability. Moreover, water flow and shield gas affected the kinetic energy of water jet, which reacted on the water stability and subsequent machining quality. MRR was measured and calculated via surface grooving experiments, with ablation ability being the dominant factor. The optimal parameter combination was P = 16 W, v = 6 mm/s, water pressure = 300 bar, and gas flow rate = 1.5 NL/min, achieving the surface roughness Sa/Sz = 149.9 nm/1.503 μ m and MRR of 22.976 × 10-3 mm3/s. A single-crystal diamond micro-milling tool was finally well-prepared within 2 min, with higher machining precision and efficiency compared to conventional methods, highlighting the potential of WJGL for mass production of high-quality diamond micro-milling tools.
{"title":"Enhancing machining efficiency and precision: Water-jet guided laser fabrication of diamond micro-milling tool","authors":"Junyun Chen , Shilong Chen , Zihao Lin , Tianye Jin , Anmin Nie","doi":"10.1016/j.optlastec.2024.112040","DOIUrl":"10.1016/j.optlastec.2024.112040","url":null,"abstract":"<div><div>The diamond micro-milling tool is a crucial component in micro-milling technology, indispensable for the precise machining of miniaturized parts and structures. However, the manufacturing efficiency of diamond micro-milling tools is challenging due to its extreme mechanical property and micro-sized feature. In this study, Water-Jet Guided laser (WJGL) technology was explored to prepare single-crystal diamond micro-milling tool, aiming to achieve industrial-grade processing efficiency. Both energy-related parameters (laser power and scanning speed) and fluid-related parameters (water flow and shield gas) were investigated to identify the optimal conditions for superior machining quality and material removal rate (MRR). Through cutting through experiments, it was observed that medium laser energy density was most effective in enhancing surface morphology, while high energy led to excessive ablation and low energy resulted in insufficient material removal ability. Moreover, water flow and shield gas affected the kinetic energy of water jet, which reacted on the water stability and subsequent machining quality. MRR was measured and calculated via surface grooving experiments, with ablation ability being the dominant factor. The optimal parameter combination was <em>P</em> = 16 W, <em>v</em> = 6 mm/s, water pressure = 300 bar, and gas flow rate = 1.5 NL/min, achieving the surface roughness Sa/Sz = 149.9 nm/1.503 μ m and MRR of 22.976 × 10<sup>-3</sup> mm<sup>3</sup>/s. A single-crystal diamond micro-milling tool was finally well-prepared within 2 min, with higher machining precision and efficiency compared to conventional methods, highlighting the potential of WJGL for mass production of high-quality diamond micro-milling tools.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 112040"},"PeriodicalIF":4.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, an infrared femtosecond laser was used to polish silicon carbide ceramics at large incidence angles. For silicon carbide ceramics with different initial roughness surfaces, the improvement mechanism of laser incident angle on polishing surface quality was systematically analyzed. The effects of other process factors during laser polishing, including spot overlap rate, laser power, and scanning times, on the polishing quality when processing with a large incident angle was investigated. The results indicate that, compared to a vertically incident laser, laser polishing at large incident angles significantly enhances surface roughness. During the polishing process, the laser first removes the higher convex structures on the surface, which helps level peaks to obtain a smooth material surface. Additionally, at an incident angle of 80°, the surface roughness of the polished surface gradually decreases with the increase of the spot overlap rate in the X direction and the Y direction. The roughness only increases when the X-direction overlap rate is 95 %. As single pulse energy increases, the roughness of the polished surface shows a trend of initially increasing and then decreasing. With the increase in laser repetition frequency, the roughness of the polished surface shows a general trend of slow decrease. As the scanning times increase, the roughness of the polished surface generally exhibits a trend of initially decreasing and then increasing. Throughout the experimental process, when the laser incidence angle was set at 80°, the pulse energy at 85 μJ, the overlap rate in the X direction at 90 %, the overlap rate in the Y direction at 95 %, the laser repetition rate at 35 kHz, and the scanning times at 6, the surface roughness of the silicon carbide ceramic reached a minimum of 0.74 μm with the 1000 × magnification.
