Deterministic laser nanomachining in glass

Femtosecond laser direct writing has emerged as a powerful tool for fabricating innovative 3D functional structures in transparent materials, such as microresonators, optical waveguides, microfluidic channels, microelectrodes and micromechanics [1]. The feature sizes of the fabricated structures are typically on the micrometer scale due to the difficulties in substantially breaking the diffraction limit. Here, we demonstrate fabrication of 3D nanostructures deeply buried inside glass in a controllable manner [2]. Specifically, we fabricate nanofluidic channels with a width of ~40 nm and use the fabricated nanochannels to perform single DNA molecule analysis. Our technique is based on excitation of self-induced plasmonic waves within glass using an ultrafast laser beam, which is revealed by observing the gradual formation of the nanostructure under the continuous irradiation of multiple femtosecond laser pulses [3]. The unique characteristic allows fundamentally breaking the diffraction limit in the far-field optical nanofabrication and opens up opportunities for innovative applications such as 3D metamaterials.