title: Mode competition and anomalous cooling in a multimode phonon laser.
abstract: We study mode competition in a multimode "phonon laser" comprised of an optical cavity employing a highly reflective membrane as the output coupler. Mechanical gain is provided by the intracavity radiation pressure, to which many mechanical modes are coupled. We calculate the gain and find that strong oscillation in one mode suppresses the gain in other modes. For sufficiently strong oscillation, the gain of the other modes actually switches sign and becomes damping, a process we call "anomalous cooling." We demonstrate that mode competition leads to single-mode operation and find excellent agreement with our theory, including anomalous cooling.
authors.affiliation: Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA and National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA.
authors.forename: Utku
authors.initials: U
authors.lastname: Kemiktarak
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Durand
authors.affiliation: Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA and National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Metcalfe
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA.
authors.forename: John
authors.initials: J
authors.lastname: Lawall