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Material Processing with Femtosecond Lasers
Published in Shalom Eliezer, Kunioki Mima, Applications of Laser–Plasma Interactions, 2008
One of the most important applications of the femtosecond laser pulses is the industrial application such as micromachining. Even with a small pulse energy, for example, 1 mJ, the femtosecond laser pulses give us high peak intensity. Depending on the intensity (W/cm2) or fluence (J/cm2), distinctive phenomena occur. Recent studies of femtosecond laser processing cover a wide variation of material like metal, semiconductor, and dielectric materials. For a transparent material such as glass, quartz, and wideband gap semiconductor, internal micromachining using multiphoton absorption is well known. However, we describe surface processing mainly for metals and semiconductors here.
Laser refractive surgery
Published in Pablo Artal, Handbook of Visual Optics, 2017
Jorge L. Alió, Mohamed El Bahrawy
Since the introduction of femtosecond refractive lasers in the year 2001, it had became a dominant part of the refractive techniques first as a flap fashioning modality, then as a dependent tool, in femtosecond refractive surgery, as Femtosecond Lenticular Extraction (FLEx) or Small Incision Lenticular Extraction (SMILE). The femtosecond laser is a focused infrared laser with a wavelength of 1053 nm that uses ultrafast pulses with a duration of 100 fs (100 × 10–15 s). It is a solid-state Nd:Glass laser similar to an Nd:YAG laser, which operates on the principle of photoionization (laser-induced optical breakdown), producing photodisruption at its focal point, resulting in a rapidly expanding cloud of free electrons and ionized molecules (plasma). Corneal flap creation in LASIK is the most common application of the femtosecond laser in corneal refractive surgery. More than 55% of all LASIK procedures in the United States were performed with femtosecond lasers in 2009 (Table 15.5). First described in 1996, laser intrastromal keratomileusis, was using picosecond laser, abd limiting the dependence on excimer laser as the sole tool of laser refractive surgery; these early trials required extensive manual dissection, leaving irregular interface. The shift to femtosecond laser, with the introduction of VisuMax in 2007, allowed much improved precision as an advantage over LASIK, as all of the potential variables associated with excimer laser ablation are avoided, such as stromal hydration, laser fluence, and environmental factors. Considering that the evolution of refractive surgery is heading closer to the preservation of corneal biomechanics to increase safety and achieve aberration-free results, also the new techniques had been proven to be more safe and effective in high myopic patients with limited postoperative dry eye syndrome and limited decrease in corneal sensation. So considering modern-day concepts of minimally invasive refractive surgery, FLEX and SMILE intrastromal keratomileusis techniques appear to be a reasonable technique worthy of future study and consideration.
Fabrication of GaAs micro-optical components using wet etching assisted femtosecond laser ablation
Published in Journal of Modern Optics, 2020
Xiaoyan Sun, Fang Zhou, Xinran Dong, Fan Zhang, Chang Liang, Lian Duan, Youwang Hu, Ji’an Duan
Gallium arsenide (GaAs) lasers have both high peak power and a modulated bandwidth, and it can be used for optical information transmission and laser rang finding. However, the laser divergence angle of GaAs lasers is large, and this results in a large transmission loss. The transmission efficiency of the GaAs laser can be improved if the laser is collimated with a micro-optical component. Therefore, it is necessary to study the preparation of GaAs micro-optical components. Femtosecond laser ablation is an important method for fabricating micro-optical components [1–7] and micro-electronic circuits. It can be used to process a variety of materials, including GaAs. Importantly, it can be used to fabricate complex three-dimensional micro-nanostructures on semiconductor materials and metal materials. However, the machining efficiency of femtosecond laser direct ablation is low, and the surface quality is also difficult to achieve[8–10].
Multiscale Investigation of Femtosecond Laser Pulses Processing Aluminum in Burst Mode
Published in Nanoscale and Microscale Thermophysical Engineering, 2018
Yiming Rong, Pengfei Ji, Mengzhe He, Yuwen Zhang, Yong Tang
Femtosecond laser owes the advantage of small collateral damage in fabricating precise microstructures over other long pulse lasers and continuum wave lasers. In the past decades, tremendous approaches were attempted to enhance the micro-/nano-fabrication quality and efficiency, which can be categorized from the laser side (such as tuning the laser parameters) [1–4] and the material side (such as pre-/post-processing the material with hybrid manufacture method) [5–8]. With the rapid development of femtosecond laser pulse source technology and approaches manipulating the pulse transportation, the high pulse repetition rate up to megahertz (MHz) and high power up to tens of watts can be achieved, enabling the efficient productivity of femtosecond laser fabrication from academic research to industrial applications [9].
A rapid precision fabrication method for artificial compound eyes
Published in International Journal of Optomechatronics, 2021
Yueqi Zhai, Jiaqi Niu, Jingquan Liu, Bin Yang
In the last decade, there has been tremendous improvement in the fabrication technologies of artificial compound eyes. Several approaches have been proposed, such as direct laser writing, thermal reflow of photoresist, self-assembly, microdroplet jetting and femtosecond laser aided wet or dry etching.[15–18] Despite considerable advances, these techniques still have certain drawbacks, such as high time consumption, high process complexity, lack of fabrication flexibility, and difficulties in consistence. Femtosecond lasers and precision machining are the two major ways for constructing concave structures directly on curved substrates currently available. Bian et al. proposed employing femtosecond laser-assisted wet etching directly on a curved glass substrate to construct 3000 ommatidia in 2016.[19] Femtosecond laser needs expensive experimental equipment and requires point-to-point scanning, which is time-consuming and labor-intensive. Moreover, the introduction of corrosive liquids, such as hydrofluoric acid into wet etching increases the danger of the experiment, and the corrosion rate and time cannot be precisely controlled. In 2019, Jin et al. used a two-photon polymerized femtosecond laser direct writing method to fabricate a curved SU-8 template that can be reused more than 50 times without deformation.[20] They prepared only 7 and 19 ommatidia in a much shorter time, verified the optical microscope imaging, but did not integrate it into a commercial complementary metal-oxide-semiconductor (CMOS) camera to form a miniature imaging system. And the number of compound eyes prepared is much lower than that of insects in nature. Compared to the compound eyes prepared by femtosecond laser processing, with the modernization of equipment, five-axis precision machining equipment can now efficiently and rapidly produce a wide variety of structures on flat, spherical, and aspheric surfaces.