News and Reviews (May 2014)

Simple transmission phase gratings make colour filters in the visible

Current research of a Nanoscribe customer

(Piotr Wasylczyk) Optical transmission color filters can generally be realized using absorption, interference or diffraction. In a series of experiments based on this last approach, researchers from Photonic Nanostructure Facility (PNaF), led by Piotr Wasylczyk, at the Faculty of Physics, University of Warsaw, fabricated and characterized diffraction structures in the form of a regular grid of pillars.

Such “forest of columns” as it has been nicknamed, can generate a significant range of hues in white light transmission due to colour-dependent diffraction. By designing the structure topography, the wavelength-dependent diffraction efficiency can be tuned, resulting in the desired light transmission profiles. Red, green and blue filters have been demonstrated and the experimental results compared with numerical simulations of light propagation in the dielectric microstructures.
The simple phase diffraction gratings offer several advantages compared to other light filtering technologies: not only can they be mass-produced using replication, but also high resolution spatial patterning can be achieved as well as straightforward integration into micro-optical devices.

This research has been supported by National Science Center (Poland) within the DEC-2012/05/E/ST3/03281 grant funds and by ERDF within the

Publication Source: Optics Express, 21, 31919 (2013).

color filterscolor filters







left: SEM image of the pillar grating. More than thousand of 1.5 micron high polymer micro-pillars cover the
38 x 38 μm2 area.
right: Computer graphic based on a white light microscope showing a range of colours available for the
pillartype gratings.