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Single-wave optical modules are coming, the new choice for 100G data center interconnection

June 2, 2023

Carrier-grade single-wave 100G QSFP28 LR1 and 100G QSFP28 ER1 optical modules offer new options for long-haul interconnects in 100G data centers.

The mainstream solution used in 100G data centers has been the 4x25G NRZ technology, which consists of four sets of transmitters and receivers. In order to save fiber resources for long-distance transmission needs, WDM technology is usually used to multiplex the four optical signals onto a single fiber for transmission.

However, with the development of PAM4 technology, single-wave 100G solutions have matured, and 100G single-wave LR1 and ER1 have been able to replace LR4 and ER4 Lite as a more cost-effective option for 100G long-distance transmission.

100G QSFP28 optical module market demand forecast
Figure 1: 100G QSFP28 optical module market demand forecast

The 100G single-wave optical module uses 100G PAM4 modulation to reduce optical complexity and cost by reducing the number of optical transmitters and receivers from four to one. Compared to traditional 4x25G LR4 and ER4 Lite solutions, the single-wave 100G LR1/ER1 offers the following advantages.

Only one optical chip is used at the transmitter and one at the receiver, resulting in a simpler product design, lower device costs, and lower production and manufacturing costs.

The use of a cleaner traditional TO hermetic package results in fewer production man-hours and lower manufacturing costs.

It can directly interconnect with 400G modules of 4x100G PAM4, further enhancing the capacity of the link and the flexibility of networking.

However, the 4x25G solution also has its non-negligible advantages. The 4x25G solution uses NRZ modulation, which is a more mature technology, and the cost of a single device is lower. The current power consumption of 100G LR1/EM1 is still slightly higher than that of 100G LR4/ER4 Lite. And 4x25G 100G optical module can be directly interconnected with 25G optical module, 25G/100G data center is still the mainstream at present.

100G QSFP28LR1/ER1 Solution

Data Center

● Switch-to-switch connectivity

● Data center to data center connectivity

● Connection to 400G port

Data Center

Service Provider Network

● Incremental upgrade to 400G hardware

● Maximum use of 400G port bandwidth

● Future-proof QSFP28 hardware

Service Provider Network

Single-wave 100G technology allows service providers and network operators to upgrade sites individually

● Upgrade one site at a time

● Connecting new 400G sites via 4x100G branch cables

● Leverage your 400G port bandwidth with 4x100G branch cables

● Reuse of 100G optics in new 400G ports

100G single-wave not only provides a lower cost 100G-link, but also reduces the complexity of optical components. According to IEEE experts, carrying 100GE optical signals over a single optical channel can reduce fiber deployments and help save up to 40% in deployment costs. 100G single-wave simplifies the structure of 400G modules, making the transition from 100G to 400G easier.