Radio over fiber has attracted much attentions thanks to its capability for low-loss transmission of microwave signal over large bandwidth optical fiber. Generating microwave signal in optical domain can obtain higher-frequency and better-quality signal. It has been considered as the most optimal solution for the distribution of future high-capacity wireless communication. Double-sideband modulation is one of the simplest and most cost-effective approach. However, it suffers from severe periodic power fading which is induced by the fiber chromatic dispersion. Among a large of schemes to overcome this fiber dispersion effect, single sideband (SSB)SSB modulation seems to be the most straightforward technique.
Prof. Junqiang Sun and Phd. Danqi Feng of Wuhan National Laboratory theoretically analyze and experimentally demonstrate a photonic scheme to realize light controlled microwave frequency multiplication and SSB modulation simultaneously. By properly choosing operational parameters of the orthogonal polarized pump light to stimulate the nonlinear birefringent effect in highly nonlinear fiber, the proposed scheme can realize different functions. One is to generate a high frequency microwave signal with a tunable multiplication factor among 1, 2, 4, and 8. The other is to obtain an SSB signal with tunable optical carrier to sideband ratio (OCSR) or simultaneous suppression of the - first and the + second order sidebands. We demonstrate the frequency multiplication function theoretically. A frequency octupled signal at 144 GHz is obtained. The SSB modulation from 10 to 40 GHz with OCSR ranging from −8.7 to 26.7 dB is demonstrated by experiment. The SSB modulation with simultaneous suppression of the - first and + second order sidebands is also observed. The proposed approach operates easily and no wavelength depended device is required. Results show that it has potential applications in improving the transmission of photonic microwave signal processing systems.
On September, 2016, this work “Simultaneous realization of frequency multiplication and single sideband modulation by exploiting nonlinear birefringent effect” was published on IEEE Transaction Microwave Theory and Techniques (Vol. 64, Issue 9, pp. 3010-3016 (2016)). This work is partially supported National Natural Science Foundation of China under Grant 61178002 and Research Fund for the Doctoral Program of High Education of China under Grant 20120142130004.
Fig. 1. Scheme of the proposed system.
Fig. 2. Simulation results of multiplication.
Fig. 3. Experimental results of SSB modulation with tunable OCSR.
Fig. 4. Experimental results of SSB modulation with -1 order and +2 order sidebands suppressed.