Multispot writing in molten quartz

Nature photonics selected one of the most recent publications from the MBI's ongoing collaboration with the Jean Monnet University of Saint Etienne, France, as one of its research highlights. We cite "Multispot writing in fused glass", Opt., Express 17, 3531-3542 (2009). Due to its highly deterministic and nonlinear absorption process, laser writing with infrared femtosecond lasers offers the possibility of generating embedded, localized structural changes in transparent materials. By moving the sample with respect to the laser focus, three-dimensional structures can be inscribed. However, the fabrication of complex structures often requires a long processing time. As C. Mauclair and his colleagues from France and Germany have shown, the speed problem can be solved by parallel processing using multiple laser spots with adjustable patterns. The trick is to use a periodic binary phase mask to spatially modulate the wavefront of the laser beam. By varying the period of the binary phase, the team was able to show that a simple lattice-phase mask enables dynamic dual-spot machining. A liquid crystal modulator was used which was optically driven to produce a binary phase mask. For processing, a Ti: Sa laser with a pulse duration of 150 fs, a wavelength of 800 nm, the repetition frequency of 10 kHz and a power of 30 mW was used. By controlling sample movement, the team successfully enrolled three-dimensional waveguide structures such as splitters and wavelength demultiplexers in molten quartz. The team members are confident that enough energy will increase the number of foci working on them.