400G ZR, DR4, FR4, LR4, SR8 QSFP-DD Optical Transceiver Overview

Optical transceivers are key devices to realize optical network interconnection in the data center. As the number and density of ports go on, data centers have to take the cost of optical modules into consideration since it is expected to account for nearly half of the cost of optical networks in IDC. At present, the newly-built data centers of major Internet companies are looking to make a transition to 400G Ethernet. 400G QSFP-DD optical modules are the most common optical solutions for the 400G high data rate network connectivity. A brief introduction of 400G QSFP-DD optics will be given in this post.

What is QSFP-DD in the 400G Transceiver Module?

QSFP-DD, an abbreviation of Quad Small Form-factor Pluggable (QSFP) – Double Density (DD), is a high-speed hot pluggable form factor defined by the QSFP-DD MSA group as a key part of the optical communication industry to achieve high-density networking. As the best option for the 400G optical transceiver form factor, this QSFP-DD connector enables data centers to effectively grow and expand cloud capacity as needed. 

QSFP-DD is forward and backward compatible with the QSFP port and is also compatible with the existing QSFP28 optical modules and AOC/DAC, etc. The electrical interface of a QSFP-DD connector consists of 8 electrical lanes,  running at 25Gb/s NRZ signal or 50Gb/s PAM4 signal each for a total bandwidth of 200Gb/s or 400Gb/s. QSFP-DD can achieve up to 14.4Tb/s aggregated bandwidth in a single switch slot.

Optical Interface

Optical Signal Rate

Transmission mode


Electrical Signal  Rate

Form Factor


16*26.5Gbps NRZ

100m MM


16*26.5Gbps NRZ



8λ*53Gbps PAM4

2km SM


8*53Gbps PAM4



8λ*53Gbps PAM4

10km SM


8*53Gbps PAM4



8λ*53Gbps PAM4

100m MM


8*53Gbps PAM4



4*2λ*53Gbps PAM4

100m MM(2λ)


8*53Gbps PAM4



4*106Gbps PAM4

500m SM


8*53Gbps PAM4



4*106Gbps PAM4

2km SM

100G/λ MSA

8*53Gbps PAM4



4*106Gbps PAM4

10km SM


8*53Gbps PAM4



DWDM+59.8Gbd DP-16QAM

>80km DWDM




 Technical Indicators for Different 400G Fiber Transceiver Types


What are the Common 400G Transceiver Types in the Market?

● 400G DR4 QSFP-DD Transceiver

400G DR4 is an optical transceiver module designed for 400G Ethernet data center interconnect in QSFP-DD (Quad Small Form Factor Pluggable-double density ) form factor. On the transmitter end, this DR4 module converts 8 channels of 50Gb/s (PAM4) electrical signal into 4 channels of parallel optical output data, each capable of 100Gb/s data rate for an aggregated bandwidth of 400Gbls. On the receiver side, the optic transceiver converts 4 lanes of parallel optical data of 100Gbp/s each lane for an aggregated of 400Gbp/s to support 8 lanes of 50Gb/s PAM4 electrical output signal.

QSFP-DD-400G-DR4 400G QSFP-DD DR4 Optical Transceiver Module with MTP/MPO connector and 1310nm SMF

Fiber Mall 400G DR4 QSFP-DD Optical Transceiver Module


The 400G QSFP-DD DR4 fiber module achieves the transmission over SMF(single-mode fiber) with an MPO-12 connector. Normally, the 400G transceiver of QSFP-DD DR4 form-factor supports a max transmission distance of 500 meters on 1310nm center wavelength. The product is designed with digital diagnostic functions according to the 400G QSFP-DD Multi-Source Agreement (MSA).

● 400G FR4 QSFP-DD Optical Transceiver

The 400GBASE-FR4 module is a 400Gbps hot-pluggable transceiver in a QSFP-DD form factor that supports 8 high-speed electrical interfaces connecting to the host. The 400G FR4 transceiver incorporates 4 independent lanes on CWDM4 center wavelengths of 1271/1291/1311/1331nm running at 100Gbps per lane. 4 uncooled 100 Gbps CWDM EMLs are used in the DSP AND EML lasers as an optical drive with an optical multiplexer. It is designed with a duplex LC connector for the optical interface to support up to 2km transmission for 400G Ethernet links over single-mode fiber (SMF). 400G FR4 QSFP DD fiber transceiver module follows a similar protocol of 100G Single Lambda MSA specification for 400G FR4 and QSFP-DD MSA specification.

