With the emergence of a variety of network applications, such as HD-TV, video sharing, andcloud computing, the end-users’ demands for bandwidth increase dramatically.In the long-haulnetworks, coherent detection for 100-Gb/s transmission has achieved great success due to thesophisticated opticalcomponents and powerful digital signal processing (DSP). Now,medium and short reach networks, such as data center interconnection with the capacity of40-Gb/s and beyond over hundreds of kilometers are strongly desired.
Professor Wei Li, Dr. Yiqin Chen with the Wuhan National Lab for Optoelectronics, Huazhong University of Science and Technology and Dr. Rong Hu, Dr. Shaohua Yu, Professor Qi Yang with the State Key Laboratory of Optical Communication Technologies and Networks proposed a novel fading-free direct-detection opticalorthogonal frequency division multiplexing (DDO-OFDM) scheme for100-Gb/s medium-reach transmission.
In the proposed scheme, two bands spaced at 100-GHz is adopted to accommodate the same complex-valuedOFDM signal. However, the signals are coupled with a pair of orthogonaloptical carriers. By doing so, real and imaginary parts of the complex-valuedOFDM signal can be recovered from the two bands, respectively. We alsopropose a cost-effective scheme to generate such DDO-OFDM signal usingan optical 90-degree hybrid and an optical I/Q modulator. The advantage ofthe proposed method is that it is fadingfree, and the electrical spectralefficiency (SE) is doubled compared to traditional direct-detection method.Finally, researchers experimentally demonstrated a 101-Gb/s dual-band transmissionover 320-km SSMF within only 30-GHz electrical bandwidth, which ishighly competitive in both capacity and cost.
The paper was published at Optics Express (Vol. 23, No. 9, pp. 12065–12071, 2015) and this work was jointly supported by the National Natural Science Foundation of China (GrantNo. 61307083), and the Major Science Innovation Project of Hubei Province (GrantNo.2014AAA001).