All-optical modulation and switching using a nonlinear-optical directional coupler

We present the operational principles and analytical characteristics of several all-optical modulators and switches that incorporate nonlinear directional couplers with either single or double biasing beams. Graphic representation and potential-well models are used effectively to describe the device’s operation and enhance the ability to anticipate its performance. Phase-to-amplitude modulation is considered, which leads to the special case of phase-controlled switching. Amplitude-to-amplitude modulation is studied, which leads to optical amplification phenomena. An intensity-sensitive switch is also examined.