Interfacial Charge-Transfer-Enhanced Reverse Saturable Absorption for Superior Optical Limiting in MoS2–MoO3 Heterostructure under Nanosecond Laser Pulses

Abstract

The development of efficient optical limiters remains a challenge for protection against intense laser radiation. Heterostructures have unrealized potential as efficient optical limiters, but their systematic study is limited. In this work, a heterostructure comprising MoS2 nanosheet and MoO3 nanorod is synthesized, and the optical limiting performance is systematically analyzed using an open-aperture z-scan setup under nanosecond laser pulse excitation. Structural analyses confirmed the formation of a heterostructure facilitating electron transfer. The optical studies highlight a broadband absorption of the heterostructure with an effective bandgap of 1.6 eV. The heterostructure exhibits a remarkable two-photon absorption coefficient, which is a 2-fold enhancement over MoS2 nanosheets and MoO3 nanorods. This synergistic enhancement is due to charge transfer dynamics and the creation of new intermediate states that facilitate two photon absorption (TPA). Significantly, the heterostructure shows an effective optical limiting threshold of 1.76 × 1012 W/m2, highlighting its superior capability to attenuate intense pulsed radiations at low intensities. These findings establish heterostructure engineering as an innovative strategy for developing next-generation optical limiting materials for photonic protection devices, laser safety applications, and nonlinear optical technologies.