Generalized Heterodyne Interferometry in Kerr Materials

Heterodyne detection, initially developed for radio telecommunications, was adapted to optical frequencies in the 1960s [1]. By mixing a signal with a local oscillator, it enables simultaneous phase and amplitude measurement. It has been widely applied in optical communication, pulse chirp characterization [2], electro-optic modulation [3], and recently for nonlinear phase shift measurements in nanophotonic waveguides [4], [5]. This technique is particularly effective for evaluating the Kerr coefficient, offering enhanced sensitivity and greater simplicity compared to methods like Z-scan or four-wave mixing.