Reina Yoshizaki

The internal modification of glass using ultrashort pulse lasers has been attracting attention in a wide range of applications. However, the remarkably low processing speed has impeded its use in the industry. In this study, we achieved ultrafast internal modification of glass by coaxially focusing a single-pulse femtosecond laser and continuous-wave (CW) laser with the wavelength that is transparent to the glass. Compared with the conventional method, the processing speed increased by a factor

Transient and selective laser (TSL) processing is a method used for the rapid fabrication of transparent materials. In this method, electrons in glass are excited by an ultrashort-pulse laser. This electron-excited region selectively absorbs a long-pulse laser with low intensity, resulting in microfabrication. However, the mechanism of material removal during TSL processing is not completely understood. In this study, we measured the threshold of TSL processing in synthetic fused silica to inves

Optical waveguides are crucial in the development of integrated optical circuits. This study examines their formation in dielectric materials using ultrashort pulse laser direct writing. Emphasizing the significance of the processing parameters for writing low-loss waveguides, we explored the underlying mechanisms through in situ observations of internal modifications and a detailed analysis of electron density and refractive index changes. Employing a combination of pump-probe imaging and Mach-

A novel ultrashort pulse laser (USPL) surface ablation approach using spatial and temporal focusing (STF) is proposed to enable sub-microscale material removal during diamond processing. With the conventional method, it is difficult to achieve a sub-microscale material-removal depth by simply decreasing the pulse energy because of its nonlinearity with the pulse energy near the material-damage threshold. By precisely shaping the pulse durations in the laser beam waist, STF controlled the materia

Diamond is a promising material for advanced industrial applications such as optical components, semiconductor devices, and cutting tools due to its outstanding mechanical, thermal, and optical properties. However, these same properties make it extremely challenging to achieve both high shape accuracy and superior surface quality simultaneously. Although chemical mechanical polishing has been widely adopted and matured in practice, significant challenges remain, including limited capability for