Optical local area networks (LANs) using wavelength selective couplers

In wavelength-division-multiplexed ring and bus networks, stations normally connect to the fiber using fused biconical taper (FBT) attachments. In this paper, we investigate protocols for multichannel photonic bus/ring LANs which use active wavelength-selective taps rather than passive ones. Since stations actively tap the channel that they are accessing, synchronization and other functions are identical to existing single-channel LANs. However, in order to avoid "re-tuning collisions", the media access protocols in these designs must ensure that stations do not re-tune their couplers at inappropriate times. This constraint places restrictions on the physical parameters over which system performance is efficient. In particular, we find that these designs may be efficient in the local area but lack the scalability required for metropolitan coverage. In this paper, capacity and delay models are also derived, and comparisons are made with conventional passive networks.