Ultrahigh continuous-wave intensities $(>300\mathrm{GW}/{\mathrm{cm}}^2)$ in high-numerical-aperture optical cavities enable applications from phase-contrast electron microscopy to ultradeep dipole traps for molecules. However, the intensity can be limited by the optomechanical parametric instability (PI), where mirror vibrations scatter light from one cavity mode into another. We observe parametric instability in a tabletop Fabry-Pérot cavity, show that the mechanical modes are MHz-frequency bulk acoustic modes inside the mirrors, and measure their $Q$ factor. By using low-$Q$ mirrors, we achieve $>500\mathrm{GW}/{\mathrm{cm}}^2$ intensities in an open, free-space cavity.

Close

PrevNext

View figure in article

• Cold and ultracold molecules
• Nonlinear optics
• Optical lattices & traps
• Optomechanics
• Cavity methods
• Cavity resonators