Introduction on 5 Kinds of 40G QSFP+ Optical Transceivers

40G optical transceivers are a series of optical transceivers with 40Gbps transmission rate, in which CFP and QSFP are the main form factors. And the 40G QSFP+ optical transceivers are one of the most widely used optical transceivers. In the post, Gigalight will introduce you several kinds of most popular 40G QSFP+ optical transceivers that can help you have a better choice.


The 40G LR4 QSFP+ optical transceiver is typically used with LC single-mode fiber patch cables for transmission distances up to 10km, and it has 4 data channels that transmit data simultaneously. The advantages of 40G LR4 QSFP+ optical transceivers are high density, low cost, high speed, large capacity, and low power consumption.

The working principle of 40G LR4 QSFP+ optical transceiver: The laser driver controls the arrival wavelength, the optical signal passes through the multiplexer and is combined together for transmission. When arriving at the receiving end, these transmitted signals are then demultiplexed by the demultiplexer into four channels with a transmission rate of 10 Gbps. Then the PIN detector or transimpedance amplifier recovers the data stream and transmits the optical signal.


The 40G SR4 QSFP+ optical transceivers are often used with the MPO/MTP connector in 40G data transmission. It has four independent full-duplex channels and is also transmitted through four channels. The transmission rate is the same as that of the LR4. The difference is that the 40 G SR4 QSFP+ optical transceivers are often used with multimode optical fiber. The transmission distance when using it with the OM3 optical fiber jumper is 100m, and the transmission distance when using it with the OM4 optical fiber jumper is 150m.

The working principle of the 40GBASE-SR4 optical transceiver: when the transmitting end transmits a signal, the electrical signal is first converted into an optical signal via a laser array. When the transmitting end transmits a signal, the photodetector array converts the parallel optical signal when the receiving end receives a signal.


As a highly integrated 4-channel optical transceiver, the 40 G LR4 PSM optical transceivers have the advantages of high port density and low cost. The optical port of this optical transceiver adopts the parallel single-mode technology-PSM. It uses a 4-way parallel design MPO/MTP interface and the transmission distance is 10km.

The work principle of 40 G LR4 PSM optical transceivers is in the same way as the 40 G SR4 QSFP+ optical transceivers. The difference is that 40G LR4 PSM optical transceivers are often used to connect with single-mode ribbon fiber connectors. That is, parallel optical signals are sent in parallel through eight single-mode optical fibers.


The 40G QSFP+DAC high-speed cable consists of two 40G QSFP+ optical transceivers and a copper cable.

DAC Advantages:

(1) Low cost, reducing the impact of dust and other contaminants on optical cables, and improving transmission efficiency;

(2) The high-speed cable is made of copper core, which has good heat dissipation effect and is energy-saving and environmentally friendly.

(3) High-speed cables consume low power.


The 40G QSFP+AOC active optical cable is the core component of the parallel optical interconnection. It is composed of two 40G QSFP+ optical transceivers connected by a ribbon optical cable.

The QSFP+AOC active optical cable is an efficient integrated fiber optic cable assembly designed for short-range, multi-channel data communication and interconnection applications. Each signal direction has four data channels with a rate of 10 Gbps per channel.

 AOC Advantages:

(1) The transmission power is lower, so the power consumption is small;

(2) Weight and volume are much smaller than high-speed cables;

(3) The transmission distance is farther (it can reach 100-300 meters).

In Conclusion

The above five kinds of optical transceivers are available from Gigalight. When you use the optical transceiver purchased in Gigalight, your device’s stability and network speed will be greatly improved. If you want to learn more about optical transceiver solutions, please visit Gigalight official website to view.