We present and validate a new method for designing transmission gratings with high efficiency for the 1st diffraction order across the visible spectrum. The high efficiency is achieved by redirecting light to the 1st order via asymmetric composite elements, which scatter light in the same direction as the 1st diffraction order. By focusing on increasing the directional scattering of the grating elements, the design remains simple yet effective. As a result, the gratings are relatively easy to fabricate. Measurements of fabricated gratings show a relative increase of over 40% for a large part of the visible spectrum.

This thesis investigates how light can be manipulated through directional scattering by nanostructures, as an alternative to traditional methods such as lenses, mirrors, and diffraction gratings. Thanks to modern nanofabrication techniques, light scattering can be controlled by carefully designed nanostructures. In this work, a design method was developed for nanoparticles that scatter light preferentially in a specific direction by combining absorbing and non-absorbing materials, introducing a phase difference in the scattered field. Experimental results with silica–gold particles confirm the theoretical predictions. The theory was subsequently applied to transmission diffraction gratings, in which glass structures combined with metals or semiconductors were fabricated using techniques such as electron-beam lithography. Although metallic gratings exhibited reduced efficiency due to absorption, gratings made with titanium nitride showed the expected performance improvements.

We study the broadband scattering of light by composite nanoparticles through the Born approximation, FEM simulations, and measurements. The particles consist of two materials and show broadband directional scattering. From the analytical approach and the subsequent FEM simulations, it was found that the directional scattering is due to the phase difference between the fields scattered by of each of the two materials of the nanoparticle. To confirm this experimentally, composite nanoparticles were produced using ion-beam etching. Measurements of SiO₂ / Au composite nanoparticles confirmed the directional scattering which was predicted by theory and simulations.

We show that the scattering of light by a composite nanoparticle leads to directional scattering through the phase difference between the light scattered by each of the materials. The resulting scatter pattern is experimentally verified.

We show that composite nanoparticles can be designed to scatter light into a desired direction. By choosing the materials of the nanoparticle carefully, the phase of the scattered light by the different components can be controlled. This leads to constructive interference is certain directions and destructive interference in others, resulting in directional scattering obtainable for a large bandwidth. FEM simulations were used to validate the theory. Furthermore, SiO2/Au nanoparticles were fabricated and measured confirming the directional scattering.