A silicon mechanical-photonic wavelength converter, not based on absorption, has been recently proposed to address the need for all-silicon photodetectors in the infrared spectrum. Its implementation requires high-frequency modulation, from hundreds of kHz to 1 MHz, of a light beam over an area of a few hundred microns. Since the displacement amplitudes of tens of microns at these frequencies are unfeasible, a moving grate is proposed to locally modulate the light. The MEMS actuator, an array of 1 µm-wide 1 µm-spaced beams (100 × 100 µm2 area), achieved displacements of 70 nm at atmospheric pressure and 350 nm under low vacuum, with 10 Vpp actuation at 290 kHz (FOM displacement × frequency2 above previously reported works).