We have experimentally demonstrated a 5-Tb/s ATM (asynchronous transfer mode) switching system called OPTIMA-2 (Optically interconnected multi-stage ATM switch architecture) that uses optical packet-by-packet switched WDM (wavelength division multiplexing) links for the intra-switch interconnection. In this paper, we describe the design, fabrication, and evaluation of the optical WDM interconnection modules developed for it.