Polarization control using nematic liquid crystals

A new type of nematic liquid crystal (NLC) based polarization independent 1×2 optical switch is demonstrated. Experiments show that this system is capable of converting any arbitrary input polarization into a horizontal or vertical output of high polarization extinction ratio (>26 dB). Moreover, a basic polarization independent alignment tolerant 1×2 optical switch is proposed and demonstrated, comprising a NLC-based polarization controller in cascade with half wave plates. Experiments show that this system is capable of realizing a high switch contrast (>27 dB), nearly independent of the input polarization. The measured polarization extinction ratio of the output light was about 40 dB. Our NLC-based polarization control provides low driving voltages (<5V), no moving parts, high performance and possible low insertion loss.