G. Matthäus, H. Kämmer, K. A. Lammers, C. Vetter, W. Watanabe, and S. Nolte, "Inscription of silicon waveguides using picosecond pulses," Opt. Express 26, 24089 (2018).
Direct writing of single-mode waveguides into crystalline silicon using ps laser pulses is presented. The embedded structures were fabricated by moving the focal position along the beam axis with the help of a long distance microscope objective. In situ monitoring during inscription was performed to analyze the processing dynamics. The waveguide generation is based on pronounced multi-pulse interaction at moderate pulse energies around 100 nJ. All samples were characterized in terms of mode field distribution and damping losses. Calculations indicate an induced refractive index change in the range of 10−3 to 10−2. Moreover, a Y-splitter was realized to demonstrate the potential of this process.