Due to the unique ultra-short pulse duration and high peak power, femtosecond (fs) laser has emerged as a powerful tool for many applications but has rarely been studied for 3D printing. In this paper, welding of both bulk and powder materials is demonstrated for the first time by using high energy and high repetition rate fs fiber lasers. It opens up new scenarios and opportunities for 3D printing with the following advantages - greater range of materials especially with high melting temperature, greater-than-ever level of precision (sub-micron) and less heat-affected-zone (HAZ). Mechanical properties (strength and hardness) and micro-structures (grain size) of the fabricated parts are investigated. For dissimilar materials bulk welding, good welding quality with over 210 MPa tensile strength is obtained. Also full melting of the micron-sized refractory powders with high melting temperature (above 3000 degree C) is achieved for the first time. 3D parts with shapes like ring and cube are fabricated. Not only does this study explore the feasibility of melting dissimilar and high melting temperature materials using fs lasers, but it also lays out a solid foundation for 3D printing of complex structure with designed compositions, microstructures and properties. This can greatly benefit the applications in automobile, aerospace and biomedical industries, by producing parts like nozzles, engines and miniaturized biomedical devices.
We report on multimodal depth-resolved imaging of unstained living Drosophila Melanogaster larva using sub-50 fs pulses centered at 1060 nm wavelength. Both second harmonic and third harmonic generation imaging modalities are demonstrated.
A Yb fiber oscillator producing high-energy femtosecond pulse clusters is reported. Visualized by averaging autocorrelation, the output pulses consist of femtosecond pulse clusters that appear as a picosecond envelope with a ∼100-fs pulse in its center. Using more than 200-m fiber, the pulse energy is scaled up to 450 nJ. This high energy in a cluster of femtosecond pulses enables an important application—laser-induced breakdown spectroscopy.
An Yb fiber laser oscillator with sub-30 fs pulses compressed by MIIPS is tested for multiphoton
microscopy. It leads to greatly improved third harmonic generation images. Multiphoton fluorescence,
second and third harmonic generation modalities are compared on stained microspheres and unstained