Microwave gain-assisted optical limiter in molecular magnets.

Abstract

We investigate the optical properties of a crystal of molecular magnets within the microwave frequency range. It is shown that in the presence of a static magnetic field and applying a coupling laser field in the microwave region, reverse saturable absorption in the microwave domain can be induced in molecular magnets. Notably, the intensity and detuning of the coupling laser field are shown to exert significant control over electromagnetically induced optical limiting (OL). Thus, the OL behavior can safeguard the active sensors in seekers against the saturation as they approach microwave sources. What we believe to be a novel optical limiting phenomenon is introduced, wherein the crystal amplifies noiselessly weak input microwave fields in the linear region of the optical limiter while attenuating intense input fields. Consequently, these findings suggest the potential for actively controlling radars or seekers by exploiting a gain-assisted optical limiter to detect microwave sources with weak signals. The static magnetic field, acting as a pivotal parameter, significantly influences the attainment of OL performance across a broad spectrum of microwave frequencies. We anticipate that the outcomes of this investigation could be applied in microwave photonics to enhance the ranging capabilities of missile seekers or radars via the identification of weak signal targets. Additionally, the research highlights the protective capabilities of microwave sensors against high-power microwave signals. Finally, the open aperture Z-scan technique is employed to confirm the induced gain-assisted optical limiting behavior in molecular magnets.