300m transmission on legacy multimode fibre

Finisar Corporation has demonstrated a 10Gb/sec XFP optical transceiver operating on 300 meters of legacy multimode fibre.

Finisar’s new XFP optical module uses an uncooled 1310nm laser and Electronic Dispersion Compensation (EDC) technology to transmit 10Gb/sec error-free over up to 300 metres of virtually any grade of legacy multimode fibre.

This includes the 160/500MHz·km grade 62.5/125um fibre that constitutes the vast majority of the current infrastructure in the Enterprise LAN environment.

The company claims that other 10Gb/sec transceivers and transponders that use 850nm lasers can only transmit 26 metres on the most common legacy fibre. It says that in order for them to reach 300 meters, end-users need to deploy new high-bandwidth multimode fibre (2000MHz·km) at significant expense.

Another solution called LX4 uses four separate lasers of different wavelengths to achieve 300 metres, which translates into higher power dissipation, higher costs and reduced reliability.

‘We believe that EDC technology provides the most practical solution for transmitting 10Gb/sec over 300 meters of legacy multimode fibre,’ said Lew Aronson, Chief Scientist at Finisar.

Finisar has been shipping 10km versions of XFP transceivers for several months, and has already demonstrated a 40km DWDM XFP version at recent trade shows.

The XFP is an 10Gb/s optical transceiver module standardised by the <a href=’http://www.xfpmsa.org’>XFP MSA Group</a>), which currently has more than 75 member companies.

XFP transceivers support digital diagnostics functions via a 2-pin serial bus. They provide calibrated, real-time measurements of the laser bias current, transmitted optical power, received optical power, internal transceiver temperature and supply voltage.

This diagnostic functionality allows telecommunication and data communications companies to implement reliable performance monitoring of their optical links.

Additionally, Finisar’s hot-pluggable XFP transceivers include a ‘bail’ latch release mechanism for insertion and removal into the standardised metallic cage. This cage is press-fit on the host board and includes a new modular heat-sink design to facilitate heat management.

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