Switchable Fresnel zone lenses for optical interconnections

Various on-axis and off-axis Fresnel zone lenses with different focal lengths and of different apertures were fabricated in quartz glass by means of microstructuring techniques. The kinoform profile of the diffractive optical elements was approximated by a staircase-like profile having a number of discrete phase levels. Dynamic, that is electrically switchable, lenses have been realized by filling the structured surface with liquid crystal. By applying an AC-voltage the elements can be switched from the state of a `focusing lens' to that of a `transparent glass- plate'. The optical properties of the lenses as well as the switching behavior were studied. Experimental measurements will be compared with theoretical results.