Phase behaviour of colloids in confining geometry

We review recent experimental and theoretical studies on two-dimensional (2 D) melting in the presence of a one-dimensional (1D) periodic potential. It is demonstrated that a colloidal suspension which is exposed to the interf erence pattern of two overlapping laser beams show a phase behaviour being totally different from that of 2D systems on homogeneous substrates. This i s attributed to the role of particle fluctuations which in the presence of sufficiently strong periodic external potentials enhance particle interacti ons and thus promote crystallization.