A novel design and fabrication approach for a high fill-factor micro-electro-mechanical system （MEMS） micromirror array-based wavelength-selective switch （WSS） is presented. The WSS is composed of a polarization-independent transmission grating and a high fill-factor micromirror array. The WSS is successfully demonstrated based on the fabricated high fill-factor micromirror array. Test results show that the polarization-dependent loss （PDL） is less than 0.3 dB and that the insertion loss （IL） of the wavelength channel is about -6 dB. The switching function between the two output ports of WSS is measured. The forward switching time is recorded to be about 0.5 ms, whereas the backward switching time is about 7 ms.
