Optical cooling of a micromirror of wavelength size

The authors report on the passive optical cooling of the Brownian motion of a cantilever suspended micromirror. They show that laser cooling is possible for a mirror of size in the range of the diffraction limit (at λ=1.3μm). This represents the tiniest mirror optically cooled so far, with a mass of 11.3pg, more than four orders of magnitude lighter than current mirrors used in cavity cooling. The reciprocal effect of cooling is also investigated and opens the way to the optical excitation of megahertz vibrational modes under continuous wave laser illumination.