Optical Radiofrequency Signal Mixing by All-Optical Sampling Based on a Semiconductor Optical Amplifier Mach–Zehnder Interferometer

Experimental performances analysis of an optical radiofrequency signal mixer based on a semiconductor optical amplifier Mach-Zehnder Interferometer utilizing an all-optical sampling method is presented. An optical pulse source generating 21-ps width pulses at a repetition rate of 7.8 GHz samples an intensity-modulated optical carrier carrying an electrical subcarrier at the intermediate frequency 1 GHz. The efficiency of the all-optical radiofrequency mixer is evaluated in terms of mixing conversion gain and third-order input intercept point. The conversion gain varies from 14.4 dB to 20.3 dB according to the chosen frequency. In addition, the electrical subcarrier modulated by a Quadrature phase shift keying (QPSK) and a 16-quadrature amplitude modulation (QAM) signal at a data rate of 1 MSymb/s has been frequency up-converted up to 40 GHz with an error vector magnitude of 11.68% for the QPSK modulation and 10.94% for the 16-QAM.