Data center industry is facing unprecedented development opportunity; the development of various applications of network gave rise to the vast amounts of data requirements. The artificial intelligence has brought high density calculation. All of the information technology has led to the data center to develop to a higher density, higher bandwidth.
The number of QSFP28 optical transceivers used for optical interconnection in data centers only in 2017 has reached nearly 3 million, and the annual compound growth rate of over 100 percent has continued to increase to 2021, as shown in figure 1:
100G QSFP28 optical transceiver series products for data centers have entered the technology maturity, and rapidly develop in the second half of 2016, among which the fastest growing is the QSFP28 optical transceivers used in the data center interconnection.
Single-wave 100G QSFP28 DR1/FR1 Optical Transceivers Have Become Popular Solutions
At the current market, the optical transceivers based on 4*25G NRZ technology are mainly used for the 100G solution. This technology has a wide range of products in transmission distances: 100m SR4/SWDM4, 300m eSR4, 500m PSM4/CWDM4 Lite, and 2km CLR4/CWDM4. These different types of products create great difficulties for the interconnection, interoperability and compatibility of the Internet, thereby increasing the cost of data centers. Therefore, single-wave 100G optical transceivers are increasingly concerned by Internet companies. According to IEEE regulations, DR1/FR1 is based on the PAM4 modulation format and supports a single-channel 100Gbps (53GBd) class of physical media dependence. DR1 can support single-mode fiber transmission at least 500m; FR1 supports 2km transmission. Compared with the current 100G QSFP28 optical transceivers (4*25Gbps), DR1/FR1 uses only one optical device, which can greatly save the cost of optical transceivers. The DR1/FR1 optical transceivers based on the QSFP28 package can be completely compatible with the existing 100G switch.
Single-wave 100G Optical Transceivers Will Be the Best Solution for the Next Generation of Data Center
From the product application level, 100G QSFP28 DR1/FR1 optical transceiver can be considered as the solution for the next-generation 100G QSFP28 optical transceivers, and they can cover the transmission distance of the vast majority of data center optical interconnections. And it is expected to replace all current QSFP28 optical transceiver solutions within 500m, which effectively avoids the problem of 100G optical transceiver solution selection and interconnection. Another important application of DR1 is that it can be used for fan-out connection with DR4, between the top switch and the server. From the perspective of the evolution of technology R&D, DR1/FR1 can be used as the basis for research on LR1 (electrical solutions are almost the same), and it can also accumulate corresponding data for the development of DR4/FR4 (optoelectronic solutions are all the same, only the expansion of channels).
From the technical level, 100G QSFP28 DR1/FR1 technology uses the PAM4 modulation technology, which greatly improves the signal rate and can effectively reduce the number of signal channels compared to the NRZ modulation technology. The PAM4 modulation technology replaces the existing NRZ modulation technology in the next-generation 400G optical transceiver products, reducing the size of the optical transceivers and reducing power consumption, thereby reducing the cost of the optical transceivers.