Flexible Microstructuring of Thin Films Using Multi-beam Interference Ablation with Ultrashort Lasers

Interference of laser beams with the high pulse energy opens an opportunity to direct structuring over large areas. We report results of the laser beam interference ablation (LBIA) of thin metal films on the glass substrate irradiated with picosecond and nanosecond lasers. The laser beam was split into four and six beams by using the diffractive optical element. The 4F imaging system was used to produce interference pattern on the surface of the metal film. Regular structures with a period of 5 m were produced in thin films of various metals which can be used for filtering infrared or terahertz radiation. The structure was extended by translation of the workpiece between laser pulses. Interference of multiple laser beams is capable of forming a variety of interference patterns, while selection of the laser wavelength as well as imaging optics open possibilities to control the period of the structures down to the sub-micrometer range.