Dynamic linearity improvement of phase and frequency modulated microwave photonic links using optical lattice filter discriminators

A phase modulated (PM) microwave photonic link (MPL) with linearity improvement is presented. The link demodulates the PM using a phase discriminator based on a dynamically tunable, integrated, sixth-order optical lattice filter in planar lightwave circuit (PLC) technology. The linearity of the demodulation process is optimized by using electrical spectrum monitoring and a feedback algorithm to automatically choose the filter coefficients. For a 2 GHz modulation frequency, the link achieves a 6.7 dB improvement in the third-order output intercept point (OIP3) for intermodulation distortion (IMD) over a Mach-Zehnder interferometer (MZI).