Addressing a serious gap in capabilities, NTT Electronics (NEL) has announced at ECOC 2015 in Valencia, Spain that it has begun sampling a digital signal processor (DSP) for coherent transmission applications that can support 200-Gbps data rates. The NLD0660 DSP leverages 20-nm CMOS mixed-signal expertise from Broadcom Corp. (NASDAQ: BRCM; see "NTT Electronics, Broadcom pair for coherent DSP").
Meanwhile, the company is nearing sampling of a DSP for 400-Gbps requirements as well.
NEL dominated the first wave of coherent optical transponders, which were based on a multisource agreement (MSA) from the Optical Internetworking Forum (OIF). However, it initially miscalculated market requirements for pluggable optical transceivers for coherent applications, specifically the CFP2 Analog Coherent Optics (ACO) module. While the NEL DSP for such optical modules met performance and power requirements for 100-Gbps operation, competitor ClariPhy Communications trumped NEL's play by offering a DSP that also supported 200-Gbps requirements (see "ClariPhy LightSpeed-II coherent SoCs for 100G, 200G, 400G near sampling" and "ClariPhy 200G coherent DSP chip reaches production").
NEL has now caught up to ClariPhy in terms of 200G support with the NLD0660. The DSP accommodates 16QAM and 8QAM (the latter for 150-Gbps optical transmission; two devices may be paired to support 300-Gbps requirements) as well as DP-QPSK. It also offers improved optical signal-to-noise ratio (OSNR) compared to the earlier DSP via soft-decision forward error correction (SD-FEC) that achieves 12-dB net coding gain (NCG).
An NEL source at ECOC said the company is well along on a DSP for 400-Gbps coherent transmission applicatinos as well. That device should begin sampling by the end of this year, with general availability targeted for the first half of 2016.
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