OFDM signal down frequency conversion based on a SOA-MZI sampling mixer using differential modulation and switching architectures

A simulation performance analysis of a semiconductor optical amplifier Mach–Zehnder interferometer (SOA-MZI) sampling mixer used as a frequency down converter is presented by employing differential modulation and switching architectures. A clock pulse signal, generating 2 ps-width pulses at a sampling frequency of 13 GHz, is used as a sampling signal. Two optical carriers, intensity-modulated by a sinusoidal signal at 79 and 80 GHz are simultaneously down converted to 1 and 2 GHz, respectively. For the differential modulation architecture, conversion gains of about 34 and 32 dB are demonstrated for the frequency down conversion to 1 and 2 GHz, respectively. Besides, the conversion gain of 20 dB is achieved for down conversion from 79 to 1 GHz for the differential switching architecture. Furthermore, signals modulated by an orthogonal frequency division multiplexing (OFDM) complex modulation format at different bit rates are also down converted from 79 to 1 GHz and from 80 to 2 GHz and their error vector magnitude (EVM) is evaluated and compared. A maximum bit rate of about 8 Gbps satisfying the forward error correction (FEC) limit is fulfilled using differential modulation and switching architectures.