With the rapid development of science and technology, optical communication is increasingly widely used in our actual life. And the need for network technology is higher and higher, so that the 100G optical transceivers have been gradually sold on the market. Maybe most of you have already had an overview on what are 100G optical modules, but this post will go deeper into the background, current problems as well as main types of 100G optical transceivers.
1. The Development Background of 100G Optical Transceivers
The earliest developed 100G optical module was developed in 2010, which form factor is CFP. At that time, IEEE launched three standards (SR10, LR4 and ER4) for 100G optical modules, separately focusing on the 100m, 10Km and 40Km transmission. Then the IEEE standard added new 100G SR4 project, but in 2013 it did not reach consensus. By 2016, the 100G optical transceiver modules for various data centers mostly used the 25Gbps Serdes program. And the 100G optical modules that use the 50Gbps Serdes plan slowly appeared.
2. Challenges of 100G Optical Modules
1). Channel Distance: The DWDM system supporting the 50GHz wavelength distance is very extensive. The 100G optical module needs to be satisfied with the condition of supporting the 50GHz wavelength distance, therefore, the pattern of high spectral power should be used.
2). OSNR (optical signal-to-noise ratio): Under the same pattern, 100G optical module requires 10dB higher than 10G optical module and 4dB higher than 40G optical modules. Therefore, a low OSNR tolerance code and high coding gain FEC algorithm.
3). CD margin: Under the same conditions, the dispersion tolerance for 100G optical modules is 1/100 of 10G optical modules, accounting for 40G optical module 16/100. It can use dispersion compensation technology, in the electric field or the optical domain compensation to complete the dispersion compensation for each wavelength.
4). PMD tolerance: Under the same conditions, PMD (polarization mode dispersion) tolerance of 100G optical modules is 1/10 of 10G optical module, accounting for 4/10 of 40G optical module, so you need to choose coherent reception and digital signal processing.
5). Non-linear effects: 100G optical module than 10G / 40G optical module nonlinear effects more messy.
3. Main Types of 100G Optical Transceivers
According to the different form factors, 100G optical modules mainly include the several types: CFP / CFP2 / CFP4, CXP and QSFP28. Among all of them, CFP / CFP2 / CFP4 and CXP are form factors of early 100G optical modules and QSFP28 are new generation of form factor for 100G optical modules.
With the advantages of high port density, low power consumption & cost and so on, it has gradually become the mainstream 100G optical module form factor. There are four main types of 100G QSFP28 optical transceivers, including 100G QSFP28 SR4, 100G QSFP28 LR4, 100G QSFP28 PSM4, and 100G QSFP28 CWDM4. The principle of the 100G QSFP28 optical module is similar to that of the 40G QSFP + optical module. The 100G optical signal is transmitted in 4 × 25 Gbps mode.
All of the 100G optical transceivers can be founded in Gigalight. It focuses on the development of optical communication products, not only many types of 100G optical modules, but also in accordance with the requirements of users to customize the 100G optical modules with satisfactory conditions.