Experimental and numerical optimization of beam shapes for short-pulse ultraviolet laser cutting processing

AbstractIn this work the effect of elliptical beam shapes on cutting performance of silicon is studied experimentally using a Diode Pumped Solid State Q-switched UV laser operating at the wavelength of 355 nm. Elliptical beams are investigated by varying scanning speed, repetition rate and average output power. It is shown that a short elliptical beam with 6×230 μm dimension forms a deeper groove at higher cutting speed and lower average output power compared to a longer elliptical beam. A numerical model of the laser cutting process is also described. Some validation results for single and multi-pulse cutting are shown

Smart antimicrobial efficacy employing pH-sensitive ZnO-doped diamond-like carbon coatings

One of the main challenges in endoprosthesis surgeries are implant-associated infections and aseptic-loosenings, caused by wear debris. To combat these problems, the requirements to surfaces of endoprostheses are wear-resistance, low cytotoxicity and antimicrobial efficacy. We here present antimicrobial coatings with a smart, adaptive release of metal ions in case of infection, based on ZnO-nanoparticles embedded in diamond-like carbon (DLC). The Zn2+ ion release of these coatings in aqueous environments reacts and adapts smartly on inflammations accompanied by acidosis. Moreover, we show that this increased ion release comes along with an increased toxicity to fibroblastic cells (L929) and bacteria (Staphylococcus aureus subsp. aureus, resistant to methicillin and oxacillin. (ATCC 43300, MRSA) and Staphylococcus epidermidis (ATCC 35984, S. epidermidis). Interestingly, the antimicrobial effect and the cytotoxicity of the coatings increase with a reduction of the pH value from 7.4 to 6.4, but not further to pH 5.4

Waveguide-plasmon polaritons enhance transverse magneto-optical Kerr effect

Magneto-optical effects in ferrimagnetic or ferromagnetic materials are usually too weak for potential applications. The transverse magneto-optical Kerr effect (TMOKE) in ferromagnetic films is typically on the order of 0.1%. Here, we demonstrate experimentally the enhancement of TMOKE due to the interaction of particle plasmons in gold nanowires with a photonic waveguide consisting of magneto- optical material, where hybrid waveguide-plasmon polaritons are excited. We achieve a large TMOKE that modulates the transmitted light intensity by 1.5%, accompanied by high transparency of the system. Our concept may lead to novel devices of miniaturized photonic circuits and switches, which are controllable by an external magnetic field

Low 1f noise single-layer YBa2Cu3Ox dc SQUID at 77 K

Low 1f noise single-layer YBa2Cu3Ox dc SQUID at 77 K / B. Stritzker ... - In: Applied physics letters. 60. 1992. S. 3048-305