| Abstract [eng] |
One of the most common substances in photonics is lithium niobate. Due to its exceptional chemical properties, such as high electro-optical, acousto-optical, piezoelectric coefficients, the material is used in the production of photonic crystals and optical media. The formation of micro and nano structures is very important for the production of such devices. By using femtosecond laser pulses and selective chemical etching, it is possible to form high-quality microchannels in glasses and crystals. When these processes are combined, the material is etched only in the laser-modified areas. The etching of these structures is more than 60 times faster than that of an unmodified surface. Due to the wide range of application areas of the process, there is a need to improve this method and to look for the most optimal parameters. The aim of this work is to investigate the differences when the plates of lithium niobate are modified using high repetition rate Yb: KGW femtosecond laser using its first and second harmonic pulses, different polarizations (p, s, circular) and pulse durations and then etching those zones with suitable chemical etchants. The parameters of the modifying laser pulses are changed to determine their optimal values, which can ensure the highest etching speed and the highest quality. After the study was done it was determined that the optimal modification parameters are: 1,5 μJ pulse energy, scanning speed 1,5 mm/s, p polarization, 1st harmonic radiation with a pulse duration of 500 fs. Using these parameters, the highest average etching rate is achieved. It has also been found that in almost all cases, the lowest scanning speed is optimal because the highest quality nano structures are formed in the material. |