400G QSFP-DD FR4 Optical Module with duplex LC connector

 Diagram of 400G FR4 QSFP-DD Transceiver Module with Duplex Fiber


● 400G LR4 QSFP-DD Transceiver Module

400GBase LR4 fiber optic modules are designed with a built-in Gearbox chip that multiplex the two channels’ electrical input data into single-channel outputs signal and then modulates it to the optical receiver end. Specifically, the DSP basis gearbox converts 8 channels of 25GBaud PAM4 signals into 4 channels of 50GBaud (PAM4) signals over an SMF (Singlemode Fiber) cable with duplex LC connectors. This 400G LR4 transceiver product features FEC and full real-time digital diagnostic monitoring, supporting a transmission distance of up to 10km. It defines a 400Gb/s PHY for operation on the four CWDM center wavelengths of 1271, 1291, 1311, and 1331nm. Fiber Mall’s 400G LR4 transceiver has the same function and quality as the Cisco 400G transceiver and Arista 400G transceiver and has better compatibility.

400G QSFP-DD LR4 PAM4 CWDM4 10km LC SMF Optical Transceiver Module with FEC/Fiber Mall

Fiber Mall 400G QSFP-DD LR4  Optical Transceiver

● 400G SR8 Optical Transceiver 

400G SR8 is a Quad Small Form Factor Pluggable–double density fiber optic transceiver compliant to IEEE 802.3bs Specification. This module offers 8 parallel transmitter and receiver lanes, where 400 Gigabit Ethernet signal is carried over. Each of these 8 independent channels is capable of a 53.125Gbps(PAM4) data rate to aggregate a total bandwidth of 400Gb/s on 100 meters of OM3 multi-mode fiber cable with MTP/MPO-16 connector. The center wavelength of the 8 independent channels is 850nm. Similar to DR4, FR4, LR4 QSFP-DD 400G optical module, 400G SR8 is compliant with QSFP-DD MSA specification and IEEE 802.3bs protocol. 

According to the research of Lightcounting, a market research organization in the optical communication industry, on the global optical transceiver market, Fiber Mall will analyze and summarize the global optical transceiver market demand and shipments in 2021.

a pluggable market emerges

Recently, the latest research report of LightCounting shows that the sales of Ethernet optical transceivers will reach US$4.6 billion in 2021, a year-on-year increase of 25%. LightCounting expects the market‘s CAGR(compound annual growth rate)to slow down to 14% in 2022-2027, but even at this modest growth rate, the segment will still reach $10 billion by 2027.

What is driving the growth?

In fact, optical transceiver suppliers have recovered from the impact of COVID-19 in early 2020 in just a few months, with demand for products from 1GbE to 400GbE exceeding their full-year expectations. “As the tide rises, even the sales of 1GbE optical transceivers have picked up, not to mention 10G and 40G products.” Demand for traditional low-rate products began to decline at the end of 2020 but picked up again in the first half of 2021, which was unexpected. Most likely, the new and possibly final wave of demand for traditional low-rate products comes from enterprise and telecom network upgrades, which have been delayed largely due to COVID-19.

Another important factor driving the market growth is the very strong demand for 200GbE and 400G optical modules. Google started deploying 400G optical modules 3 years ago, while Amazon started in 2020, and Meta (formerly Facebook) delayed the deployment of 200G to 2021, which had a huge impact on the market. In addition, the first sale of 2x400G optical modules to Google also contributed to market growth in 2021. This momentum is expected to continue into 2022, but LightCounting predicts slower growth in 2023-2027.

annual growth in sales of Ethernet optical transceivers

LightCounting notes that its forecast model is based on assumptions about bandwidth growth for Ethernet optical connections in numerous applications. Besides, LightCounting has also modeled the consumption of optical modules for each of the top ten cloud computing companies. For example, LightCounting estimates that Amazon will nearly double the bandwidth of its data center network by a massive upgrade to 400G connectivity in 2020 and 2021. Over the longer term, bandwidth growth is expected to decrease to 40% per year, or double every two years or so.

