Fujitsu collaborates to research and develop multi band wavelength fiber optic transmission technology

Recently, Fujitsu and KDDI research company have successfully developed a high-capacity multi band wavelength multiplexing transmission technology using installed optical fibers.
The new technology of the two companies can transmit wavelengths beyond the C-band by using batch wavelength conversion and multi band amplification technology.

Expanding transmission capacity in remote areas
Two companies have stated that fiber optic communication networks using this technology can achieve wavelength transmission, with a wavelength transmission factor 5.2 times that of current commercial optical transmission technologies.

In this way, the installed fiber optic facilities can be utilized to increase communication traffic in a cost-effective and labor-intensive manner. This technology can also more easily expand the transmission capacity of cities and densely populated residential areas, which may be challenging to install and offer the potential to reduce the time required to initiate services and lower costs.

This development is part of the "Research and Development Project for Enhanced Infrastructure of Post 5G Information and Communication Systems" commissioned by the Japan New Energy and Industrial Technology Development Organization (NEDO).

Figure 1: System image using high-capacity multi band wavelength multiplexing transmission technology (Image source: Fujitsu)

NEDO aims to strengthen the development and manufacturing foundation of Japan's post 5G information and communication systems by developing core technologies. Therefore, from October 2020 to October 2023, Fujitsu and KDDI Research Company participated in a project to improve the performance of the next generation 5G optical network. Traditional commercial fiber optic communication networks use single-mode fibers, where light only passes through the center of the fiber and uses the C-band as the signal transmission band of the optical network. However, with the increase in communication traffic, it is expected that the transmission capacity of only the C-band will be insufficient. In order to increase the transmission capacity of each fiber, the two companies aim to increase the wavelength used from the C-band to the L-band, S-band, U-band, and O-band, in order to achieve multi band transmission.

Potential outcomes of optical communication
As part of this project, Fujitsu has established a simulation model that considers the degradation factors of transmission performance in multi band transmission, thus achieving the transmission design of multi band wavelength multiplexing systems. The simulation model reflects the measurement results of commercial optical fiber characteristics and verifies the extracted transmission parameters through an experimental system integrating a wavelength converter/multi band amplifier.

By using this model, Fujitsu has achieved high-precision simulation, reducing the actual measurement error to within 1dB, thus taking into account the interaction between frequency bands and the degradation of transmission performance.

The research of KDDI Institute has made it possible to use twice the frequency bandwidth of traditional C-band in the O-band, which has never been used before in high-density wavelength division multiplexing (DWDM) transmission.

Combining these two technologies, the two companies conducted actual transmission experiments using existing optical fibers and demonstrated multi band wavelength multiplexing transmission in the O, S, C, L, and U frequency bands (transmission distance of 45 kilometers), proving that the possibility of wavelength transmission is 5.2 times higher than the wavelength multiplexing rate of traditional C-band transmission. The two companies have also confirmed the multi band wavelength multiplexing transmission (transmission distance of 560 kilometers) in the S, C, L, and U bands during simulation.

In this project, Fujitsu and KDDI Research established a design method for a multi band wavelength multiplexing system by constructing a simulation model that considers the interaction between different frequency bands and transmission performance degradation factors.

In addition, since the WDM optical signals in the S-band and U-band are respectively generated by the C-band and L-band optical signals through all optical signal processing technology, there is no need to use dedicated transmitters and receivers in the S-band and U-band.

The integration of these technologies enables DWDM transmission in the S-band+C-band+L-band+U-band using coherent transmission technology, utilizing the phase of light to achieve high-speed and high-capacity communication.

This method minimizes the impact of nonlinear noise to the greatest extent possible, thus overcoming the challenges associated with coherent transmission technology and causing distortion of the O-band transmission signal. By omitting signal compensation at the transmitting end and wavelength dispersion compensation at the receiving end, coherent DWDM transmission in the O-band above 9.6 THz was achieved. The O-band is less affected by wavelength dispersion and has the advantages of reducing digital signal processing load and improving energy efficiency.

Source: OFweek Laser Network