In the deployment of 40G networks, the 40G QSFP+ optical module is one of the most widely used, defined by IEEE 802.3ba, and supports different applications. The two basic interface specifications for QSFP+ optical modules are 40G BASE-SR4 and 40G BASE-LR4. In this blog, ETU-LINK will talk about the differences between 40 QSFP+ SR4 optical modules and 40G QSFP+ LR4 optical modules. Let's take a look together!

Firstly, both the 40G QSFP+ SR4 optical module and the 40G QSFP+ LR4 optical module are four channel full duplex transceiver integrated modules with a speed of 40G. Their operating temperatures comply with commercial grade (0-70 ℃) temperature standards and both have digital diagnostic and monitoring DDM functions, which is their similarity. Next, we will mainly analyze their differences, mainly from the aspects of center wavelength, fiber type, connector, transmission distance, power consumption, working principle, application, etc.

The central wavelength is different. The wavelength of the 40G QSFP+ SR4 optical module is 4x850nm, while the 40G QSFP+ LR4 optical module adopts CWDM coarse wavelength division multiplexing technology, with four wavelengths of 1271nm, 1291nm, 1311nm, and 1331nm.

The fiber type and connector are different. The 40G QSFP+ SR4 optical module is generally used with multimode fiber jumpers and uses MPO connectors. The 40G QSFP+ LR4 optical module is used in conjunction with single-mode fiber optic jumpers, using duplex LC connectors.

The transmission distance is different. The 40G QSFP+ SR4 optical module supports link lengths of 100M and 150M respectively on OM3 and OM4/OM5 multimode fibers with MPO connectors. The 40G QSFP+ LR4 optical module supports a link length of 10KM on OS2 single mode fiber with duplex LC connectors.

Different power consumption. The 40G QSFP+ SR4 optical module supports a minimum power consumption of less than 1.5W, while the 40G QSFP+ LR4 optical module supports a minimum power consumption of less than 2.5W.

The working principle is different. The working principle of the 40G QSFP+ SR4 optical module is that the electrical signal is first converted into an optical signal through a laser array, and the photodetector array converts the parallel optical signal into a parallel electrical signal. The working principle of the 40G QSFP+ LR4 optical module is: the laser driver controls the wavelength of arrival, and the optical signal is combined and transmitted together through a multiplexer. When it reaches the receiving end, these transmitted signals are decomposed into four channels with a transmission rate of 10Gbps by a demultiplexer. Then, the PIN detector or mutual resistance amplifier recovers the data flow and transmits the optical signal.

Different applications. The 40G QSFP+ SR4 optical module is commonly used in multimode applications, and can be connected between two 40G network devices using MPO fiber optic jumpers. It can also be used with MPO-LC fiber optic branch jumpers to connect between 40G network devices and 10G network devices. 40G QSFP+ LR4 optical modules are commonly used in single mode applications to achieve medium to long distance connections between data center network devices.

The 40G QSFP+optical modules provided by ETU-LINK are widely compatible with major switch brands such as Huawei, Cisco, H3C, ZTE, Ruijie, Zhanbo, Dell, IBM, Inter, etc. You can choose with confidence! For more information, welcome to visit ETU-LINK's website. That's all for this article. Thank you for your support!