Control of the optical carrier to sideband ratio in optical double/single sideband modulation by the phase variation of RF signals

We propose and experimentally demonstrate a novel approach to realize tunable optical carrier-to-sideband ratio (OCSR) by introducing two radiofrequency (RF) signals with phase difference to drive a Mach-Zehnder modulator. Stimulated Brillouin scattering is adopted to remove the undesirable sideband, converting double sideband (DSB) to single sideband (SSB). By altering RF signal phase difference, wide ranges of OCSR from −23 to 44 dB and −21 to 44 dB are obtained for the DSB and SSB modulation, respectively. The operation frequency bandwidth covers from 5 to 42.3 GHz. The optimum OCSR to maximize the output RF power is also presented for the best transmission behavior. The proposed approach will be vital for optimizing the transmission performance by improving modulation efficiency and receiver sensitivity.