In-Depth Optical Characterization of Femtosecond-Written Waveguides in Silicon

In‐Volume Laser Direct Writing of Silicon—Challenges and Opportunities

“…Using this approach, longitudinal inscription of waveguides has been demonstrated by inducing a seed on the exit surface. [ 20,23,25,225 ] This offers a unique possibility for simple writing of optical functional devices in silicon. Based on recent efforts concentrating on silicon and parallel advances in ultrafast laser technologies, its seems natural to expect at short term the deployment of laser 3D writing to even narrower band‐gap materials and other important semiconductors such as zinc selenide, [ 226 ] zinc sulfide, [ 227 ] and gallium phosphide.…”

“…have recently carried out in‐depth analyses of the waveguide profiles, that is, its refractive index distribution in the plane perpendicular to the optical axis . [ 225 ] This work relies on a comparison between experiments consisting of transversely‐shifted injection of continuous light in the waveguides in the plane, and calculations of the overlap integral together with the beam propagation in each situation. In this case, the waveguides showed losses of 8.7 dB cm.…”

Derivation of Luminescent Mesoporous Silicon Nanocrystals from Biomass Rice Husks by Facile Magnesiothermic Reduction

“…Therefore, the fabrication of Si nanocrystals has attracted tremendous attention in wide scientific and technologic communities because of their vast application fields in optoelectronics as well as electronics. For instance, nanofloating gate flash memory devices [ 8 , 9 , 10 , 11 ], field-effect electroluminescence devices [ 12 , 13 ], tandem solar cells [ 14 ], and optical waveguides [ 15 , 16 ] are typical examples that can use the quantum-confined electronic energy system in Si nanocrystals. Owing to the high porosity of Si nanocrystals, furthermore, they are also very useful as an active source material in energy storage and conversion devices.…”

Inscribing diffraction grating inside silicon substrate using a subnanosecond laser in one photon absorption wavelength

“…However, unlike glasses, difficulty has been reported to process inside silicon with an ultrafast laser in the transparent wavelength region 8 . Thus, special methods have been executed, such as use of optical setup with extremely high numerical aperture of 2.97 9 , double pulse 10 , and use of high repetition rate laser 11 – 13 . In the study by Matthäus et al 12 , waveguides were inscribed in longitudinal geometry starting at the exit surface then moved upstream, in this case the waveguide inscription was significantly facilitated by an imperfectly flat exit surface 13 .…”

“…Thus, special methods have been executed, such as use of optical setup with extremely high numerical aperture of 2.97 9 , double pulse 10 , and use of high repetition rate laser 11 – 13 . In the study by Matthäus et al 12 , waveguides were inscribed in longitudinal geometry starting at the exit surface then moved upstream, in this case the waveguide inscription was significantly facilitated by an imperfectly flat exit surface 13 . Very recently, it was reported that temporal contrast (pre/post-pulse, pedestal), which is laser technology dependent, of ultrafast laser pulses has a significant effect on the modification threshold energy 14 .…”