High-sensitivity 25 Gbit/s avalanche photodiode receiver optical sub-assembly for 40 km transmission

A report is presented on an avalanche photodiode receiver optical subassembly module designed for 25 Gbit/s operations at 1310 nm. The receiver optical sub-assembly maintains 3 dB bandwidth as high as 18 GHz for a multiplication factor of up to 10. By 40 km singlemode fibre transmission measurements, receiver sensitivity of 21.7 dBm is demonstrated at a data rate of 25.8 Gbit/s for an input optical signal extinction ratio of 8, with a power penalty of 0.2 dB against the back-to-back condition.