title: Optimizing pump threshold and conversion efficiency of whispering gallery optical parametric oscillators by controlled coupling.
abstract: Threshold and efficiency of optical parametric oscillation in whispering gallery resonators have been predicted to depend strongly on the coupling strength. Our experiments, varying the coupling strength continuously over 3 orders of magnitude, confirm these predictions. The pump threshold changes by a factor of 20, allowing the adaptation of the system to a wide range of input powers. The minimum threshold of 0.20 mW occurs for significant pump undercoupling. The efficiency increases monotonically with coupling, spanning 4 orders of magnitude with a maximum efficiency of 30% in contact yielding output powers exceeding 1 mW.
authors.affiliation: Laboratory for Optical Systems, Department of Microsystems Engineering—IMTEK, University of Freiburg, Georges-Koehler-Allee 102, Freiburg 79110, Germany. tobias.beckmann@imtek.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Beckmann
authors.forename: Karsten
authors.initials: K
authors.lastname: Buse
authors.forename: Ingo
authors.initials: I
authors.lastname: Breunig