Theory of Operation

Single bubble sonoluminescence (SL) is the spontaneous emission of picosecond pulses of broadband light from a micron-size gas bubble levitated in water by the application of an external sound field.The bubble expands and contracts in phase with the oscillating pressure field.

Much of the recent work on single bubble sonoluminescence has been concerned with the dynamics of the bubble motion and the detailed spectrum in the 200 to 700 nm range using a variety of gas mixtures as the contents of the sonoluminescing bubble. Recent theoretical work with shock wave focusing in the bubble has given peak temperatures up to 10^9 K, while other estimates place the peak temperature in the range of 10^4 to 10^6 K.

The mechanism for the light emission is still not understood. There is general agreement that the violent collapse of a micron size bubble to its hard core limit is at the heart of the light emission process.

The following picture shows the light given off by 2 bubbles trapped in the [1,1,3] mode of a rectangular cell. The frequency at which the light is being emitted is 28.3 kHz.