Dual-Wavelength Linearization of Optically Phase-Modulated Analog Microwave Signals

We demonstrate a new technique for improving the linearity of a microwave photonic signal transmission link. The method employs a single conventional lithium-niobate phase modulator at the transmitter, with two different C-band optical wavelengths that are polarized along orthogonal axes of the modulator. The spurious-free dynamic range is shown to improve by 15 dB compared to a single-wavelength unlinearized system. Unlike earlier schemes that require continuous control and adjustment at the transmitter in order to maintain linearity, the new method enables all of the linearization to be controlled at the receiver end.