The passive Q-switching characteristics of a diode-pumped Tm,Ho:YAP laser at 2 μm based on a MoS ₂ saturable absorber (SA) is presented for the first time. Pulses as short as 435 ns under a repetition rate of about 55 kHz were generated at the incident pump power of 8.4 W, corresponding to the pulse peak power up to 11.3 W. This is, to the best of our knowledge, the highest pulse peak power, ever obtained from MoS ₂ based passively Q-switched 2-μm lasers. The experimental results sufficiently validated the feasibility of MoS ₂ as SA for solid-state 2-μm lasers.

We investigate the saturable absorption properties of Bi₂Se₃ in a bulk laser operating at 2 µm wavelength region. The Bi₂Se₃ saturable absorber (SA) is prepared with the liquid-phase exfoliation method, which gives a saturable input flux of 4.3 mJ/cm², a modulation depth of ∼10%, and a non-saturable absorption of 10.2%. With the Bi₂Se₃ saturable absorber, a passive Q-witching Tm:YAG ceramic laser is realized with a shortest pulse duration of 355 ns, a single pulse energy of 6.76 µJ and peak power of 19 W. We believe that this is the first report on Bi₂Se₃ Q-switched 2 µm bulk laser.

Memristors are regarded as promising candidates for breaking the problems including high off‐chip memory access delays and the hash rate cost of frequent data moving induced by algorithms for data‐intensive applications of existing computational systems. Recently, organic–inorganic halide perovskites (OIHPs) have been recognized as exceptionally favorable materials for memristors due to ease of preparation, excellent electrical conductivity, and structural flexibility. However, research on OIHP‐based memristors focuses on modulating resistive switching (RS) performance through electric fields, resulting in difficulties in moving away from complex external circuits and wire connections. Here, a multilayer memristor has been constructed with eutectic gallium and indium (EGaIn)/ MAPbI₃/poly(3,4‐ethylenedioxythiophene): poly(4‐styrenesulphonate) (PEDOT: PSS)/indium tin oxide (ITO) structure, which exhibits reproducible and reliable bipolar RS with low SET/RESET voltages, stable endurance, ultrahigh average ON/OFF ratio, and excellent retention. Importantly, based on ion migration activated by sound‐driven piezoelectric effects, the device exhibits a stable acoustic response with an average ON/OFF ratio greater than 10³, thus realizing non‐contact, multi‐signal, and far‐field control in RS modulation. This study provides a single‐structure multifunctional memristor as an integrated architecture for sensing, data storage, and computing.

Deep neural networks based on physical information are expected to be effective alternatives to numerical electromagnetic solvers because they can efficiently solve Maxwell’s equations and obtain the nonlinear physical relationship between the device geometry and its output fields. In this article, we propose a mesh-free and unsupervised time-domain MaxwellNet as a forward model for time-domain electromagnetic simulations, which is qualified to predict the electromagnetic fields of inhomogeneous media of different materials with similar settings in a single inference. We use this network to predict the time-domain electromagnetic fields of several structures with different geometries and achieve good results. Furthermore, experiments show that the model has good generalization ability in both the time and problem-solving range. Finally, we treat the trained model as a Maxwell solver and use it for the inverse design problem. Numerical results show the effectiveness of time-domain MaxwellNet in solving both forward and inverse problems.

Strong magneto-optical effect with low external magnetic field is of great importance to achieve high-performance isolators in modern optics. Here, we experimentally demonstrate a significant enhancement of the magneto-optical effect and nonreciprocal chiral transmission in low-biased gyrotropic media. A designer magneto-optical metasurface consists of a gyrotropy-near-zero slab doped with magnetic resonant inclusions. The immersed magnetic dopants enable efficient nonreciprocal light–matter interactions at the subwavelength scale, providing a giant macroscopic nonreciprocity and strong robustness against the bias disturbance. Microwave measurements reveal that the metasurface can act as a chiral isolator for circular polarization, with extremely weak intrinsic gyromagnetic activity. We also demonstrate its capability of signal isolation for circularly polarized antennas. Our findings provide an experimental verification of nonreciprocal photonic doping with low static magnetic fields.

Chiral metamirror is one of the recently developed metadevices which can reflect designated circularly polarized waves, mimicking the exoskeleton of iridescent green beetles. Here, an optically transparent metamirror that can absorb microwave chiral photons in a broadband spectrum is demonstrated. A coupled mode theory is adopted to reveal the underlying physics for the improved bandwidth performance. Excellent agreements have been observed between numerical and experimental results, indicating a bandwidth for chiral absorption as high as 2.37 GHz. The optical transparence of the resistive patterns and substrate make the designed metamirrors suitable as microwave coatings in front of optical devices, which may find potential applications in cascaded optical systems working for both microwave and optical signals.