Optically Defined Phononic Crystal Defect

We demonstrate a mechanical crystal with an optically programmable defect mode. By applying an optical spring to a single unit cell of a phononic crystal membrane, we smoothly transfer a single mechanical mode into the band gap, thereby localizing its spatial profile from one spanning the entire crystal to one confined within a few unit cells. This localization is evidenced by an enhanced mechanical frequency shift commensurate with a 37-fold reduction in the mode's participating mass. This fast, reversible, all-optical control represents a qualitatively new way to engineer mechanical defects, advantageously with in situ reconfigurability. locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon Physics Subject Headings (PhySH)DefectsOptomechanicsPhononic crystalsCavity resonatorsCoherent controlOptical lattices & trapsOptical techniques