In a multiwavelength optical network with tunable transceivers, an algorithm to make the transmitter and the receiver tuned to the same wavelength simultaneously is needed. This paper proposes contention-based reservation protocols using a separate control channel for multiwavelength optical networks with a passive star topology, First, we present a protocol which can be used in the network where the ratio of the end-to-end signal propagation delay to the transmission time of a data packet is smaller than 1. Also, for a very high speed network where this ratio is greater than 1, we present three protocols according to the variability of the packet length and the buffering of the reservation. To access the control channel, all the proposed protocols use the slotted ALOHA protocol. We analyze these protocols with a finite population model and investigate the delay-throughput characteristics.