| A single air bubble in degassed ultrapure water was acoustically levitated in a cylindrical resonator and made to sonoluminescence. A Nd:YAG nanosecond laser was fired synchronously and focused onto the bubble at the moment when the bubble was emitting photons. The laser enhancement on single bubble sonoluminescence was investigated by detecting the change in the brightness of the sonoluminescence when the laser was on and off. Laser induced background signal overshadows the sonoluminescence signal at strong laser power, possibly from the Raman effect or the plasma formation. At a low laser power of 1.7 mJ per pulse, a 5--9% increase in sonoluminescence intensity was found, while the relative standard deviation in the amplitudes of sonoluminescence pulses was found to be about 45%. Therefore, a definitive answer to the question of the laser enhancement of sonoluminescence cannot be given. |
