Micromachining of Diffractive Optical Elements Embedded in Bulk Fused Silica by Nanosecond Pulses

Micro-optical devices embedded in transparent materials are usually manufactured focusing a pulsed laser in bulk fused silica. Under this condition, pulsewidth becomes the most important parameter that rules the size of the inscriptions. Ultrafast pulses (pico- and femtosecond pulses) avoid thermal effects and the results present a high efficiency. Nevertheless, nanosecond lasers are more available due the reduced costs. Therefore, a study of the optical behavior of embedded elements micromachined by nanosecond pulses is required. In this study, we show that this regime of pulses can still be used for engraving diffractive optical elements in transparent materials, regardless of the thermal damage. A Fresnel zone plate and a far-field beam shaper have been manufactured as an example of the functionality of these devices.