8 X 8 holographic single-mode fiber switch based on electrically addressed nematic liquid crystal deflectors

We present the design and the system characterization of a 8 X 8 free-space optical switching matrix based on the cascade on two 1D deflectors. These devices are based on phase ramps generated into parallel aligned nematic liquid crystal cells. Each cell is divided into 8 arrays with 309 2.5 micrometers -wide electrodes. Each of these arrays is addressed by Tape Automatic Bounded circuits which are reported onto the transparent Indium Tin Oxide on glass substrate. A specific software allows to determine the supply voltages required to establish a given set of interconnections. The two liquid crystal cells, which have been optimized to operate in the 1.55 micrometers window, have an efficiency higher than 70% for deflection angles up to 2.5 degree(s). These cells have been associated with single mode fiber and diffractive lens arrays into a rack-mounted demonstrator, which include the required optics to achieve polarization diversity. The average insertion loss is 9.0 dB with a maximum of 12.5 dB; the polarization dependent loss is lower than 1 dB, and worst case isolation is about 30 dB.