Suppression of classic and quantum radiation pressure noise by electro-optic feedback

We present theoretical results that demonstrate a new technique that can be used to improve the sensitivity of thermal noise measurements: intracavity intensity stabilization. It is demonstrated that electro-optic feedback ca n be used to reduce intracavity intensity fluctuations, and the consequent radiation pressure fluctuations, by a factor of 2 below the quantum-noise l imit. We show that this reduction is achievable in the presence of large cl assic intensity fluctuations in the incident laser beam. The benefits of th is scheme are a consequence of the sub-Poissonian intensity statistics of t he field inside a feedback loop and the quantum nondemolition nature of rad iation pressure noise as a readout system for the intracavity intensity flu ctuations. (C) 1999 Optical Society of America. OCIS codes: 270.2500, 120.5 050, 120.7280.