Modeling and optimization of low chirp LiNbO3 Mach-Zehnder modulators with an inverted ferroelectric domain section

Domain inversion under coplanar waveguide electrodes is proposed to improve the frequency-chirping behavior of Z-cut LiNbO3 Mach-Zehnder modulators. This is achieved by introducing a phase reversal electrode section in tandem with inverted ferroelectric domains. The method opens the way to broad-band single-drive modulators with predetermined chirp parameter. The experimental results obtained at 10 Gb/s confirm the possibility of lowering the chirp parameter of a Z-cut modulator, while keeping a halfwave voltage lower than 5 V.