Femtosecond laser micromachining of diamond: Current research status, applications and challenges

Abstract

Ultra-fast femtosecond (fs) lasers provide a unique technological opportunity to precisely and efficiently micromachine materials with minimal thermal damage owing to the reduced heat transfer into the bulk of the work material offered by short pulse duration, high laser intensity and focused optical energy delivered on a timescale shorter than the rate of thermal diffusion into the surrounding area of a beam foci. There is an increasing demand to further develop the fs-machining technology to improve the machining quality, minimize the total machining time and increase the flexibility of machining complex patterns on diamond. This article offers an overview of recent research findings on the application of fs-laser technology to micromachine diamond. The laser technology to precisely micromachine diamond is discussed and detailed, with a focus on the use of fs-laser irradiation systems and their characteristics, laser interaction with various types of diamonds, processing and the subsequent post-processing of the irradiated samples and, appropriate sample characterisation methods. Finally, the current and emerging application areas are discussed, and the challenges and the future research prospects in the fs-laser micromachining field are also identified.

Transformations of fast neutron-irradiated diamonds under femtosecond laser radiation

“…This fact allows us to neglect the thermal effect of single shot femtosecond UV laser treatment on the structure and optical properties of neutron-irradiated diamond in the bulk of the sample under study. The boson peak near 400 cm -1 [11] is also clearly visible in the Raman spectra measured in the spots of laser graphitization, which made it possible to determine the thickness of the graphitized layer (figure 2 (c)) by the method described in [15].…”

“…The initial spectrum of a neutron-irradiated sample is a typical spectrum of radiation-damaged diamond with partial or complete amorphization [12]. Their spectra may lack the diamond peak at 1332 cm -1 , and the shape of the spectrum is determined by the phonon confinement effect with an intense boson peak near 400 cm -1 [11] (spectrum 1 at figure 1 (b)). Irradiation by UV laser pulses heats the surface of the sample and induces structural changes, which are observed in the Raman spectra in the form of intense D-and G-peaks [13], whose position and FWHM (full width at half maxima) change along the surface of the graphitized region.…”

“…The aim of this work is to investigate the graphitization of single-crystal diamond irradiated with fast reactor neutrons under the influence of intense femtosecond UV laser pulses. The advantage of using ultrashort pulses is the high locality of the action with minimal expansion of the graphitized area due to heat diffusion [11]. At the same time, unlike thermal heating in air, a thin graphite-like layer remains on the diamond surface without having time to oxidize.…”

Laser Ablated Nanocrystalline Diamond Membrane for Infrared Applications

“…To create an optical element entirely based on nanocrystalline diamond film, precise tools for its microprocessing are required. One of these tools is laser radiation, which is proven to be an effective instrument for creating elements of photonics and electronics based on diamond [ 27 , 28 ]. As a result of local laser action, graphitized material is formed on the surface or in the bulk of a diamond (depending on irradiation conditions).…”

Laser-Induced Graphitization of Diamond Under 30 fs Laser Pulse Irradiation

“…[8][9] However, it is known that pulses as short as 100 fs still thermalise electrons and generate hot ions and phonons leading to thermal quenching and sp 3 lattice relaxation in diamond. 7,[10][11][12] It has been postulated that pulses shorter than 50 fs display primarily non-thermal characteristics as photo-ablation and structural re-organisation is predominantly driven by photo-ionization of electrons. 10,13 The sub-50 fs regime still remains largely unexplored for processing of diamond.…”