Quantum dot amplifier restores 40Gb/s signals
Japanese researchers claim to have developed the first quantum-dot device capable of restoring optical signals to their original quality without electronic conversion.
The Fujitsu Laboratories team that developed the quantum dot semiconductor optical amplifier (SOA) will detail the technology at this week's Optical Fiber Communication (OFC) conference.
As well as re-amplifying a degraded 1550 nm optical signal, the SOA also suppresses noise (known as re-shaping) and reduces timing jitter (known as re-timing).
Optical signals in current networks are usually restored only after being converted into electronic signals. Fujitsu's SOA, which was developed under a Japanese government-funded project, promises to shrink optical regenerators in future networks.
According to the company, using an improved InAs quantum-dot structure based on an InP substrate accelerated the gain saturation response time of the SOA by a factor of 1000.
This improvement in response time means that the waveform is not degraded to such a large extent as normal during optical regeneration.
Fujitsu admitted that further development of the device is needed, however. For example, fluctuations seen during the off-cycle of the signal still need to be reduced.
As a result, commercial deployment of the technology is still a long way out, with Fujitsu believing that the SOA will only become a practical technology around 2010.