2018-03-02

The Latest QSFP28 Optical Transceivers: QSFP28 4WDM and QSFP28 ER4 Lite


The 100G optical module is with a variety of packaging forms, mainly including the early CFP/CFP2/CFP4 and the new-generation QSFP28. As a hot solution of 100G network, CFP series and QSFP28 optical transceiver have their own advantages. They all play a role in the specific application of 100G network. Currently, it seems that QSFP28 series optical transceiver is in greater favor than CFP series opticcal module transceiver. With respect to QSFP28 series optical module, there are two new types: 100G QSFP28 ER4 Lite optical transceiver module and 100G QSFP28 4WDM optical transceiver module. Then Gigalight will have an introduction to them in this article.
An Introduction to QSFP28 4WDM Optical Transceiver
4WDM(4-Wavelength Wavelength Division Multiplexing) optical module is defined by 4WDM MSA, targeted for longer reaches, lower costs, and lower power consumption, smaller form factor(QSFP28 form factor is usually preferred). 100G QSFP28 4WDM optics have three specifications including 4WDM-10, 4WDM-20, 4WDM-40. 4WDM-10 is one type of 100G (4x25G) optical transceivers for the 10 km based on the CWDM4 wavelength grid; 4WDM-20 and 4WDM-40 are types of 100G (4x25G) optical transceivers respectively for 20kms and 40kms based on the LAN-WDM wavelength grid over duplex single-mode fiber (SMF). With respect to the benefits of 4WDM, its main advantages are lower in cost and power dissipation, and longer in transmission distance.
An Introduction to QSFP28 ER4 Lite Optical Transceiver
IEEE 802.3ba defines that the 100GBASE-LR4 / 100GBASE-ER4 series has a BER requirement of better than 1E-12 w / o FEC for optical modules. Since the receiving sensitivity of 100GBASE-ER4 is not satisfied with the existing APD technology, the SOA size is too large for the QSFP28 series; many optical module companies in the industry defined a non-standard 100GBASE-ER4 Lite with QSFP28 package that the largest transmission distance is up to 30km without FEC.
The receiving sensitivity of 100GBASE-ER4 Lite 30km has no clear definition in IEEE802.3ba. At the current level of 100G APD ROSA, the average of OMA Sensitivity is around -17dbm (BER 1E-12@25.78125Gbps). The description of the100GBASE-ER4 Lite products in the industry is defined as 30km w/o FEC, 40km with FEC.
100G QSFP28 ER4 Lite vs. 100G QSFP28 4WDM: What Are the Difference?
The differences between QSFP28 ER4 Lite and QSFP28 4WDM are shown as the table:

QSFP28 4WDM vs. QSFP28 ER4 Lite

In addition, in the aspect of application, 100G QSFP28 ER4 Lite is available for both 100GE and OTU4 application, while 100G QSFP28 4WDM 40km is only available for 100GE application.
Summary
The migration of current network infrastructure to 100G systems is inevitable, and a growing number of enterprises require 100G client port to extend up to 40km without the use of expensive optical amplifiers. Thefore, the new ER4 Lite and 4WDM optical transceiver enable cost-effective 100G 40km pluggable solutions in compact QSFP28 transceivers that use Forward Error Correction (FEC) and APD-based receivers. Such evolution is very exciting for not only everyone involved in its development and construction, but also for all those who seek a simple, reliable and cost-effective solution to extend the reach of their networks, without expensive network upgrades. Gigalight, as the design innovator in global optical interconnect field, has pushed out the latest 100G QSFP28 4WDM 40KM optical transceiver and 100G QSFP28 ER4 Lite 40KM optical transceiver. More details are at Gigalight(gigalight.com)