It is cost-effective to install multiple fibers in each link of an all-optical network, because the cost of fibers is relatively low compared with the installation cost. In this paper we propose an architecture of an bufferless multifiber Optical Packet Switch (OPS) using the wavelength dimension for contention resolution. In order to save the number of Tunable Optical Wavelength Converters (TOWC), the proposed architecture shares the TOWCs among the arriving packets. An analytical model, validated by means of simulations, is proposed to evaluate the Packet Loss Probability of the switch. A sensitivity analysis of the TOWCs saving of a multi-fiber switch with respect to a single-fiber switch is carried out as a function of the main switch and the traffic parameters (number of input lines, number of wavelengths per fiber, offered traffic,……). In some cases the saving can reach 50%.