u²t Photonics has announced a balanced detector that operates at 70GHz. Such a bandwidth supports 64Gbaud symbol rates, twice that of current 100G coherent optical transmission systems.
The German company announced a coherent photodetector capable of 64Gbaud in 2012 but that had an operating bandwidth of 40GHz. The latest product uses two 70GHz photodetectors and modified packaging to meet the higher bandwidth requirements.
“The achieved performance is a result of R&D work using our experience with 100GHz single photodetectors and balanced detector technology at a lower speed,” said Jens Fiedler, executive vice president, sales and marketing, at u²t Photonics.
The markets for the device are test and measurement systems and research and development (R&D). “It will enable engineers to work on higher-speed interface rates for system development,” said Fiedler.
The balanced detector could be used in next-generation transmission systems operating at 64Gbaud, doubling the current 100Gbps data rate while using the same dual-polarisation, quadrature phase-shift keying (DP-QPSK) modulation scheme.
A 64Gbaud DP-QPSK coherent system would halve the number of superchannels needed for 400Gbps and 1Tbps transmissions. In turn, using 16-QAM instead of QPSK would further halve the channel count – a single dual-polarisation, 16-QAM at 64Gbaud would deliver 400Gbps, while three channels would deliver 1.2Tbps.
However, for such a system to be deployed commercially the remaining components – the modulator, device drivers and the DSP-ASIC – would need to be able to operate at twice the 32Gbaud rate; something that is still several years out. Fiedler points out, however, that the industry is also investigating baud rates between 32G and 64G.
The monolithically integrated balanced detector has been sampling since March.
By Roy Rubenstein
Press release: u²t Photonics unveils the world’s fastest balanced photodetector with 70GHz 3dB bandwidth