Exploring the Features and Applications of the 100G QSFP28 Multimode Optical Transceiver Modules

As cloud computing and 5G networks continue to proliferate, the expansion of data centers is accelerating, consequently driving up the demand for 100G transceiver modules. These modules constitute a significant portion of the overall network construction costs. Within the confined environments of data centers, the majority of fiber links, particularly in small to medium-sized facilities, span distances of less than 100 meters. Even in larger data centers, a substantial portion of fiber links—more than 70%—are under the 100-meter mark, with over 80% falling short of 125 meters.

Given these prevalent short-distance requirements, multimode fiber emerges as the preferred solution for most data center links. Consequently, the 100G multimode module emerges as the most sought-after option. Among the array of solutions available, the QSFP28 100G multimode module stands out with its versatility. The primary contenders in this category include the 100GBASE-SR4, 100GBASE-SR BD, 100GBASE-SWDM4, and 100G QSFP28 BiDi SR1.2. Each offers distinct advantages tailored to specific networking needs, ensuring that data centers can optimize their infrastructure to meet evolving demands while managing costs effectively.

Introducing 100G QSFP28 Multimode Transceiver Modules

100G QSFP28 SR4

• The 100G QSFP28 SR4 module is designed for high-speed, short-range data transmission over multimode fiber.

• It operates at a wavelength of 850nm and supports a transmission distance of up to 100 meters.

• With its four parallel lanes, this module can achieve a data rate of 100 Gbps, making it ideal for data center and enterprise networking applications.

100GBASE-SR BD

• The 100GBASE-SR BD module offers a cost-effective solution for short-range data transmission in data center environments.

• It utilizes a bidirectional (BiDi) transmission scheme, allowing data to be transmitted and received over a single fiber strand.

• Operating at a wavelength of 850nm, it supports transmission distances of up to 100 meters over OM4 multimode fiber.

100GBASE-SWDM4

• The 100GBASE-SWDM4 module employs Short Wavelength Division Multiplexing (SWDM) technology to achieve high-speed data transmission over duplex multimode fiber.

• It utilizes four different wavelengths within the 850nm spectral window, enabling transmission distances of up to 150 meters over OM4 fiber.

• This module provides a cost-effective solution for upgrading existing multimode infrastructure to support higher data rates.

100G QSFP28 BiDi SR1.2

• The 100G QSFP28 BiDi SR1.2 module offers a compact and efficient solution for short-range data transmission in data center and campus networking environments.

• It utilizes bidirectional transmission over a single fiber pair, reducing fiber cabling requirements and simplifying installation.

• With its enhanced SR1.2 standard, this module supports transmission distances of up to 70 meters over OM3 multimode fiber, making it suitable for high-density deployments.

Application Selection of 100G QSFP28 Multimode Modules

100G QSFP28 SR4

Within the realm of 100G multimode modules, the 100GBASE-SR4 emerges as the frontrunner in widespread adoption. This module, the 100G QSFP28 SR4, epitomizes a hot-pluggable, full-duplex optical marvel, boasting a center wavelength of 850nm and adhering meticulously to IEEE 802.3BA standards. Its niche lies in catering to short-distance transmissions within the realm of 100G Ethernet networks. Remarkably, the 100G QSFP28 SR4 optical module is endowed with four autonomous transmit and receive channels, each operating at a formidable rate of 25Gbps. Leveraging either MPO or MTP interfaces (comprising 8 cores), this module exhibits impressive transmission capabilities, spanning 70m when paired with OM3 multimode fiber and extending up to 100m with OM4 multimode fiber. The working principle is as follows:

100G QSFP28 SR BD

In contrast to its SR4 counterpart, the 100G QSFP28 SR BiDi (Bidirectional) module adopts an innovative approach, harnessing WDM (Wavelength Division Multiplexing) technology to enable each LC port to concurrently transmit and receive optical signals of distinct wavelengths via a single multimode fiber. This ingenious design allows for a total transmission capacity of 100G across the two LC interfaces. Operating on a dual-wavelength VCSEL bi-directional optical interface, these modules excel in PAM4 2 × 50-Gb/s transmission, leveraging wavelengths of 850nm and 900nm. Their versatility shines through as they seamlessly integrate with multimode fiber systems, enabling transmissions of up to 70 meters with OM3 fiber patch cables, up to 100 meters with OM4 fiber patch cables, and extending up to an impressive 150 meters with OM5 fiber patch cables. The operational principle of these modules underscores their efficacy in optimizing network performance while ensuring seamless data transmission across diverse networking environments. The working principle is as follows:

