Hexagonal boron nitride cavity optomechanics.

Hexagonal boron nitride (hBN) is an emerging layered material that plays a key role in a variety of two-dimensional devices, and has potential applications in nanophotonics and nanomechanics. Here, we demonstrate the first cavity optomechanical system incorporating hBN. Nanomechanical resonators consisting of hBN beams with dimensions of 13.5 um x 1.1 um x 31 nm were fabricated using electron beam induced etching and positioned in the optical nearfield of silicon microdisk cavities. The resulting cavity optomechanical system has sub-picometer/Hz^0.5 sensitivity to hBN nanobeam motion, allowing observation of thermally driven mechanical resonances with frequencies of 4.6 and 23 MHz, and quality factors of 260 and 1100, respectively, at room temperature in high vacuum. In addition, the role of air damping is studied via pressure dependent measurements. Our results constitute an important step towards realizing integrated optoemechanical circuits employing hBN.