The PCMO2128 is a low loss, high integrity polarization multiplexed dual-Cartesian optical modulator (each Cartesian modulator can control the optical intensity and phase to reach any point in the complex plane) based on Gallium Arsenide designed for dual polarization optical phase shift keying over the frequency range DC-25 GHz. The die is fabricated using well proven and exercised high volume gallium arsenide processes used in the telecommunications industry that offers market leading performance optimised for optical applications.