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Nonlinear Optics || Ultrafast and Intense-Field Nonlinear Optics
摘要： There is currently great interest in the physics of ultrashort laser pulses. Recent advances have led to the generation of laser pulses with durations of the order of 1 attosecond (Hentschel et al., 2001). Ultrashort pulses can be used to probe the properties of matter on extremely short time scales. Within the context of nonlinear optics, ultrashort laser pulses are of interest for at least two separate reasons. The ?rst reason is that the nature of nonlinear optical interactions is often profoundly modi?ed through the use of ultrashort laser pulses, in part because of the broad spectral bandwidth necessarily associated with such pulses. The next two sections of this chapter treat various aspects of the resulting modi?cations of the nature of nonlinear optical interactions. The second reason is that ultrashort laser pulses tend to possess extremely high peak intensities (because laser pulse energies tend to be established by the energy-storage capabilities of laser gain media), and thus short laser pulses tend to have much higher peak powers than longer pulses. The second half of this chapter is devoted to a survey of the sorts of nonlinear optical processes that can be excited by extremely intense laser ?elds.
关键词： attosecond pulses,ultrashort laser pulses,high peak intensities,spectral bandwidth,nonlinear optics
更新于2025-09-23 15:21:01
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[Laser Institute of America ICALEO? 2014: 33rd International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - San Diego, California, USA (October 19–23, 2014)] International Congress on Applications of Lasers & Electro-Optics - Laser microjet? cutting of up to 3 mm thick sapphire
摘要： The Laser Microjet? is a world-wide patented technology which uses ns-laser pulses which is guided to the work piece in a water jet. The sample is therefore cooled by the water and thermal damage during cutting is reduced which is relevant for metals and semiconductor materials. For the case of sapphire cutting this leads to lower thermal load of the samples and therefore no cracking during cutting. Sapphire cutting was until now not possible with the Laser Microjet? although it is used for micro machining of a lot of other materials like semiconductors, metals, diamond and ceramics. Cutting up to 3 mm thick sapphire with parallel walls with a roughness of < 0.5 μm and a kerf width of < 100 μm is achieved. The cutting speed of up to 0.1 mm/s for 1 mm samples has been achieved. The cut samples exhibit parallel walls which is a big advantage of the Laser Microjet? technology compared to other laser cutting technologies, not only for sapphire. The edges at the front side exhibit high quality with a radius of curvature of less than 20 μm and without any chipping. The back side quality still needs to be improved although chips with less than < 20 μm are already achievable. For laser cutting of sapphire high peak intensities are required in order to reach sufficient high absorption of the laser radiation and achieve material ablation. The process is not yet fully understood. It is expected that the water jet interaction with the material plays an important role together with laser light-material interaction. The geometry of the kerf of the work piece has a strong influence on the cutting process. Water jet interruptions due to e.g. non planar surfaces lead to loss of energy on the way to the work piece and therefore interruption of the absorption and ablation process. That is why certain processing strategies are necessary to achieve cutting for samples with the thickness of 3 mm. We expect to be able to cut even thicker samples of > 5 mm as well as further improve the backside edge quality in the future.
关键词： high peak intensities,thermal damage reduction,water jet coupled laser,Laser Microjet?,sapphire cutting
更新于2025-09-19 17:13:59