In booth 162 at the European Conference on Optical Communications (ECOC 2017) in Gothenburg, Sweden (18-20 September), Source Photonics Inc of West Hills, CA, USA (which provides broadband access optical components and modules) and Credo Semiconductor of Milpitas, CA, USA – which provides serializer-deserializer (SerDes) mixed-signal semiconductor technology for data-center, enterprise networking and high-performance computing applications – is demonstrating single-lambda 100Gb/s connectivity over 20km of fiber using a compact TOSA (transmitter optical sub-assembly) and ROSA (receiver optical sub-assembly) capable of 53Gbaud PAM4 operation.
Increasing demand for more bandwidth in Cloud data centers is creating the need for more efficient and higher-throughput optical transceivers beyond the currently deployed 100G 4x25G WDM technology, says Source Photonics. The next-generation transceivers will need to support higher-order modulation techniques such as PAM4 (4-level pulse amplitude modulation) and higher-data-rate operation at 53Gbaud. Implementations that can be supported with this technology include 400G-DR4/FR4 in addition to 100G-DR/FR/LR.
The demonstration consists of Source Photonics internally packaged TOSA and ROSA sub-assemblies in an optical loopback configuration through 20km of single-mode fiber (SMF) using a single 100G channel of Credo’s low-power PAM4 IC technology. The bit-error-rate (BER) after 20km of fiber remained better than the KP4 FEC (forward error correction) requirement and was around 5×10-5. The TOSA is based on Source Photonics’ externally modulated laser (EML) technology, which provides the necessary bandwidth to achieve a TDECQ (transmitter dispersion eye closure quaternary) value below 2.5dB. The room-temperature link budget of 10dB provides considerable margin for the most significant link specifications under development in the industry, allowing production margin for performance variations. The results show that the building blocks necessary to realize 53Gbaud single-lambda operation are available and ready to serve the needs of next-generation data-center deployments.
The demonstration achieves with one laser and one receiver what currently requires four lasers and four receivers – facilitating not only lower-cost future 100G but also accelerating the development of 400G products, it is reckoned.
“We are continuing to invest in next-generation technology, such as single-lambda 100G, as part of our commitment to providing leading-edge solutions for data centers,” says Manish Mehta, Source Photonics’ executive VP, product line management.
“The hyper-scale Cloud providers have spoken and 100G per lambda solutions are a key connectivity priority,” says Rajan Pai, Credo’s VP of system applications. “Our unique SerDes architecture allows us to deliver single-lane 100G performance at the lowest power, which will enable the volume deployments of 100G and 400G optical modules.”
