Precise broadband characterization of optoelectronic devices using optical two-tone signal-based second- and third-order nonlinearity measurements

The nonlinearity of optoelectronic devices is critical in broadband systems due to harmonic and intermodulation interference. This study proposes a method to evaluate second- and third-order nonlinearities in photodetectors using optical two-tone signals with wide frequency separation. Two models address frequency-dependent effects, with corrections for accurate measurement. Experiments with amplifiers and passive components validated the approach. The method enables reliable performance evaluation of optical devices, contributing to low-distortion, high-speed optical communication systems.