2nd Order Distortion Cancellation in Photonic Time Stretch Analog-to-Digital Converter

We show that the symmetry properties of a dual output push-pull Mach-Zehnder modulator can be exploited for rejection of dispersion induced 2^nd order non-linearities in the time-stretch analog to digital converter. Using differential modulation, followed by signal processing in digital domain, we experimentally demonstrate rejection of harmonic and intermodulation distortions. Simulations predict that non-linear distortion limited dynamic range improves from 34 dB to 57 dB. The approach can also be used for obtaining ultra-wide-band (multi-octave) and high dynamic range analog fiber optic links.