As a member of the new QSFP28 family, the 100G QSFP28 SR4 optical module is a very ideal solution in the short distance transmission of 100g network. The application of 100G will be more and more put into the actual environment. So what is the connection solution of 100G QSFP28 SR4 and what fields are it applied in? ETU-Link will unveil it for you.

Ⅰ. Technical Background Of 100G Optical Module Transmission & QSFP28 SR4 Positioning

Compared with 2.5G, 10G or 40G WDM systems, 100G optical transmission uses digital coherent receiver to map all optical attributes of optical signal to the electric domain through phase diversity and polarization state diversity. Using mature digital signal processing technology, polarization demultiplexing, channel damage equalization compensation, timing recovery, carrier phase estimation, symbol estimation and linear decoding are realized in the electric domain. While realizing 100G optical transmission, a series of significant technical changes have taken place in 100G optical module, including polarization multiplexing phase modulation technology, digital coherent reception technology, the third generation of super strong error correction coding technology, etc., which meets the needs of users with the times.

Ⅱ. Functional Characteristics of 100G QSFP28 SR4 Optical Modules

(1) It can transmit 70m in OM3 multimode fiber and 100m in OM4 multimode fiber

(2) Comply with QSFP28 MSA standard

(3) Comply with IEEE 802.3bm* 100Gbase-SR4

(4) The transmitter adopts 4x 25Gbps 850nm VCSEL

(5) The connector adopts 4x 25Gbps Electrical I/O

(6) Working temperature 0°C～70°C。

(7) Optical connector adopts Male MPO(MTP) receptacle。

(8) Support DDM function

Ⅲ. 100G QSFP28 SR4 Standard Point‑to‑Point Connection Solution

100G is composed of four 25G channels, using MPO / MTP backbone jumper to realize direct data transmission of 100G QSFP28 SR4 Optical Module.

Critical deployment notes for point‑to‑point link:
1. Strictly use OM3 / OM4 multimode MPO‑12 trunk cable; OM1 multimode fiber cannot satisfy 100G SR4 bandwidth requirement and will bring high bit‑error rate;
2. Pay attention to MPO polarity (Type A / Type B mismatch will cause all lanes no‑link);
3. Clean MPO ferrule end‑face with dedicated MPO cleaning tool before plug‑in, dust contamination is the top cause of unstable 100G parallel‑lane links;
4. Actual physical cable length cannot exceed 70m for OM3 and 100m for OM4, do not over‑stress nominal maximum distance;
5. Verify that the switch QSFP28 port enables 100GBASE‑SR4 mode, avoid mis‑configuration to LR4 or other rate modes.

With the wide application of 100G network technology, the use of 100G optical module has become more and more common and cost-effective.

Last updated: Sept. 20 2026