40G QSFP+ LX4 VS 40G QSFP+ LR4

1. Introduction

In modern data centers and high-performance networks, 40G optical modules have become an important choice for high-speed transmission. 40G QSFP+ LX4 and 40G QSFP+ LR4 are both common long-haul transmission modules, but they are significantly different in terms of technical implementation, application scenarios and cost. In this article, we will compare these two modules in detail to help you choose the right product according to your actual needs.

2. 40G QSFP+ LX4 VS 40G QSFP+ LR4

2.1. 40G QSFP+ LX4

The 40G QSFP+ LX4 is an optical module that uses wavelength division multiplexing (WDM) technology, which typically uses four different wavelengths of optical signals to transmit data. It is capable of transmitting data over long distances over single-mode fibre. And it is suitable for scenarios where multi-wavelength transmission is required.

• Lunghezza d'onda: The LX4 uses four different wavelengths (typically 1310 nm, 1350 nm, 1390 nm and 1430 nm).

• Fibre Type: Suitable for single-mode fibre, although multi-mode fibre is also supported, but single-mode fibre is more common.

• Maximum Transmission Distance:
• With a maximum transmission distance of up to 10 km, the LX4 is suitable for high-performance transmission across data centres or over long distances. Because it uses WDM technology, the LX4 is suitable for environments that require multi-wavelength signal transmission.

• Signal quality and stability:
• Since the LX4 uses multiple wavelengths for data transmission, it may face problems with signal interference between different wavelengths, thus requiring more precision tuning and higher-quality optical components. The complexity of WDM technology may also result in higher signal quality degradation over very long distances.
• Cost and Performance:
• The LX4 module uses WDM technology, which makes it more expensive to manufacture in some cases. Its multiwavelength implementation also requires more complex technical support. As a result, the LX4 has a higher cost and is suitable for less cost-sensitive applications that require high bandwidth over long distances.

2.2. 40G QSFP+ LR4

40G QSFP+ LR4 is another high-performance long-haul transmission module that uses four different wavelengths of single-mode fiber transmission. The LR4 module is designed to follow the ITU-T G.959.1 standard and uses different optical technologies, such as DML/EML lasers and APD photodetectors, to ensure low attenuation and good signal quality over long distances.

• Lunghezza d'onda: The wavelengths used by LR4 are typically 1264.5-1337.5 nm.

• Fibre Type: Only single mode fibre is supported for long-distance, long-haul transmission.

• Maximum Transmission Distance: The LR4 can reach a maximum transmission distance of up to 10 kilometers. In some cases, it can even reach 20 kilometers. This makes it suitable for Metropolitan Area Networks (MANs) and other long-distance communication needs.

• Signal Quality and Stability: LR4 adopts the more mature four-wavelength splitting technology with relatively small signal attenuation and can maintain higher stability and lower BER over longer distances, especially in data-intensive long-distance communication, the performance of LR4 is superior.

• Cost and Price/Performance: While the LR4 module is also suitable for long-haul transmission, it uses technology that is typically more mature and may be slightly cheaper to manufacture compared to LX4. LR4 is suitable for scenarios where large-scale deployments are required in a cost-effective manner, especially for long-haul connectivity between data centers and across metropolitan areas.

2.3. Selection Guide

• 40G QSFP+ LX4 Scenario:
• suitable for enterprise networks, cloud computing infrastructures, large-scale data centres, etc. that require multi-wavelength transmission and longer distances, especially when it comes to large-scale network deployments across different regions or floors.

• 40G QSFP+ LR4 scenario:
• Suitable for long-distance interconnections in large-scale enterprise and carrier data centres, especially for connectivity applications between metropolitan area networks (MANs) and geographically separated data centres.

3. Conclusion

Whether you choose 40G QSFP+ LX4 or 40G QSFP+ LR4 depends on your network requirements.
For long transmission distances on a budget, LX4 is ideal, offering benefits for specific long-distance and multi-wavelength uses. The 40G QSFP+ LR4, however, strikes a better balance between performance and cost, making it a more economical and mature choice for long-haul data center and metro network connectivity.

Regardless of which module you choose, the decision should be based on the actual application scenario, network topology, and budget to ensure the best performance and price/performance for your network.