Abstract: A new technique for sensing optical cavity mode mismatch using a mode converter formed from a cylindrical lens mode converting telescope, radio frequency quadrant photodiodes (RFQPDs), and a heterodyne detection scheme. The telescope allows the conversion of the Laguerre-Gauss basis to the Hermite-Gauss (HG) basis, which can be measured with quadrant photodiodes. Conversion to the HG basis is performed optically, measurement of mode mismatched signals is performed with the RFQPDs, and a feedback error signal is obtained with heterodyne detection.

Abstract: A new technique for sensing optical cavity mode mismatch using a mode converter formed from a cylindrical lens mode converting telescope, radio frequency quadrant photodiodes (RFQPDs), and a heterodyne detection scheme. The telescope allows the conversion of the Laguerre-Gauss basis to the Hermite-Gauss (HG) basis, which can be measured with quadrant photodiodes. Conversion to the HG basis is performed optically, measurement of mode mismatched signals is performed with the RFQPDs, and a feedback error signal is obtained with heterodyne detection.

Abstract: A stable single-carrier optical spring, comprising a pair of dielectric mirrors, each having a dielectric coating, and positioned to form a standing wave from an incident optic field. The dielectric coating has a plurality of layers, where at least the first layer is sized to be an odd multiple of half a wavelength of the laser beam, to feature an opposite-sign photo-thermal effect due to the detailed interaction of the optical field with the coating. This results in an opposite-sign photo-thermal effect at the optical spring frequency. The dampening effect is large enough to stabilize the radiation pressure based optical spring, resulting in a statically and dynamically stable optical spring. As a result this coating allows stable locking of a cavity with a single laser frequency using radiation pressure feedback.

Abstract: A stable single-carrier optical spring, comprising a pair of dielectric mirrors, each having a dielectric coating, and positioned to form a standing wave from an incident optic field. The dielectric coating has a plurality of layers, where at least the first layer is sized to be an odd multiple of half a wavelength of the laser beam, to feature an opposite-sign photo-thermal effect due to the detailed interaction of the optical field with the coating. This results in an opposite-sign photo-thermal effect at the optical spring frequency. The dampening effect is large enough to stabilize the radiation pressure based optical spring, resulting in a statically and dynamically stable optical spring. As a result this coating allows stable locking of a cavity with a single laser frequency using radiation pressure feedback.