Micro-machining of diamond, sapphire and fused silica glass using a pulsed nano-second Nd:YVO4 laser

Optically transparent materials are being found in an ever increasing array of technological ap-plications within industries such as automotive and communications. These industries are begin-ning to realize the importance of implementing surface engineering techniques to enhance sur-face properties of materials. On account of the importance of surface engineering, this paper de-tails the use of a relatively inexpensive diode-pumped solid state (DPSS) Nd:YVO4 laser to modi-fy the surfaces of fused silica glass, diamond and sapphire on a micrometre scale. Using threshold fluence analysis it was identified that, for this particular laser system, the threshold fluence for diamond and sapphire ranged between 10 Jcm-2 and 35 Jcm-2 for a laser wavelength of 355 nm, dependant on the cumulative effects arising from the number of incident pulses. Through optical microscopy and scanning electron microscopy it was found that the quality of processing, result-ing from the Nd:YVO4 laser, varied with each of the materials. For fused silica glass considerable cracking and deformation occurred. For the sapphire, good quality features were produced albeit with the formation of debris indicating the requirement for post-processing to remove the ob-served debris. The diamond material gave rise to the best quality results with extremely well de-fined micrometre features and minimal debris formation, comparative to alternative techniques such as femtosecond laser surface engineering.