Shape control of microchannels fabricated in fused silica by femtosecond laser irradiation and chemical etching.

We report on the fabrication of shape-controlled microchannels in fused silica by femtosecond laser irradiation at 600 kHz repetition rate followed by chemical etching. The shape control is achieved by suitable wobbling of the glass substrate during the irradiation process. Cylindrical microchannels with uniform cross-sections are demonstrated with an unprecedented length of 4 mm. Some applications are also addressed: connection of two microchannels with a smaller one, 3D microchannel adapter and fabrication of O-grooves for easy fiber-to-waveguide coupling.