Opto-mechanics with sub-wavelength grating-membranes*

We fabricate highly reflective sub-wavelength grating membranes using stoichiometric silicon nitride. We achieve a grating reflectivity of 99.6\% with a membrane mechanical frequency of $\sim$1 MHz. We integrate the grating-membrane into a Fabry-Perot cavity and investigate its opto-mechanical properties. We also consider the prospect of using them for three mode opto-mechanics experiments where the two optical cavity modes are coupled through a mechanical mode.