Determining the magnitude and relative phase of photodiode IMD2 using amplitude matched MZM-distortion cancellation technique

We characterize photodiode-induced second-order intermodulation distortion (IMD2) implementing a new Mach-Zehnder modulator (MZM) distortion cancellation technique. The magnitude and relative phase of photodiode IMD2 can be determined by measurement of an intensity-modulated direct-detection (IMDD) link at the cancellation condition. The magnitude is also found through photodiode fundamental frequency response and calculated second-order output intercept point (OIP2). Experimental results show that the IMDD technique is suitable for rapid amplitude estimation, while also providing phase information for the photodiode non-linearity.