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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 to 10. Moreover, a Y-splitter was realized to demonstrate the potential of this process.

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We present THz ultrashort pulse detection by a photoconductive antenna array consisting of 16 photoconductive antennas. The efficient excitation of the photoconductive antennas has been realized by a microlens array which generates 16 single spots from the exciting fs-laser beam. This combination of optoelectronics and microoptics improves the detection efficiency by an order of magnitude in comparison to an excitation by a line focus.

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