100G QSFP28 SWDM4

The 100GBASE-SWDM4 shares similarities with the 100G QSFP28 SR BiDi in their utilization of duplex LC interfaces. SWDM, standing for short-wave wavelength division multiplexing, parallels the concepts of CWDM4 and LWDM4 in single-mode configurations. Through the ingenious application of MUX/DMUX technology, SWDM4 achieves the simultaneous transmission of optical signals across four distinct wavelength bands over a single multimode fiber core. These wavelength bands, spanning 850nm, 880nm, 910nm, and 940nm, enable robust data transmission capabilities. Notably, the 100GBASE-SWDM4 module exhibits remarkable transmission distances, reaching up to 70 meters with OM3 fiber patch cables and extending to 100 meters with OM4 fiber patch cables. The working principle is as follows:

100G QSFP28 BiDi SR1.2

As mission-critical workloads like artificial intelligence (AI) and machine learning drive up computing and traffic demands within data centers, there's a pressing need for denser and faster connections along the ridges and backbones of these structures, as well as between ridge/rack top switches and servers. However, traditional data center upgrades from 10G to 40G or 100G often entail converting LC duplex cabling connecting to SFP optical modules to MPO cabling connecting to QSFP optical modules, resulting in increased operating costs. Simplifying wiring and reducing capital expenditure becomes paramount in such scenarios. Enter the optical module using the BiDi solution, exemplified by the 100G QSFP28 BiDi SR1.2.

Similar to its 40G QSFP+ SR BiDi counterpart, the 100G QSFP28 BiDi SR1.2 empowers data center operators to leverage their existing duplex LC jumper infrastructure when transitioning from 10G SR or 40Gb BiDi to 100G. This facilitates a seamless upgrade process, enabling carriers to flexibly enhance their data centers by upgrading network devices one terminal at a time.

The 100G QSFP28 BiDi SR1.2 is a Quad Small Form-factor Pluggable (QSFP28) BiDi optical module engineered to support 100Gbps data transmission while adhering to the IEEE802.3bm 100GBASE-SR4 standard. Leveraging dual-core duplex LC multimode optical fiber, the module employs 4×25G NRZ modulation at the electrical end, which seamlessly converts to 2x50Gbps PAM4 modulation at the optical end, achieving a total bandwidth of 100Gb. PAM4 technology facilitates signal transmission at both 50Gb data rates and 25Gbaud rates, ensuring optimal performance and efficiency in high-demand data center environments.

The 100G QSFP28 SR BiDi is used in pairs for 100G connectivity and can also be connected to the 400G QSFP+ SR BiDi in 4 x 100G branch mode.

While all four modules utilize multimode optical fibers, their technical approaches differ significantly. The 100G QSFP28 SR4 module employs a four-channel parallel transmission method, requiring eight optical fibers for complete transmission (four for receiving and four for transmitting). In contrast, the 100GBASE-SR BD module uses a single optical fiber for transmitting and receiving 50G data, allowing both interfaces to jointly transmit 100G data. Similarly, the 100GBASE-SWDM4 module utilizes wavelength-division multiplexing (WDM) to merge signals across four distinct bands into a single optical fiber, requiring two fibers for efficient data transmission.

All modules are compatible with the widely used 100G QSFP28 port, ensuring seamless integration into existing networking infrastructures. Although there are significant differences in technical specifications, their applications demonstrate minimal disparity. In terms of fiber resources and cabling costs, the 100GBASE-SR BD and 100GBASE-SWDM4 modules are advantageous, requiring only a quarter of the fiber resources compared to the 100GBASE-SR4 module. This efficiency translates to significant savings in capital expenditure for fiber infrastructure. However, it's important to note that the upfront costs of the 100GBASE-SR BD, 100G QSFP28 BiDi SR1.2, and 100GBASE-SWDM4 modules are higher than those of the 100GBASE-SR4 module. Therefore, when considering the overall cost of the optical module coupled with fiber infrastructure, selecting the appropriate product based on actual program needs is recommended.

Conclusion

For short-distance connections within data centers, FS offers a comprehensive solution. FS provides options like the 100G QSFP28 SL4、100G QSFP28 BiDi SR1.2 and 100G QSFP28 SWDM4, all of which seamlessly integrate with duplex LC multimode jumpers. This versatility extends to the replacement of conventional optical modules such as the 100G QSFP28 SR4, resulting in substantial savings in optical fiber resources and streamlining fiber management within the data center environment.