OREANDA-NEWS. Fujitsu Laboratories Ltd. and the Fraunhofer Heinrich Hertz Institute HHI today announced the development of a new method to simultaneously convert the wavelengths of wavelength-division-multiplexed signals necessary for optical communication relay nodes in future wavelength-division-multiplexed optical networks, and have successfully tested the method using high-bandwidth signal transmission in the range of 1 Tbps.

In the conventional optical wavelength conversion method each individual optical wavelength is converted into an electrical signal and re-transmitted at a new wavelength, which is impractical for terabit-class processing as each wavelength requires its own O/E/O circuit. Using the new technology, the optical wavelength conversion and the polarization state are controlled at the same time, so simultaneous wavelength conversion of wide-band optical signals can be achieved without restrictions on the wavelengths of the optical input signal or the modulation formats. As a result, processing can be achieved with a single wavelength converter, regardless of the number of wavelengths multiplexed. Therefore, considering optical signals in excess of 1 Tbps multiplexed from ten wavelengths, for example, the new method can process them using just one-tenth of the power or less compared to previous technologies that required a separate circuit to convert each wavelength into an electrical signal and back.

By applying this technology to the optical nodes within the optical network, the usage efficiency of the communications band is improved, and this is expected to contribute to a more stable communications environment.

Details of this technology will be announced at ECOC 2016 (42nd European Conference on Optical Communication), an international conference that will be held from Sunday, September 18 to Thursday, September 22 in Dusseldorf, Germany.

Today, optical fiber networks which support large-scale datacenters and sophisticated cloud-based ICT services rely on wavelength-division-multiplexing (WDM) technology, which combines optical signals of different wavelengths for transmission in a single optical fiber to connect multiple terminals in an optical network with high bandwidth and low latency. In recent years, the bandwidth achieved per wavelength typically is 100 Gbps with the polarization-multiplexed quadrature phase shift keying modulation method. Progress is now being made on developing technology that, by increasing the modulation multiplicity, will make it possible to achieve terabit-class high-bandwidth communications environments in the future.

Now Fujitsu Laboratories and Fraunhofer HHI have discovered a new simultaneous wavelength conversion method that controls the optical wavelength conversion and the polarization state at once, and have created a prototype wavelength conversion circuit based on this principle. Using this prototype circuit, they succeeded in an experiment to simultaneously convert optical polarization division multiplexed optical signals exceeding 1 Tbps. This represents the world's first successful implementation of a simultaneous wavelength conversion capability that functions without any restrictions on the wavelength of the optical signals input or the modulation format.