How Does 100G Transceiver Reach to 100 Gbps Transmission Capacity?

With the demand of data centers for higher transmission speed and higher capacity bandwidth, 100G Ethernet now accounts for a higher and higher proportion in the market. More and more data centers begin to develop 100G Ethernet data transmission. According to the report of IHS Infonetics, at present, more than 50% of data centers are enjoying the excellent performance brought by 100G transceivers. Do you know how a 100G transceiver reaches 100Gbps transmission capacity? This post will introduce different types of QSFPTEK 100G transceivers in detail.

100G Transceiver Transmission Principles

QSFP28 100G SR4

QSFP28 SR4 optical module is a hot-pluggable full-duplex transceiver, it is commonly used for transmitting 100G Ethernet data in a short-range, and its working wavelength is 850nm. Due to its miniaturization design, the QSFP28 SR4 size is smaller than the 100G CFP/CXP transceiver. The power consumption of QSFP28 SR4 is usually 3.5W or less. The QSFP28-100G-SR4 is standardized by IEEE 802.3ba compliant, SFP28 MSA standard, SFF-8665, SFF-8636, RoHS, CPRI, and eCPRI. The working principle is transmitted or received data from four independent channels. Thus the single data rate of the four channels is 25Gbps aggregate into 100G data rate.

QSFP28 SR4 transmits parallel optical signals through the transmitting end. It uses the layer array to convert the input parallel electrical signals into parallel optical signals. Meanwhile, because the input signals are parallel signals, it is matched for MTP/MPO multimode ribbon fiber for parallel transmission. After the signals arrive at the receiving terminal, it converts the optical signals into electrical signals through the PIN array, same to the transmitting end, this is also a parallel electrical signal. The maximum transmission distance is up to 70m over OM3 fiber and 100m over OM4 fiber. The 100GBASE SR4 module can be connected to a 12-fiber MMF strand MTP/MPO up to 100m.

Figure 1: QSFP28 SR4 Working Principle

QSFP28 100G PSM4 

The QSFP28 100G PSM4 is a hot-pluggable optical transceiver module, it features low power consumption and a built-in digital diagnostics function. PSM4 MSA standardizes the 100GBASE PSM4.The difference between psm4 and sr4 module is that psm4 works at 1310nm. Besides, the power consumption of psm4 is less than 3.5w. It’s depolyed for Singlemode long-haul transmitting up to 500m over 12 fiber MTP/MPO connectors.

The working principle of 100GBASE PSM4 is similar to that of the 100GBASE SR4 module. It is also transmitted through four separate channels. The single-channel transmission rate is 25Gbps. The electrical input signals are converted into parallel optical signals through the Layer array internally. The parallel optical signal is converted to a parallel electrical signal, which is different from QSFP28 SR4 in that it is used for single-mode fiber, while QSFP28 SR4 is usually used for multi-mode fiber.

Figure 2: QSFP28 PSM4 Working Principle

100GBASE CWDM4

The QSFP28 CWDM4 is designed for 100G Ethernet data transmission, it is fully compliant with the QSFP MSA, CWDM4 MSA, and IEEE P802.3bm protocol. The 100GBASE CWDM4 working principle is to convert input electrical data to CWDM optical signals, and there are four independent channels of 25Gbps multiplex to a single 100Gbps channel. Meanwhile, in the receiving terminal, the QSFP28 CWDM4 de-multiplexes a 100Gb/s optical input signal to 4 independent output electrical data.

It usually transmits data through a single-mode fiber up to 2km, there are four main wavelength ranges, L0: 1271nm(1264.5-1277.5nm), L1: 1291nm(1284.5-1297.5nm), L2: 1311nm(1304.5-1317.5nm), L3: 1331nm(1324.5-1337.5nm) and its power consumption is no more than 3.5W. Ituse an industry-standard LC connector to multiple and couple four optical signals from four wavelengths to the Singlemode fiber.

Figure 3: QSFP28 CWDM4 Working Principle

100GBASE-LR4

The QSFP28 LR4 transceiver is fully compliant with IEEE802.3ba and designed for hot-pluggable, full-duplex, four transmitting channels inside. It applys for 100G Ethernet long-haul transmitting and the maximum transmission up to 10km. The working wavelength range is 1295 to 1310nm.  The 100GBASE LR4 meets the ever-lasting requirement of high-performance computing and super large scale data centers.

A 100GBASE LR4 transceiver can convert four independent channels of 25Gbps electrical signals into optical signals of four independent channels. Then the QSFP28 LR4 module multiplexes the optical signal into a single channel for a 100G optical link connection. At the receiving terminal, the module converts the optical input signal into LAN WDM optical signal with four channels separately, and then it will convert the optical signal into four electrical channel signal output channels.

Figure 4: QSFP28 LR4 Working Principle

QSFP28 ER4 

The 100GBASE ER4 optical transceiver is fully compliant with the QSFP MSA, IEEE 802.3ba 100GBASE-ER4 Lite, and OTU4 standard protocol, the QSFP28 ER4 is used to transmit the Singlemode signal by the dense wavelength division multiplexing technology. This optical module is designed for single-mode optical fiber cables and its working wavelength is 1310nm, the maximum power consumption of QSFP28 ER4 is 4.5W. By using a semiconductor optical amplifier (SOA) to amplify the optical signal before entering the PIN photodetector, the transmission distance of ER4 has been greatly improved, the maximum transmission distance is up to 40km.

The 100GBASE ER4 optical transceiver working wavelength is the LAN WDM wavelength(1295nm, 1300nm, 1305nm, 1310nm). The 100GBASE ER4 can multiplex four wavelengths of optical signals it is usually connected to the single-mode fiber through an industry-standard LC connector, besides, WDM MUX, the wavelength signals can be aggregated onto an SMF fiber to form a 100G optical signal transmission. As for the receiver, the semiconductor optical amplifier can help the module to amplify the signals before a WDM demux splits the signals into four independent data transmit channels.

Figure 5: QSFP28 ER4 Working Principle

Conclusion

After introducing these different 100G optical modules, I believe that you already know the working principle of these different modules and how they reach 100G transmission rate. QSFPTEK provides various compatible 100G optical modules. In addition, QSFPTEK offers 100G transceivers with QSFP28 form factors, enabling cost-effective, high-density, and low-power 100G Ethernet connectivity solutions for data center, distribution layers, and service provider applications. Contact our customer service for quotation via [email protected].