1 南开大学电子信息与光学工程学院微尺度光学信息技术科学重点实验室,天津 300350
2 山东大学晶体材料国家重点实验室,山东 济南 250100
Overview: With the development of modern manufacturing, the size of optical devices is gradually developing towards miniaturization, and integrated optics is also developing to become a topical area of research for many scholars. One of the methods used for producing micro/nano optical devices is femtosecond laser direct writing, a fine three-dimensional processing technique that has been extensively studied by many scholars for its applicability to most materials and can be applied to the fabrication of a wide range of optical devices. Micro/nano-optical devices prepared by femtosecond laser direct writing in crystals have been applied in a broad range of applications in different wavelengths. PMN-PT crystal with relaxed ferroelectric has attracted much attention in recent years for its superior piezoelectric property and large electromechanical coupling coefficient, and its application in the infrared band is more prominent, so the fabrication of the optical devices based on PMN-PT crystal has gradually become a relevant research hotspot. The LIPSS is one of the micro/nano-structures that can be processed by femtosecond laser direct writing. The LIPSS is prevalent in many materials and has been found in metals, semiconductors, dielectrics, etc. Similarly, LIPSS can be induced by femtosecond lasers in PMN-PT crystal. The LIPSS has a wide range of applications in the fields of anti-reflectivity, permanent coloration, and wettability. Nevertheless, the physical processes and the mechanisms involved in the formation of LIPSS have different interpretations in different materials. In this paper, we describe the LIPSS induced by femtosecond laser on the surface of the PMN-PT crystal and characterize it theoretically. We have achieved a change in the period of the LIPSS from 750 nm to 3000 nm after experimenting with different laser parameters. Afterward, we simultaneously obtained the phase transition of the LIPSS in PMN-PT crystal through temperature modulation, and this phase transition can be analyzed by the variation of the Raman spectra. At the same time, we have obtained the Curie temperature for the LIPSS structure that is approximately 10 ℃ lower than that of the PMN-PT crystal and have analyzed the phase transition process through the structural properties of the PMN-PT crystal. The results of our experiments and analyzes on the LIPSS in PMN-PT crystal reported in this paper can provide some experience for the subsequent development of the optical devices related to the LIPSS in PMN-PT crystal.
飞秒激光直写 表面周期结构 PMN-PT晶体 相变 femtosecond laser direct writing LIPSS PMN-PT crystal phase transition
Author Affiliations
Abstract
1 Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
2 State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
Currently, supra-wavelength periodic surface structures (SWPSS) are only achievable on silica dielectrics and silicon by femtosecond (fs) laser ablation, while triangular and rhombic laser induced periodic surface structures (LIPSS) are achievable by circularly polarized or linear cross-polarized femtosecond laser. This is the first work to demonstrate the possibility of generating SWPSS on Sn and triangular and rhombic LIPSS on W, Mo, Ta, and Nb using a single linearly polarized femtosecond laser. We discovered, for the first time, SWPSS patches with each possessing its own orientation, which are completely independent of the light polarization direction, thus, breaking the traditional rules. Increasing the laser power enlarges SWPSS periods from 4-6 μm to 15-25 μm. We report a maximal period of 25 μm, which is the largest period ever reported for SWPSS, ~10 and ~4 times the maximal periods (2.4 μm/6.5 μm) of SWPSS ever achieved by fs and ns laser ablation, respectively. The formation of triangular and rhombic LIPSS does not depend on the laser (power) or processing (scan interval and scan methodology) parameters but strongly depends on the material composition and is unachievable on other metals, such as Sn, Al, Ti, Zn, and Zr. This paper proposes and discusses possible mechanisms for molten droplet generation/spread/solidification, Marangoni convection flow for SWPSS formation, and linear-to-circular polarization transition for triangular and rhombic LIPSS formation. Reflectance and iridescence of as-prepared SWPSS and LIPSS are characterized. It was found that besides insufficient ablation on W, the iridescence density of Ta-, Mo-, Nb-LIPSS follows the sequence of melting temperatures: Ta > Mo > Nb, which indicates that the melting temperature of metals may affect the regularity of LIPSS. This work may inspire significant interest in further enriching the diversity of LIPSS and SWPSS.
LIPSS SWPSS femtosecond laser antireflectance triangular LIPSS iridescence rhombic LIPSS International Journal of Extreme Manufacturing
2022, 4(1): 015102
Author Affiliations
Abstract
1 State Key Laboratory of Precision Spectroscopy, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China
2 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
3 State Key Laboratory of Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
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Over the past two decades, femtosecond laser-induced periodic structures (femtosecond-LIPSs) have become ubiquitous in a variety of materials, including metals, semiconductors, dielectrics, and polymers. Femtosecond-LIPSs have become a useful laser processing method, with broad prospects in adjusting material properties such as structural color, data storage, light absorption, and luminescence. This review discusses the formation mechanism of LIPSs, specifically the LIPS formation processes based on the pump-probe imaging method. The pulse shaping of a femtosecond laser in terms of the time/frequency, polarization, and spatial distribution is an efficient method for fabricating high-quality LIPSs. Various LIPS applications are also briefly introduced. The last part of this paper discusses the LIPS formation mechanism, as well as the high-efficiency and high-quality processing of LIPSs using shaped ultrafast lasers and their applications.
