Parallel laser fabrication of electrically conductive graphitic columns in diamond

An ultrashort pulsed laser focused beneath the surface of diamond can breakdown the lattice and induce graphite, and can hence be used for the fabrication of electrical connections embedded in the diamond bulk. In this work, an adaptive hologram displayed on a liquid crystal spatial light modulator is used to simultaneously generate multiple foci and correct for aberrations associated with refraction at the diamond interface. Arrays of graphitic columns are thus laser written with a single scan through the thickness of the diamond, improving fabrication times by more than an order of magnitude. The electrical characteristics of the fabricated structures are analyzed as a function of the number and lateral spacing of foci in an array, and compared with results where structures are fabricated sequentially with a single laser focus.