Differential drive I/Q modulator based on silicon photonic electro-absorption modulators

We demonstrate up to 100Gbaud quadrature- amplitude modulated(QAM) signal generation with monolithic silicon in-phase quadrature(I/Q)-modulator based on silicon-germanium (SiGe) electro-absorption modulators (EAM). The modulator is in a differentially driven Mach-Zehnder(MZ) interferometric configuration similar to the conventional MZ modulator (MZM) based (I/Q) modulators. In particular, single-polarization quadrature phase-shift keying(SP-QPSK) signaling at symbol rates of 100 Gbaud with BERs below the hard-decision forward error correction (FEC) limit is shown. SP-QPSK optical signal generation and transmission over 80km single-mode fiber(SMF) are demonstrated at symbol rates of 50Gbaud with BER of less than ${10^{-5}}$. The effect of the frequency roll-off used for Nyquist pulse shaping with raised cosine frequency response is studied for SP-QPSK 50 Gbaud signals. Furthermore, 16QAM signals at symbol rates of 50 Gbaud are generated.