In this work we show that two absorbing microbeads can briefly share the same optical trap while creating microscopic explosions. Optical forces pull the particles towards the waist of the trapping beam, once a particle reaches the vicinity of the waist, the surrounding liquid is superheated creating an explosion or cavitation bubble that pushes the particle away while lengthening or shortening the trajectories of the surrounding particles. Hence effectively coupling all the trajectories to each cavitation event. We find that when two microbeads reach the waist simultaneously within a distance of 2.9 µm from the beam center in the transverse plane, a larger explosion might result in ejection from the trap. The measured maximum radial displacements ∆ρc due to cavitation are ∆ρc = 3.9 ± 2.2 µm when the particles reach simultaneously with maximum bubble sizes Rmax = 6.2 ± 3.1 µm, while for individual cases when one of the particles is outside 2.9 µm prior to cavitation ∆ρc is 2.7 ± 1.2 µm and Rmax = 4.2 ± 1.6 µm. We also measure the characteristic timescale of two particle coalescence which is a measure of the expected time that the particles can stay trapped near the waist. The measurements are fitted by a Poisson decaying exponential probability distribution.A simple one dimensional model shows that the characteristic timescales for transient trapping of multiple absorbing particles decrease as more objects are added.

Microscopic vapor explosions or cavitation bubbles can be generated periodically in an optical tweezer with a microparticle that partially absorbs at the trapping laser wavelength. In this work we measure the size distribution and the production rate of cavitation bubbles for microparticles with a diameter of 3 µm using high speed video recording and a fast photodiode. We find that there is a lower bound for the maximum bubble radius Rmax ∼ 2 µm which can be explained in terms of the microparticle size. More than 94% of the measured Rmax are in the range between 2 and 6 µm, while the same percentage of the measured individual frequencies fi or production rates are between 10 and 200 Hz. The photodiode signal yields an upper bound for the lifetime of the bubbles, which is at most twice the value predicted by the Rayleigh equation. We also report empirical relations between Rmax, fi and the bubble lifetimes.

Microscopic vapor explosions or cavitation bubbles can be generated periodically in an optical tweezer with a microparticle that partially absorbs at the trapping laser wavelength. In this work we measure the size distribution and the production rate of cavitation bubbles for microparticles with a diameter of 3 µm using high speed video recording and a fast photodiode. We find that there is a lower bound for the maximum bubble radius Rmax ∼ 2 µm which can be explained in terms of the microparticle size. More than 94% of the measured Rmax are in the range between 2 and 6 µm, while the same percentage of the measured individual frequencies fi or production rates are between 10 and 200 Hz. The photodiode signal yields an upper bound for the lifetime of the bubbles, which is at most twice the value predicted by the Rayleigh equation. We also report empirical relations between Rmax, fi and the bubble lifetimes.