本文采用红外飞秒激光对碳化硅陶瓷进行大入射角抛光。针对不同初始粗糙度表面的碳化硅陶瓷，系统分析了激光入射角对抛光表面质量的改善机理。研究了激光抛光过程中的其他工艺因素（包括光斑重叠率、激光功率和扫描时间）对大入射角加工时抛光质量的影响。结果表明，与垂直入射激光相比，大入射角激光抛光能显著提高表面粗糙度。在抛光过程中，激光首先会去除表面较高的凸起结构，这有助于平整峰值，从而获得光滑的材料表面。此外，在入射角为 80° 时，抛光表面的粗糙度会随着 X 方向和 Y 方向光斑重叠率的增加而逐渐降低。只有当 X 方向重叠率为 95% 时，粗糙度才会增加。随着单脉冲能量的增加，抛光表面的粗糙度呈现先增加后减小的趋势。随着激光重复频率的增加，抛光表面的粗糙度总体上呈缓慢下降趋势。随着扫描时间的增加，抛光表面的粗糙度总体上呈现出先减小后增大的趋势。在整个实验过程中，当激光入射角设定为 80°，脉冲能量为 85 μJ，X 方向重叠率为 90%，Y 方向重叠率为 95%，激光重复频率为 35 kHz，扫描次数为 6 次时，碳化硅陶瓷的表面粗糙度在 1000 × 放大倍率下达到最小值 0.74 μm。
{"title":"Experimental study on the multiscale surface morphology of femtosecond laser polishing of silicon carbide ceramics based on inclination angle effect","authors":"Jianbo Chen , Xiaoxiao Chen , Xuanhua Zhang , Yuhang Zhou , Chengnuo Yi , Wenwu Zhang","doi":"10.1016/j.optlastec.2024.111978","DOIUrl":"10.1016/j.optlastec.2024.111978","url":null,"abstract":"<div><div>In this paper, an infrared femtosecond laser was used to polish silicon carbide ceramics at large incidence angles. For silicon carbide ceramics with different initial roughness surfaces, the improvement mechanism of laser incident angle on polishing surface quality was systematically analyzed. The effects of other process factors during laser polishing, including spot overlap rate, laser power, and scanning times, on the polishing quality when processing with a large incident angle was investigated. The results indicate that, compared to a vertically incident laser, laser polishing at large incident angles significantly enhances surface roughness. During the polishing process, the laser first removes the higher convex structures on the surface, which helps level peaks to obtain a smooth material surface. Additionally, at an incident angle of 80°, the surface roughness of the polished surface gradually decreases with the increase of the spot overlap rate in the X direction and the Y direction. The roughness only increases when the X-direction overlap rate is 95 %. As single pulse energy increases, the roughness of the polished surface shows a trend of initially increasing and then decreasing. With the increase in laser repetition frequency, the roughness of the polished surface shows a general trend of slow decrease. As the scanning times increase, the roughness of the polished surface generally exhibits a trend of initially decreasing and then increasing. Throughout the experimental process, when the laser incidence angle was set at 80°, the pulse energy at 85 μJ, the overlap rate in the X direction at 90 %, the overlap rate in the Y direction at 95 %, the laser repetition rate at 35 kHz, and the scanning times at 6, the surface roughness of the silicon carbide ceramic reached a minimum of 0.74 μm with the 1000 × magnification.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 111978"},"PeriodicalIF":4.6,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.optlastec.2024.112014
Yuanhang Zeng, Guangzhi Zhu, Xiao Zhu
The propagation of ultrashort pulses in optical fibers exhibits highly complex nonlinear dynamics, which plays a central role in the development of light sources and photonic technologies. The mainstream of the existing methods for modeling and predicting complex nonlinear propagation dynamics of ultrashort pulses in optical fibers is based on recurrent neural networks (RNNs), which use a Multi-In-Single-Out (MISO) architecture to predict the optical pulse evolution recursively. This autoregressive model is severely limited by the error accumulation problem and also requires significant computational resources. Affected by the error accumulation problem, this method often leads to severe performance degradation in long sequence prediction tasks, thus limiting the practical application of the prediction model. In this work, we propose a new non-autoregressive model using a Single-In-Multi-Out (SIMO) architecture to simulate the highly nonlinear dynamics of ultrashort pulse propagation in optical fibers. Our model is validated on the public dataset. The results show that our model can significantly reduce the prediction error in modeling and predicting the complex nonlinear propagation of ultrashort pulses in optical fibers. In addition, the required computational resources and time spent are significantly reduced. As a whole, our proposed method comprehensively outperforms the mainstream methods in terms of efficiency, accuracy and practicality. We believe our work could bring new insights into the modeling and analysis of complex ultrafast nonlinear dynamics.
