The attenuator for the wavelength at 1550 nm is fabricated by using the capillary effect to infiltrate liquid crystal (LC) E7 into hollow waveguides (HWGs) on silicon substrate with SiO2 cladding layer. The length of the waveguide is 0.4 cm. The device can be operated with relatively low driving voltage below 5 Vpp with the distance between two electrodes to be 9 μm. The light attenuation of the device can be over 30 dB. The performance of the device is independent of the polarization states of the input light.