Boosting Sonoluminescence
  Single bubble sonoluminescence has been experimentally produced through a novel approach of optimized sound excitation. A driving consisting of a first and second harmonic with selected amplitudes and relative phase results in an increase of light emission compared to sinusoidal driving. We achieved a raise of the maximum photo current of up to 300% with the two-mode sound signal. Numerical simulations of multimode excitation of a single bubble are compared to this result. 
Joachim Holzfuss, Matthias Ruggeberg, and Robert Mettin