A variable optical attenuator (VOA) based on the internal reflection effect is proposed. This simple configuration makes use of an enlongated prism with SiO 2 thin film on both underside of it to realize polarization insensitivity and large range of dynamic attenuation. As a result, a sample VOA was obtained with an attenuation range above 20 dB and polarization dependent loss below 0.5 dB experimentally.