High bandwidth multimode fiber links using subcarrier muitiplexing in vertical-cavity surface-emitting lasers

Summary form only given. There is currently much interest in low-cost high-speed and short-haul links for local area networks and computer interconnect applications, with standards bodies such as those setting the Gigabit Ethernet standard now considering transmission rates in excess of 1 Gbit/s. Because of cost, particular emphasis has been placed on the use of multimode fiber (MMF) links using vertical-cavity surface-emitting lasers (VCSELs). With increasing data rates however the achievable link lengths become limited due to the modal bandwidth of the MMF. Efforts to overcome this limitation have included the use of wavelength-division multiplexing, multilevel modulation and restricted mode launches. In this paper, however we believe we describe for the first time how subcarrier multiplexing (SCM) techniques can be used to allow link transmission significantly in excess of the specified fiber bandwidth. The technique is robust and has been assessed using a representative range of fibres. A series of 200-Mbit/s channels with carrier frequencies of up to more than twenty times the 3-dB fiber bandwidth have been successfully used, the maximum being limited by the electronics currently available.