High-NA aberration-free ultrafast laser processing in depth of glass

Compensation for spherical aberration by 0.8NA focusing ultrafast pulse laser beams in media at depth up to 4 mm is a crucial technique in writing waveguides, nanostructuring, selective laser etching, optical data storage, slicing SiC. A suggested solution is aplanatic objective with function of compensating for spherical aberration, equipped with a replaceable protective window and capable to operate with various materials at 1030nm and 515nm. Over- and under-compensation of spherical aberration allows providing specific processing effects. The paper presents an analysis of high NA focusing inside a transparent medium at different depths, and experimental results for writing waveguides.