Long-range 100G QSFP28 ZR4 transceivers go the distance for rural telecom


With the demand for higher bandwidths and long-haul distances increasing across the telecommunications industry, stimulating cloud traffic, network and data center growth, there is a search for solutions that are high bandwidth, extended range and, of course, cost-effective.

Introducing the 100G QSFP28 ZR4 – available in 80km and 100km.

5 network architecture options for 100G long-range (40km+) transmission

  1. Mux-ponder (10G DWDM + Mux/Demux + 80km + EDFA)
  2. O-E-O Repeaters (100G 40km + Repeater + 40km)
  3. Coherent DWDM, CFP/CFP2
  4. QSFP28 100G-DWDM PAM4 (with EDFAs and DP compensation for reach >5km)
  5. 100G QSFP28 ZR4 — a single, simple solution for long distance data transmission
    • Significantly reduced complexity for ordering, stocking, and installation
    • Significantly reduced cost
    • LAN-WDM wavelength spacing

Applications for 100G QSFP28 ZR4

The 100G QSFP28 ZR4 offers the advantage of point-to-point interconnect and routing applications between data centers and between data center and central offices without the use of complicated, power-hungry and expensive coherent solution or legacy CFP/CFP2. For rural telecom operators searching for middle mile solutions, the 100G ZR4 is compelling.

100G QSFP28 ZR4 technical overview

The 100G ZR4 follows the QSFP28 form factor, the smallest for 100G long-range solutions, with the ability to transmit four 25G wavelengths: 1295.56nm, 1300.05nm, 1304.58nm, and 1310.19nm.

It is fully compliant with the QSFP28 MSA industry standard and IEEE 802.3 100GBASE-ZR4 specifications. The transceiver also supports KR-4 FEC (Forward Error Correction) which detects and corrects errors, enhancing the quality and performance of the module. For applications that require improved latency, such as DCI, the 100G ZR4 can be used without FEC for up to 60km of reach.

Watch “The pros & cons of FEC in data center & telecom optical networks” >

Vitex ProductReachTypeConnectorTx (Avg.)RxPs (Avg.)Extinction Ratio@ BERPowerCase Temp.
Duplex LC2 dBm-27 dBm8 dB min.5e-56.5W0-70°C
Duplex LC4.2 dBm-30 dBm6 dB min.5e-57W0-70°C
  • Form factor : QSFP28
  • Data format: 25.78125Gbps NRZ (CEI-28G-VSR)
  • Configuration: 4 lanes x 25G (electrical) => 4λ x 25G multiplexed into 1 fiber
  • Wavelengths: 1295.56nm, 1300.05nm, 1304.58nm, 1309.14nm (LAN-WDM)
  • Power consumption: 4.5W (35C), = 5.5W (65C)
  • Large power budget: 60km
  • Support 60/65Km without FEC, or 80km with KR-4 FEC for NRZ

Why 1310nm? (instead of 1550nm)

The Vitex 100G QSFP28 ZR4 transceiver family is designed with a 1310nm laser as the wavelength is at a higher overall performance than 1550nm when used for long-distance data transmission. Specifically, the attenuation for both is comparable, but the dispersion penalty at 1550nm is very large. (See Fig 1.) A simple link calculation using this dispersion penalty for an 80km transceiver results in a poor link length of about 40km.

Fig. 1: Comparison of 1310nm and 1550nm over standard single-mode fiber

100G QSPF28 ZR4 transceivers leverage the widely deployed 4x 25G NRZ optics without the need for optical amplification and dispersion compensation.


10G links for metro and access networks typically use Avalanche Photo Diodes (APD). The ZR4 modules that operate at a line speed of 25G go through severe signal degradation after 80km, and the APDs do not provide adequate gain at the overall bandwidth to meet the bit error ratio criteria.

When long distance, over 25 miles, is a primary use case the use of Semiconductor Optical Amplifiers (SOAs) before the PIN photo diode provides sufficient optical gain over the band of 4 WDM channels while meeting the BER requirements.

The 100G QSFP28 ZR4 takeaways

For optical applications that require long haul architecture of <40km, <80km and <100km, the 100G QSFP29 ZR4 family is an easy to order, easy to stock, easy to install option.

To view detailed product specifications, go to our complete 100G QSFP product page and scroll through the table by “reach. For every product we sell, Vitex offers customization and application-specific development options.

For questions, a product sample or to talk to an applications engineer, contact us.

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