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 lambda=1.55 (mu)m. 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 halfwave 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 (mu)m PSDFLC cell to 30 ms at room temperature and at a voltage of 24 V_rms.