Mask-free construction of three-dimensional silicon structures by dry etching assisted gray-scale femtosecond laser direct writing

Liu, Xueqing; Lei, Yu; Chen, Qi‐Dai; Sun, Hong–Bo

doi:10.1063/1.4977562

Cited by 26 publications

(13 citation statements)

References 34 publications

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“…The laser pulse energy was controlled by a gradient‐transmittance attenuator and the number of laser pulses was set by a mechanical shutter. After femtosecond laser modification, a modified region was formed around the micropits at the energy deposition locus with the formation of nanocracks, stress transformation of lattice, or change of chemical structure . Due to the nonlinear laser–matter interaction, femtosecond laser can modify almost any hard materials when laser pulse energy larger than the damage threshold of materials.…”

Section: Resultsmentioning

confidence: 99%

Optical Nanofabrication of Concave Microlens Arrays

Liu

Lei

Yang

et al. 2019

Laser & Photonics Reviews

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For the simple and versatile fabrication of nanosmooth finished microlens arrays on hard materials, an approach combining femtosecond laser modification with subsequent ion beam etching is demonstrated. This method is based on the dependence of the plasma etching rate on the laser fluence used to modify the surface. The fabricated microlenses exhibit a low surface roughness of approximately 2.5 nm, due to the high precision of the plasma etching and benefit from the smooth interface between the laser‐modified and pristine subsurface regions. Microlenses with focal lengths ranging from 60 to 100 µm are realized by controlling the laser fluence, exposure dose, and etching time. Uniform square and hexagonal microlens arrays are fabricated on both hard and ultrahard materials and glasses (fused silica, GaAs, SiC, diamond) by the same process and deliver high‐quality focusing and imaging.

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Section: Resultsmentioning

confidence: 99%

Optical Nanofabrication of Concave Microlens Arrays

Liu

Lei

Yang

et al. 2019

Laser & Photonics Reviews

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“…Then, 3D microstructures can be fabricated on silicon wafer after suitable dry etching conditions. Based on this principle, Liu et al 104 verified the feasibility of the dry-etching-assisted femtosecond laser gray-scale modification technology by successful fabrication of complex 3D microstructures on silicon wafer. For example, the 2D Fresnel zone plate pattern (Fig.…”

Section: Dry-etching-assisted Femtosecond Laser Modificationmentioning

confidence: 99%

“…As the ratio of etching rate between silicon and silica is about 10:1 when etched by fluorine-based gas 102,103 , the laser modified pattern can be used as the mask for 3D microstructures transferring 63 . More interestingly, the ability of etching resistant of laser modified region is greatly related to the concentration of oxygen atoms which can be adjusted by laser parameters 104 . Therefore, gray-scale 2D patterns with a concentration of oxygen atoms change with in-site position by femtosecond laser modification.…”

Section: Dry-etching-assisted Femtosecond Laser Modificationmentioning

confidence: 99%

Etching-assisted femtosecond laser modification of hard materials

Liu

Bai

Chen

et al. 2019

Opto-Electronic Advances

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With high hardness, high thermal and chemical stability and excellent optical performance, hard materials exhibit great potential applications in various fields, especially in harsh conditions. Femtosecond laser ablation has the capability to fabricate three-dimensional micro/nanostructures in hard materials. However, the low efficiency, low precision and high surface roughness are the main stumbling blocks for femtosecond laser processing of hard materials. So far, etching-assisted femtosecond laser modification has demonstrated to be the efficient strategy to solve the above problems when processing hard materials, including wet etching and dry etching. In this review, femtosecond laser modification that would influence the etching selectivity is introduced. The fundamental and recent applications of the two kinds of etching assisted femtosecond laser modification technologies are summarized. In addition, the challenges and application prospects of these technologies are discussed.

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“…Similar to FLWE, the microfabrication of MLAs by femtosecond laser dry etching (FLDE) technique also consists of two steps. [133,134] Liu et al fabricated microlenses with controllable diameter and sag height by this method. [25] As shown in Figure 9c, the silicon substrate was irradiated by the focused laser beam to form an array of ablated craters.…”

Section: Femtosecond Laser Wet Etching Technique (Flwe) Techniquementioning

confidence: 99%

Bioinspired Artificial Compound Eyes: Characteristic, Fabrication, and Application

Yang

Bian

et al. 2021

Adv Materials Technologies

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the visual nerve perception. This type of eyes has ultrahigh resolution, which can get clear image information. Inspired by this imaging system, people have put significant efforts over a long time for development of camera-related optical system for various applications, such as endoscope, digital camera, smartphones, robot eyes, visual implants. [7][8][9][10] Because of the rapid progress in micro/nano technologies, the artificial eyes structures can achieve extremely high resolution that is close to or even exceeding the human eye. However, the low field of view (FOV) (the maximum value is only 90°) hinders its wider applications. To solve this problem, multiple cameras need to be put together to work, which not only increases the cost, but also makes the entire optical system cumbersome. Hence, an optical device with portable, integrated, and large FOV features is highly desired.Different from the single-lens eyes, the insect eyes adopt another visual system. Figure 1b shows a honeybee's apposition compound eye, which has thousands of ommatidia arranged on a curved surface so that each ommatidium points in different directions. [11] Each unit consists of a lens, a crystalline cone, and a rhabdom. The focused light signal is transmitted to the photosensitive area by the crystalline cone, and then visual perception is generated after passing through the rhabdom. Each of the ommatidium can image which enables the insects to obtain sufficient information in a complex environment and exhibits the characteristics of large FOV, low aberration, and high sensitivity to moving objects. [12] In addition to the honeybee's compound eyes, the eyes of other insects in nature, such as mosquito eye, [13] fly's eye, [14] moth's eye, [15] and dragonfly's eye [16] also have similar structure and have attracted much attention due to the deep research on bionics. [4,9,12,[17][18][19][20][21] The characteristics of the compound eyes in nature and the advanced micro/nano-processing technologies provide great technical support and inspiration for the researchers to prepare artificial compound eyes (ACEs) with close-packed microlens arrays (MLAs) as optical imaging elements. [22][23][24][25][26][27][28][29][30] Such MLAs compose of microscale lenses with the same surface feature and the regular arrangements are important microoptical components. The great light field (LF) regulation and focusing abilities of MLAs have made it essentially in various applications such as imaging, [31][32][33][34][35][36][37][38][39] dynamic target capture, [40][41][42] beaming homogenizing, [43][44][45][46] sensing, [47][48][49] light extractionThe natural compound eyes provide great inspiration for design of advanced imaging devices. Artificial compound eyes (ACEs) with close-packed microlens arrays (MLAs) have attracted enormous research interests due to their remarkable advantages in modern micro-optical systems, such as miniaturization, high integration, tunable focal length, large field of view, and moving objects tracking. Over a decade of intens...

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Mask-free construction of three-dimensional silicon structures by dry etching assisted gray-scale femtosecond laser direct writing

Cited by 26 publications

References 34 publications

Optical Nanofabrication of Concave Microlens Arrays

Optical Nanofabrication of Concave Microlens Arrays

Etching-assisted femtosecond laser modification of hard materials

Bioinspired Artificial Compound Eyes: Characteristic, Fabrication, and Application

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