50-nanometer femtosecond pulse laser induced periodic surface structures on nitrogen-doped diamond

Abstract Ultrashort pulse laser interaction with nitrogen-doped type I-b diamond was investigated with near-infrared femtosecond laser pulses at repetition rates of 5 kHz and 11 MHz. High spatial frequency laser-induced periodic surface structures with periodicities of 50 and 200 nm were generated perpendicular to the polarization of the electric field. The novel 50 nm features are found to be due to a phase transition from crystalline diamond to a graphitic phase in contrast to the 200 nm laser-induced periodic surface structures consisting still of crystalline material.