A cascadable polarization-based 1-to-9 multimode optical fiber switch using a PMMA fiber array holder

We have constructed an optical fiber switch, which allows to route an information carrying laser beam to nine multimode optical fibers. The fibers are accurately positioned in a polymethylmethacrylate (PMMA) fiber array holder, fabricated with deep proton lithography. To switch light from one fiber to another, we use active control of the polarization of light by means of nematic liquid crystal retarders or ferroelectric polarization rotators. The system shows insertion losses as low as 3 dB and crosstalk ratios below -30 dB. These figures are still susceptible to considerable improvements. The switching speed is on the order of 10 Hz using nematic liquid crystals and was extended to 10 kHz with ferroelectric liquid crystals. Potential applications of the fiber switch are discussed. As an illustration we have demonstrated the multiplexing of optical fiber proximity sensors. We also describe scale reduction and cascadability issues.