Incoherent pumping-induced optical limiting

The nonlinear optical absorption of a probe field is investigated in a three-level V-type quantum system under a pump-probe configuration. It is demonstrated that the system exhibits saturable absorption (SA) behavior. By introducing an indirect incoherent pumping field on the probe transition, we show that the incoherent field critically influences the switching from SA to reverse saturable absorption (RSA). This switching enables the system to function as an optical limiter, protecting sensors and seekers against high-power optical pulses. The results reveal that key parameters-such as the intensity of the incoherent field, detuning, and coupling field strength-can be precisely tuned to modulate optical limiting characteristics, including threshold intensity and operational range. The underlying physical mechanism is elucidated through the derivation and analysis of an analytical expression for the nonlinear absorption. The output response is further validated through calculations based on the open-aperture Z-scan technique. Overall, this study highlights the crucial role of incoherent field engineering in tailoring optical limiting behavior, providing a versatile framework for advanced photonic applications.