Abstract: A novel variable optical attenuator （VOA）based on SOI material is designed and fabricated.The modulation area is formed of a special transverse PIN junction on a double-rib waveguide,which can enhance the overlap between the electric field and the optical field, and increase the injectionefficiency. The VOA can achieve up to 20dB attenuation with the highest power consumption of 650mW. The on-chip insert loss of the VOA is 3.6dB.