1   Overview

3Coptics's QSFP28 ZR4 is designed for 100 Gbps Ethernet 80km applications.

It is intended for use between data centers between switches, routers, trasmission equipment etc, and the optical distance is up to 80km over a SingleMode (SM) fiber.

The transceiver integrates the receiver and transmit path on one module. On the transmit side, four lanes of serial data (NRZ) are recovered by a CDR and passed to four laser drivers, which control four lasers with center wavelengths of 1296 nm,1300nm,1305nm and 1309nm. The optical signals are multiplexed to a single mode fiber through an standard LC connector. On the receiver side ,four lanes of optical data streams are amplified by an SOA, then the optical signal are de-multiplexed by an integrated optical demultiplexer. Each data stream is recovered by a PIN detector, then through the transimpedance amplifier and CDR pass to a CAUI-4 compliant output driver. A block diagram is shown in Figure 1.

2   Application Notes

Metro and DCI, referring to hypercale data centers and large inernet exchanges connected inside the city and who requie many high bandwidth connections at 100G+ data rates. The focus on simplified operation, less space, low cost, and low power consumption.

Traditionally, switch vendors using CFP/CFP2 transceiver types with their equipment for DCI.

However, the dedicated line card is necessary because of the big power consumption, large size of CFP/CFP2 modules. Recent developments in direct detect 100G transceivers, for example, QSFP28 PAM4 DWDM transceiver, provide another option. The main disadvantage is that PAM4 requires amplification and dispersion compensation system on the optical link for reach longer than 5km at 100Gbits, which induce that the end-to-end cost is higher. The DCI operator needs to deploy the Mux/Demux, EDFA, and DCM, which may do not exist in the current network. 

However, QSFP28 ZR4 overcome the drawbacks of CFP/CFP2 for their large form factor and high power consumption; at the same time, it can reach up to 80km and deployed based on dark fiber, without considering DWDM components, which is a true plug-and-play solution. s shown in Figure 3 below:

3. Solutions to achieve 100G Transmission using 100G-QSFP-ZR4:

1) Working along with 100G CFP module can achieve multi-channel 100G ultra-long distance transmission

2) Working along with 200G CFP2 module can achieve multi-channel 100G ultra-long  distance transmission (also can improve the transmission density of 100G)

3) Converted to 4*25GDWDM through OTU board (suitable for 100G transmission below 80KM, advantage in cost)

4   Summary

100GE QSFP28 ZR4 module can support 80km based on SM fiber, low cost, low power consumption, compact, plug and play, which is dedicated for metro and DCI scenario.