Photochromic Molecules Enable Optical Control of Optomechanical Coupling in a Cavity

Expanding the control of optomechanical coupling into the optical domain, namely beyond electronic and electromechanical gates, offers unequalled advantages in terms of spatial precision and remote operation. Here, a photochromic-based system is introduced with optically tunable optomechanical coupling. The system features a multilayered membrane as one of its mirrors, as well as a polymer layer doped with a photochromic molecule and a near-infrared absorbing dye. The interaction between mechanical modes and the electromagnetic field is harnessed to lower the effective temperature of mechanical vibrations. Laser cooling of a membrane vibrational mode is evidenced to about 115 K, and it is found that the cooling efficiency, mechanical damping, and photothermal response time can be effectively tuned by isomerization of the photochromic component. Such effect leads up to about 60% increase in cooling efficiency, related to photoinduced changes in volume and thermal properties during isomer conversion. These findings introduce new possibilities for the development of optomechanical systems with tunable properties entirely driven by light for applications in advanced sensing, nanomechanics, and optical logics.