With the increasing demand for 40G Ethernet, many of the current applications of 10G Ethernet are increasingly is unable to meet the needs of data centers for high-density transmission. At the same time, 40G optical modules are being used on a large scale, such as 40GBASE-SR4. This article will introduce some details of the development of 40G optical modules, and will also introduce 40GBASE-SR4 optical modules in detail. Through this article, you can learn more about 40GBASE-SR4.
The implementation of 40Gbit’s system requires a wide range of technologies in the field of electronics and optics. First, it is necessary to multiplex the network service low-speed particles into 40Gbit’s signals, frame them, second, select the suitable format for transmission for encoding, then drive and modulation, and finally, send them to the fiber for transmission to the nearest optical amplification site. Many key technical issues need to be solved to accomplish these tasks, mainly including IC material technology, modulation technology, improving the optical signal-to-noise ratio.
40Gbit/s networks become worse as the pulse width or pulse spacing becomes narrower and the impact of signal jitter and inter-code interference (ISI) on the signal becomes worse. To ensure high-quality waveform transmission, it is necessary to improve digital and analog IC technology for high-speed, wideband, low-noise shaping, and retiming of optical waveforms. In addition, IC function improvement and power consumption reduction is necessary way to reduce costs. Many chips in 40Gbit/s systems require InP (Indium Phosphorus) materials, but InP materials are difficult to fabricate, and the small size of the chips makes coupling with optical fibers non-difficult and large insertion loss.
There are three main types of conventional optical modulators: Distributed Feedback Laser Diode (DFB-LD), Electric Absorption Modulation (EAM, including EAM, integrated on the DFB-LD chip), and LiNbO3 Mach-Zehnder external modulation. The application areas of these modulators are determined by their respective bandwidths, chirp pulses, and wavelength dependence. While the first two are not suitable for high-speed systems, LiNbO3 modulation is considered the best choice for 40Gbit/s WDM transmission systems as it generates high-speed, low-chirp transmission signals with wavelength-independent characteristics. The choice of a 40G modulation format is a challenge. There are various approaches, such as NRZ code, differential phase shift keyed RZ code, optical soliton, pseudo-linear RZ, chirped RZ, full-spectrum RZ, dual binary, etc. From the analysis of the latest research results, differential phase-shift keying RZ codes. DPSK appears to be the most promising. The spectral width of this modulation is between NRZ and RZ, which is more spectrally efficient than ordinary RZ codes, can improve the dispersion tolerance, nonlinear tolerance, and PMD tolerance, and has a longer transmission distance quotient than ordinary RZ codes.
The 40GBASE-SR4 uses NRZ Modulation Format to ensure stable transmission over multimode fiber. The 40GBASE-SR4 is typically used with OM3 or OM4 MMFs, with a maximum transmission distance of 100m on OM3 and 150m on OM4 MMFs. It fully complies with QSFP+ MSA (SFF-8436) protocol. Currently, the 40GBASE-SR4 is arguably the most widely used 40G optical module on the market, bringing 40G high-density transmission to many data centers, and the QSFP+ 40G SR4 optical module operates at 850nm.
With the new technology, the 40GBASE-SR4 optical module achieves very good performance and, in addition, the cost of producing QSFP+ 40G SR4 by third-party manufacturers becomes very low due to the market scale effect. This article introduces the key technology of 40G optical module development, through this article on 40G optical module structure as well as materials, I believe you become more knowledgeable about the 40GBASE-SR4 optical module, if you want to know more about 40GBASE-SR4, you can consult QSFPTEK’s customer service via [email protected]. QSFPTEK is a technology company that specializes in producing high-quality, cost-effective optical modules like 40GBASE-SR4.