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Do You Know These about QSFP28 PSM4 Optics?

Although there have been 200G/400G optical transceiver products appearing in the optical communication market, and it does not mean that the era of 100G optical transceiver module has come to end. Actually, there still are various 100G QSFP28 optical module in great favour, such as 100G QSFP28 PSM4 and 100G QSFP28 CWDM4 optical transceiver, which meet users’ requirements for transmission distance and costs well. Then today let’s talk about the QSFP28 PSM4 optical transceiver in this post(QSFP28 CWDM4 optics has been talked about in the last post).

What Is 100G QSFP28 PSM4 Optical Transceiver?

PSM4, the abbreviation of Parallel Single Mode 4-channels, a optics with parallel technology, defined by the 100G PSM4 MSA(Multi-Source Agreement). It uses four lanes of parallel single fiber to deliever serialized data at a rate of 25Gbps per lane. 100GE PSM4 QSFP28 will be the optical transceiver that enables single-mode fiber to become popular in next-generation data centers due to its low cost and high configurability. It doesn’t need a MUX/DEMUX for each laser but it does need a directly modulated DFB laser (DML) or an external modulator for each fiber. QSFP28 100G PSM4 uses eight fibers, in which four fibers are for transmitting and four fibers are for receiving. A PSM4 QSFP28 optical module supports link lengths of up to 500 meters over single-mode fiber with 12 fiber MTP/MPO connectors. The light source of QSFP 100G PSM4 optic module is a single uncooled distributed feedback (DFB) laser operating at 1310nm.

qsfp28 psm4 optics

Why Is 100G QSFP28 PSM4 Optical Transceiver In Demand?

It is known that the most basic 100G interfaces currently used are 100GBASE-SR4 and 100GBASE-LR4 which are defined by IEEE. However, there exists a problem between them that reaches are either too short for practical application in data center or too long and costly. In fact, for data center operators, a 100G QSFP28 optical transceiver that is with max reach of 2km or min reach of 500m is better. Thus, MSA (Multi-Source Agreement) brings a mid-reach solution to the market. And 100G QSFP28 modules with PSM4 interface are the products in this revolution. They are much less expensive than the 10km 100GBASE-LR4 modules, and support longer distance than 100GBASE-SR4 QSFP28 optical modules.

What Are the Advantages of QSFP28 PSM4 Optical Transceiver?

In addition to the common merits of QSFP28 transceiver module, such as high bandwidth, low insertion loss, high data rate and so on, the most prominent advantage of QSFP-100G-PSM4-S is shown in its cost. It is known that CWDM4 QSFP28 optical transceiver needs an optical multiplexer/de-multiplexer, operating around 1310nm with CWDM technology. After that, the amount of the components leads to the high cost of 100G QSFP CWDM4 modules. While 100G QSFP28 PSM4 optics, unlike 100G QSFP28 CWDM4, need these components. Thus, by comparison, CWDM4 is more expensive than PSM4. As for the other types, QSFP28 100G SR4 or QSFP28 100G LR4, both are known to be high in cost.

Factors to Be Considered for the Deployment of QSFP28 PSM4 Optical Transceiver

Compared with 100GBASE-LR4, the cost of 100GE PSM4 QSFP28 optical transceiver module is much lower. But QSFP28 PSM4 needs to connect with eight parallel single-mode optic fiber for use, while 100GBASE-LR4 optical transceiver just needs 2 single-mode optic fibers. After that, if the optical fiber link is too long, QSFP 100G PSM4 optical transceiver module will have less advantages in the deployment cost. Therefore, when deploying PSM4 QSFP28, these two aspects need to be considered: parallel single-mode optic fiber has been deployed in data center; the transmission distance of optical fiber link is within 500m.


All in all, 100GE PSM4 QSFP28 optics provides a cost-effective solution for the users who demands mid-reach transmission at low cost. Above all is about the contents Gigalight wants to share with you. If you want to know more about it, welcome to visit Gigalight official website(

About Gigalight:

Gigalight is a design innovator in global optical interconnect field. A series of optical interconnect products include: optical transceivers, passive optical components, active optical cables, GIGAC MTP/MPO cabling, cloud programmers & checkers, etc. Three applications are mainly covered: Data Center & Cloud Computing, MAN & Broadcast Video, and Mobile Network & 5G Optical Transmission. Gigalight takes advantage of its exclusive design to provide clients with one-stop optical network devices and cost-effective products.

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