Holographic perfect shuffle permutation element for a miniaturized switching network

Abstract

A holographic perfect shuffle element with 80 channels for a miniaturized switching network is reported. An array of vertical-cavity, surface-emitting lasers is used as a transmitter. The whole permutation is carried out totally in glass. The 80 channels are permuted within a rectangle with a volume of 3 mm × 4 mm × 2 mm. Four planes of stacked volume holograms recorded in dichromated gelatin form this perfect shuffle element with an angular spectrum between 7° and 35°. Changes in the wavelength of the diode lasers to Δλ = ±10 nm can be compensated with this setup. The overall efficiency per channel lies between 40% and 60%. When Fresnel reflections and absorption are taken into account, a transmission per hologram between 78% and 90% is achieved.