Transitions from conservative to non-conservative regimes in optical binding of colloidal matter.

We study light generated inter-particle interactions known as optical binding. These forces are mediated by the particle light scattering making it uniquely responsive to simple changes in the parameter space. For instance, we find that many colloidal particles placed in a weakly focused laser beam can self-assemble into higher-order and multi-leveled structures which can be tuned with simple alterations. We share experimental results which conclude a dramatic change in assembly patterns by changing particle index of refraction; namely, a switch between a conservative pair-wise regime to highly non-conservative many-body regime.