laser-induced periodic structures (LIPSs) formation mechanisms femtosecond pulse shaping pump-probe imaging structural color birefringent effects optical absorption photoluminescence Opto-Electronic Science
2022, 1(6): 220005
Author Affiliations
Abstract
1 Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
2 RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
3 School of Aeronautics and Astronautics, Sun Yat-sen University, Guangzhou 510275, China
4 State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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Orientations of laser induced periodic surface structures (LIPSS) are usually considered to be governed by the laser polarization state. In this work, we unveil that fluid dynamics induced by femtosecond (fs) laser ablation in liquid (fs-LAL) can easily break this polarization restriction to produce irregular circular-LIPSS (CLIPPS) and crisscross-LIPSS (CCLIPSS). Fs laser ablation of silicon in water shows formation of diverse LIPSS depending on ablation conditions. At a high power of 700 mW (repetition rate of 100 kHz, pulse duration of 457 fs and wavelength of 1045 nm), single/twin CLIPSS are produced at the bottom of macropores of several microns in diameter due to the formation of strong liquid vortexes and occurrence of the vortex shedding effect. Theoretical simulations validate our speculation about the formation of liquid vortex with an ultrahigh static pressure, which can induce the microstructure trenches and cracks at the sidewalls for fs-LAL of Si and tungsten (W) in water, respectively. At a low power of 50 mW, weak liquid vortexes are produced, which only give birth to curved LIPSS in the valleys of grooves. Consequently, it is deduced that liquid vortex plays a crucial role in the formation of macropores. Mountain-like microstructures induce complex fluid dynamics which can cause the formation of CCLIPSS on them. It is believed that liquid vortexes and fluid dynamics presented in this work open up new possibilities to diversify the morphologies of LIPSS formed by fs-LAL.
circular LIPSS crisscross LIPSS laser ablation in liquid femtosecond laser ablation in water liquid vortex vortex shedding Opto-Electronic Advances
2022, 5(2): 210066
红外与激光工程
2022, 51(2): 20210911
Author Affiliations
Abstract
1 RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
2 Innovative Photon Manipulation Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan
3 Metamaterials Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
In this study, we demonstrate a technique termed underwater persistent bubble assisted femtosecond laser ablation in liquids (UPB-fs-LAL) that can greatly expand the boundaries of surface micro/ nanostructuring through laser ablation because of its capability to create concentric circular macrostructures with millimeter-scale tails on silicon substrates. Long-tailed macrostructures are composed of layered fan-shaped (central angles of 45°–141°) hierarchical micro/nanostructures, which are produced by fan-shaped beams refracted at the mobile bubble interface (?50° light tilt, referred to as the vertical incident direction) during UPB-fs-LAL line-by-line scanning. Marangoni flow generated during UPB-fs-LAL induces bubble movements. Fast scanning (e.g. 1mms-1) allows a long bubble movement (as long as 2mm), while slow scanning (e.g. 0.1mms?1) prevents bubble movements. When persistent bubbles grow considerably (e.g. hundreds of microns in diameter) due to incubation effects, they become sticky and can cause both gas-phase and liquidphase laser ablation in the central and peripheral regions of the persistent bubbles. This generates low/high/ultrahigh spatial frequency laser-induced periodic surface structures (LSFLs/HSFLs/ UHSFLs) with periods of 550–900, 100–200, 40–100 nm, which produce complex hierarchical surface structures. A period of 40 nm, less than 1/25th of the laser wavelength (1030 nm), is the finest laser-induced periodic surface structures (LIPSS) ever created on silicon. The NIR-MIR reflectance/transmittance of fan-shaped hierarchical structures obtained by UPB-fs-LAL at a small line interval (5 μm versus 10 μm) is extremely low, due to both their extremely high light trapping capacity and absorbance characteristics, which are results of the structures’ additional layers and much finer HSFLs. In the absence of persistent bubbles, only grooves covered with HSFLs with periods larger than 100 nm are produced, illustrating the unique attenuation abilities of laser properties (e.g. repetition rate, energy, incident angle, etc) by persistent bubbles with different curvatures. This research represents a straightforward and cost-effective approach to diversifying the achievable hierarchical micro/nanostructures for a multitude of applications.
hierarchical micro/nanostructures persistent bubble femtosecond laser surface structuring beam refraction fan-shaped microstructure LIPSS International Journal of Extreme Manufacturing
2020, 2(1): 015001
1 上海交通大学化学化工学院, 上海 200240
2 上海交通大学分析测试中心, 上海 200030
在100 ℃, 150 ℃和270 ℃下固化得到了四种聚酰亚胺薄膜, 薄膜的固化温度对其性能有重要影响。 采用波长把5 nm的偏振紫外脉冲激光,在四种聚酰亚胺薄膜表面成功制备了纳米微条纹结构, 并研究了固化温度对微结构的形成过程及其形态的影响。
激光诱导周期表面结构(L1PSS) 聚酰亚胺薄膜 紫外激光 Nd:YAG激光器