Variable optical attenuator with a polymer-stabilized dual-frequency liquid crystal.

A transmission-type variable optical attenuator (VOA) based on a polymer-stabilized dual-frequency liquid crystal (PSDFLC) is demonstrated at gamma = 1.55 microm. The VOA is highly transparent in the voltage-off state but scatters light in the voltage-on state. By using a birefringent beam displacer incorporated with half-wave plates, we can obtain a VOA that is polarization independent and that exhibits a 31 dB dynamic range. The polymer networks and dual-frequency effect together reduce the response time (rise + decay) of a 16 microm PSDFLC cell to 30 ms at room temperature and at a voltage of 24 Vrms.