What You Should Know about 40G QSFP+ ER4 and ZR4

40G optical modules can provide high-density and low-power 40G Ethernet high-speed interconnection for data centers, high-performance computing networks, and telecom operators. Common packaging forms of 40G optical modules are CFP, QSFP, and QSFP+ optical modules. Among them, 40G QSFP+ optical modules are products developed based on QSFP and are dedicated to high-density applications. Compared with traditional SFP+ optical modules, they have higher port density and lower overall system cost.

40G QSFP+ optical modules are mainly divided into SR4, SR BIDI, LR4, ER4, ZR4 and other models. Among them, ER4 and ZR4 are long-distance transmission optical modules. Next, let's take a look at how ER4/ZR4 optical modules achieve ultra-long-distance transmission and what the difference is between the two.

40G QSFP+ ER4

YXF-QP-S31L-40D

It is designed to operate in single-mode fiber systems using 4X10 CWDM channels in the 1310 band, with a link transmission distance of up to 40 km. The module converts 4 10Gb/s electrical data input channels into 4 CWDM optical signals and multiplexes them into a single channel for 40Gb/s optical transmission. Conversely, at the receiving end, the module demultiplexes the 40Gb/s input signal into 4 CWDM channel signals and converts them into 4 output channel electrical data.

The center wavelengths of the 4 CWDM channels are 1271, 1291, 1311, and 1331 nm, respectively. It contains a duplex LC connector for the optical interface and a 38-pin connector for the electrical interface. This module uses single-mode fiber (SMF). The product converts 4 channels of 10Gb/s electrical input data into CWDM optical signals (light) through a four-wavelength distributed feedback laser (DFB) array. The 4 wavelengths are multiplexed into 40Gb/s data and output from the transmitter module through a single-mode fiber (SMF). The receiver module receives the 40Gb/s optical signal input and demultiplexes it into 4 CWDM 10Gb/s channels. The light of each wavelength is collected by a discrete photodiode and then amplified by the TIA and output as electrical data.

The product is designed with form factor, optical-electrical connections, and digital diagnostic interfaces according to the QSFP+ Multi-Source Agreement (MSA), and complies with the 40G QSFP+ ER4 standard of IEEE 802.3ba.

40G QSFP+ ZR4

YXF-QP-S31L-80D

It is a transceiver module designed for 80km optical communication applications. The design complies with the 40GBASE-ER4 standard of the IEEE P802.3ba standard. The module converts 4 10Gb/s electrical data input channels into 4 CWDM optical signals and multiplexes them into a single channel for 40Gb/s optical transmission. Conversely, at the receiving end, the module demultiplexes the 40Gb/s input signal into 4 CWDM channel signals and then converts them into 4 output electrical data channels.

The center wavelengths of the 4 LANWDM channels are 1296 nm, 1300 nm, 1305 nm, and 1309 nm, respectively, which belong to the LAN WDM wavelength grid defined by ITU-T G694.2. The module contains a duplex LC connector for the optical interface and a 38-pin connector for the electrical interface. To minimize optical dispersion in long-distance systems, this module must use single-mode fiber (SMF).

The product is designed according to the QSFP Multi-Source Agreement (MSA) and its size, optical and electrical connections, and digital diagnostic interfaces are all standard. It is designed to meet the most stringent external operating conditions, including temperature, humidity, and EMI interference.

The module operates from a single +3.3V power supply and provides LVCMOS/LVTTL global control signals such as module presence, reset, interrupt, and low-power mode. The module also has a two-wire serial interface for sending and receiving more complex control signals and obtaining digital diagnostic information. The interface supports addressing individual channels and can shut down unused channels for maximum design flexibility.

The product is designed according to the QSFP Multi-Source Agreement (MSA) and its size, optical and electrical connections, and digital diagnostic interfaces are all standard. It is designed to meet the most stringent external operating conditions, including temperature, humidity, and EMI interference. The module provides extremely high functionality and feature integration through a two-wire serial interface.