{"id":5131,"date":"2025-09-10T00:00:00","date_gmt":"2025-09-10T00:00:00","guid":{"rendered":"https:\/\/lp.szlogic.cn\/knowledge-center\/qsfp-40g-lr4-long-reach-optical-transceiver\/"},"modified":"2026-05-25T09:45:28","modified_gmt":"2026-05-25T09:45:28","slug":"qsfp-40g-lr4-long-reach-optical-transceiver","status":"publish","type":"post","link":"https:\/\/lp.szlogic.cn\/ru\/knowledge-center\/qsfp-40g-lr4-long-reach-optical-transceiver","title":{"rendered":"QSFP+ 40G LR4 Explained: Your Ultimate Guide to 40G Long-Reach Optics"},"content":{"rendered":"
\"What<\/figure>\n\n\n\n

In the relentless pursuit of faster data centers and enterprise networks, the transition from 10G to 40G Ethernet was a monumental leap. At the heart of this evolution lies a critical component: the QSFP+ 40G LR4 optical transceiver<\/strong><\/a>. This powerful little module is the workhorse for high-bandwidth, long-distance connections. But what exactly is it, and how does it enable such impressive performance?<\/p>\n\n\n\n

This guide will demystify the 40G LR4 QSFP+<\/strong>, exploring its technology, advantages, and how to select the best one for your infrastructure.<\/p>\n\n\n\n

✅ What is a QSFP+ 40G LR4 Module?<\/strong><\/h2>\n\n\n\n

A QSFP+ (Quad Small Form-Factor Pluggable Plus) 40G LR4 is a hot-swappable, compact optical transceiver designed for high-speed network applications. The “40G” denotes its data rate of 40 gigabits per second, while “LR4” stands for Long Reach 4-lane<\/strong>. It’s specifically engineered to transmit data over single-mode fiber (SMF)<\/strong><\/a> for distances up to 10 kilometers.<\/p>\n\n\n\n

Its primary role is to convert 4 channels of 10G electrical signals into 4 optical wavelengths, multiplex them onto a single fiber strand, and do the reverse on the receiving end. This technology is fundamental for data center interconnects <\/strong>(DCI)<\/strong><\/a>, enterprise networking<\/strong>, and telecommunications<\/strong>.<\/p>\n\n\n\n

✅ How Does 40G-LR4 Technology Work? The Magic of WDM<\/strong><\/h2>\n\n\n\n

The secret sauce of the 40G LR4 is Wavelength Division Multiplexing (WDM)<\/strong><\/a>. Instead of using four separate fiber strands, it combines four independent 10G data streams, each carried on a different laser wavelength (1271nm, 1291nm, 1311nm, and 1331nm). These are multiplexed into a single beam of light for transmission.<\/p>\n\n\n\n

On the far end, another 40GBASE-LR4 QSFP+<\/strong> module<\/strong><\/a> receives this beam, demultiplexes it back into the four distinct wavelengths, and converts each back into an electrical signal. This efficient process allows for high bandwidth over a single fiber pair, saving significant infrastructure costs.<\/p>\n\n\n\n

Key Applications and Use Cases<\/strong><\/h4>\n\n\n\n