Oclaro 400-Gbps lithium niobate modulator hits sampling stage

Optical components and subsystems vendor Oclaro, Inc. (NASDAQ: OCLR) says it has begun delivering early samples of a 400-Gbps lithium niobate (LiNbO3) external modulator. The modulator is designed to support single-carrier or -wavelength 400G transmission via 16QAM.

The polarization-multiplexed quad parallel Mach-Zehnder (PM-QMZ) modulator integrates an input beam splitter, four parallel Mach-Zehnder modulators configured for I-Q modulation, a polarization combiner, and monitor photodiodes for power and bias control in its hermetic package. It offers 3-dB bandwidth exceeding 35 GHz, what the company describes as "very smooth" optical response up to 50 GHz to support symbol rates up to 64 Gbaud, extinction ratio above 25 dB, and insertion loss below 13 dB.

The company is the first to reach sampling with an optical modulator capable of supporting single-channel 400G, said Robert Blum, product marketing director at Oclaro. He believes it likely the company also will be first to market with a commercial product once the modulator is ready for production. That event is gated somewhat by the Optical Internetworking Forum's (OIF's) work on packaging specifications. However, Blum expects the modulator to be commercially available by the end of 2016. Such timing will be in synch with expected 400G roll outs, he believes.

Noting the popularity of 8QAM offerings among system houses that would support 150 Gbps per channel and 300 Gbps in a two carrier/wavelength configuration (see, for example, "Flexi-rate optical interfaces go mainstream"), Blum said the modulator would work fine in such applications.

The modulator's development validates continued work in LiNbO3, Blum said, despite the fact that indium phosphide (InP) has become the modulator platform of choice at speeds such as 100G. Blum acknowledged that a 400G InP modulator will come eventually. "But that will take several years to come to market. By that time we'll be on to terabit networks," he predicted.

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