A network device used by telecom carriers to switch high-speed optical signals (OC-3, OC-12, OC-48, etc.). It differs from a digital cross-connect in that it deals with multiple high-speed signals that are switched in their entirety and not multiplexed together. Also known as "OXCs," optical cross-connects work entirely at the optical layer and may be able to operate without having to convert to electrical and back again. Tellium, Inc., a Bellcore spin-off acquired by Zhone Technologies (www.zhone.com) in 2003, introduced the first optical cross-connect in 1998. See digital cross-connect.