In this letter, we propose and experimentally demonstrate a novel all-optical two-dimensional time-wavelength optical code-division multiple access (OCDMA) code-drop unit for transparent ring networks. The ultrafast all-optical code-drop unit is based on the terahertz optical asymmetric demultiplexer.We have demonstrated experimentally the capability to drop the correlated code at the desired node in a four-user ring network operating at 253 Gchips/s with a single-user bit rate of 2.5 Gb/s. Error-free operation is obtained. Dropping codes from multihop networks facilitates the development of optical add–drop multiplexers for OCDMA network
