Adding chemically selective subtraction to multi-material 3D additive manufacturing.

Existing photoresists for 3D laser lithography that can be removed after development in a subtractive manner typically suffer from harsh cleavage conditions. Here, we report chemoselectively cleavable photoresists for 3D laser lithography based on silane crosslinkers, allowing the targeted degradation of 3D printed microstructures under mild conditions. Three bifunctional silane crosslinkers carrying various substitutions on the silicon atom are synthesized.

On the determination of χ in thin films: a comparison of one-beam second-harmonic generation measurement methodologies.

The determination of the second-order susceptibility (χ) of thin film samples can be a delicate matter since well-established χ measurement methodologies such as the Maker fringe technique are best suited for nonlinear materials with large thicknesses typically ranging from tens of microns to several millimeters. Here we compare two different second-harmonic generation setups and the corresponding measurement methodologies that are especially advantageous for thin film χ characterization. This exercise allows for cross-checking the χ obtained for identical samples and identifying the main sources of error for the respective techniques.

Enhancement of second-harmonic generation in nonlinear nanolaminate metamaterials by nanophotonic resonances.

Nanolaminate metamaterials recently attracted a lot of attention as a novel second-order nonlinear material that can be used in integrated photonic circuits. Here, we explore theoretically and numerically the opportunity to enhance the nonlinear response from such nanolaminates by exploiting Fano resonances supported in grating-coupled waveguides. The enhancement factor of the radiated second harmonic signal compared to a flat nanolaminate can reach values as large as 35 for gold gratings and even 7000 for MgF gratings.