Detuning-symmetric laser cooling of many mechanical modes with a photothermally modified cavity

We simultaneously cool $\gtrsim$100 mechanical modes of a membrane with a photothermally modified optical cavity driven by a single blue-detuned laser. In contrast to radiation pressure and bolometric forces applied directly to the mechanical system, this cooling effect does not depend on the sign of detuning, allowing for single-laser stabilization (i.e., simultaneous positive optical spring and damping) that is especially effective at room temperature and high laser power. We also provide intuition about the competing thermal processes, and propose two simple modifications to the mirror coatings that can strongly enhance this effect.