{"title":"Seq2Seq model with attention for predicting nonlinear propagation of ultrafast pulses in optical fibers","authors":"Yuanhang Zeng, Guangzhi Zhu, Xiao Zhu","doi":"10.1016/j.optlastec.2024.112014","DOIUrl":"10.1016/j.optlastec.2024.112014","url":null,"abstract":"<div><div>The propagation of ultrashort pulses in optical fibers exhibits highly complex nonlinear dynamics, which plays a central role in the development of light sources and photonic technologies. The mainstream of the existing methods for modeling and predicting complex nonlinear propagation dynamics of ultrashort pulses in optical fibers is based on recurrent neural networks (RNNs), which use a Multi-In-Single-Out (MISO) architecture to predict the optical pulse evolution recursively. This autoregressive model is severely limited by the error accumulation problem and also requires significant computational resources. Affected by the error accumulation problem, this method often leads to severe performance degradation in long sequence prediction tasks, thus limiting the practical application of the prediction model. In this work, we propose a new non-autoregressive model using a Single-In-Multi-Out (SIMO) architecture to simulate the highly nonlinear dynamics of ultrashort pulse propagation in optical fibers. Our model is validated on the public dataset. The results show that our model can significantly reduce the prediction error in modeling and predicting the complex nonlinear propagation of ultrashort pulses in optical fibers. In addition, the required computational resources and time spent are significantly reduced. As a whole, our proposed method comprehensively outperforms the mainstream methods in terms of efficiency, accuracy and practicality. We believe our work could bring new insights into the modeling and analysis of complex ultrafast nonlinear dynamics.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 112014"},"PeriodicalIF":4.6,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.optlastec.2024.112021
Zehui Gu, Yuyang He, Jinghu Ji, Yonghong Fu
The laser beam tilt induces significant changes in the shape of irradiation on the material surface, thereby affecting the ablation contour. However, the influence of tilted laser beams on micro-hole machining remains confined to a simplistic approach. This paper combines experimental and finite element simulation studies to investigate the impact of the laser angle of the incident (AOI) on micro-hole machining with picosecond lasers. A two-dimensional finite element model, including the two-temperature equation and the deformable geometry module, is established to simulate the ablative process of tilted picosecond laser beams on stainless steel. Single-pulse and multiple-pulse ablations under different AOIs are simulated using the model. Experimental results demonstrate that the inclination angle of micro-holes linearly decreases with increasing AOI, resulting in smoother hole wall surfaces. Simulation results reveal a logarithmic decrease in the peak temperatures of electrons and lattice with AOI, which is attributed to the increase in irradiation area and its influence on peak intensity. Under multiple-pulse irradiation, the ablation contour gradually tilts as AOI increases, and the ablation depth follows a logarithmic decrease with AOI.
{"title":"Numerical simulation and experimental study of the shape variation influence on stainless steel drilling with picosecond laser","authors":"Zehui Gu, Yuyang He, Jinghu Ji, Yonghong Fu","doi":"10.1016/j.optlastec.2024.112021","DOIUrl":"10.1016/j.optlastec.2024.112021","url":null,"abstract":"<div><div>The laser beam tilt induces significant changes in the shape of irradiation on the material surface, thereby affecting the ablation contour. However, the influence of tilted laser beams on micro-hole machining remains confined to a simplistic approach. This paper combines experimental and finite element simulation studies to investigate the impact of the laser angle of the incident (AOI) on micro-hole machining with picosecond lasers. A two-dimensional finite element model, including the two-temperature equation and the deformable geometry module, is established to simulate the ablative process of tilted picosecond laser beams on stainless steel. Single-pulse and multiple-pulse ablations under different AOIs are simulated using the model. Experimental results demonstrate that the inclination angle of micro-holes linearly decreases with increasing AOI, resulting in smoother hole wall surfaces. Simulation results reveal a logarithmic decrease in the peak temperatures of electrons and lattice with AOI, which is attributed to the increase in irradiation area and its influence on peak intensity. Under multiple-pulse irradiation, the ablation contour gradually tilts as AOI increases, and the ablation depth follows a logarithmic decrease with AOI.</div></div>","PeriodicalId":19511,"journal":{"name":"Optics and Laser Technology","volume":"181 ","pages":"Article 112021"},"PeriodicalIF":4.6,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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