At the same time, LightCounting also raised its expectation for 800G and 1.6T products. LightCounting noted that conservative forecasts are suitable for markets prone to volatility, as it helps explain unexpected slowdowns in demand and economic downturns. It is unusual that the pandemic is good for the optical module industry as a whole. The Ethernet market achieved a CAGR of 18% from 2011 to 2021, without great decline. With that in mind, a CAGR of 14% for 2022-2027 is a very reasonable assumption.

quarterly coherent port shipments

Shipments of 400G ZR/ZR+ modules surged in the fourth quarter of 2021 as Cisco (Acacia) and Marvell rapidly expanded their production capacity, according to research firm Cignal AI’s Q4 2021 Transport Application Report. However, demand from cloud service providers still outstrips supply, which will increase this year as production climbs from suppliers such as Ciena, NeoPhotonics, and II-VI. Cignal AI expects shipments of 400G  ZR/ZR+ modules to grow by 200% in 2022 as cloud operators such as Microsoft, Amazon, and Google, as well as traditional network operators such as AT&T, Windstream, and COLT, roll out large-scale deployments.

Scott Wikinson, the chief optics analyst of Cignal AI, said: “Cloud service providers and telecom operators are making fundamental changes to their network architectures due to the commercial availability of pluggable 400G coherent modules. Shipments of the 400G ZR module are growing rapidly, and so far, more than half of the shipments came from the fourth quarter.”

Further highlights from the Q4 2021 Transport Application Report:

  • As pluggable coherent modules reshape the supplier landscape, the number of coherent ports directly procured by operators is growing rapidly.
  • Shipments of Gen60C pluggable 400G ZR modules still have supply constraints, with only two suppliers meeting nearly all of the demand to date.
  • Ciena remains the largest supplier of state-of-the-art Gen90P 800G coherent ports, although shipments of Infinera and ICE6 products are growing rapidly.
  • Compact modular revenue in North America grew 25% in 2021 and Cienais the market leader in this category.
  • Only Huawei achieved Packet-OTN sales growth in 2021. Nokia’s continued investment in its OTN product portfolio has made it the leading OTN supplier in Europe and the US, where the company is best positioned to win Huawei’s business.

total optical component revenue by company

According to Cignal AI’s latest Optical Components Report, cloud service providers’ capital expenditures for hyperscale data centers drive datacom optical components revenue growth by 27% and the growth reached $4.7 billion in 2021, which outpaced component revenue growth for telecommunication, consumption, and industrial optical applications.

Shipments of modules at this rate doubled to record levels in 2021 as large cloud providers and some enterprise customers’ demand transitioned from 100G to 400GbE. “The transition to 400GbE is well underway, and pluggable coherent 400Gbps technology is revolutionizing the design of optical networks connecting data centers,” said Scott Wilkinson, principal optics analyst at Cignal AI. “The speed of 400Gbps will drive spending and bandwidth growth in and outside the data center in 2022.”

Other highlights of the 4Q21 Optical Components Report:

  • In 2021, shipments of QSFP-DD data communication module were8 million, most of which were in DR4 format;
  • In 2021, more than 60,000 400Gbps pluggable coherent modules were shipped, most of which were QSFP-DD ZR;
  • In 2021, shipments of 200Gbps coherent CFP2 modules increased by 17% to just over 200,000 units, as Chinese OEM Fiber Mall increased capacity at this speed for farther metro and long-haul applications.

As previously known, Cisco finally acquired Acacia at a price of 4.5billion. 

investments in optics, silicon, and software

The growth rate of ordinary optical modules is slowing down, but coherent optical modules doubled. What Acacia does best is exactly the coherent part.

Acacia coherent interfaces and platforms

Dell’Oro’s data shows that 400G ZR will reach 250,000 units in 2026, while 800G ZR will be produced faster than 400G ZR at the very beginning, driving the rapid development of rates.

coherent 400 zr and 800 zr pluggable

The gradually miniaturized coherent module can just meet the concise and open requirements of DCI. Whether it is ZR or ZR+, either 400G or 800G, opportunities for the DCI market outweigh the challenges.

the DCI ecosystem

the DCI challenges


400G transceivers in Quad Small Form-factor Pluggable–Double Density (QSFP-DD) based on the PAM4 modulation technique have become popular for 400G optical network interconnection in the data center. 400G ZR, DR4, FR4, LR4 and SR8 QSFP-DD optical exemplify the PAM4 technology in 400G Ethernet application. Fiber Mall is a professional optical communication integrated supplier, currently providing products including fiber optic transceiver, DAC & AOC cables, fiber optic cables, WDM &PLC splitter, and other networking series. 400G DR4/FR4/LR4/SR8/ZR optical transceivers are available in Fiber Mall and you are always welcome to contact us or visit our website.

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