Circular dichroism (CD) is extensively used in various material systems for applications including biological detection, enantioselective catalysis, and chiral separation. This paper introduces a chiral absorptive metasurface that exhibits a circular polarization-selective effect in dual bands—positive and negative CD peaks at short wavelengths and long wavelengths, respectively. Significantly, we uncover that this phenomenon extends beyond the far-field optical response, as it is also observed in the photothermal effect and the dynamics of thermally induced fluid motion. By carefully engineering the metasurface design, we achieve two distinct CD signals with high g factors (∼1) at the wavelengths of 877 nm and 1045 nm, respectively. The findings presented in this study advance our comprehension of CD and offer promising prospects for enhancing chiral light–matter interactions in the domains of nanophotonics and optofluidics.

The collective response of macroscopic quantum states under perturbation is widely used to study quantum correlations and cooperative properties, such as defect-induced quantum vortices in Bose–Einstein condensates and the non-destructive scattering of impurities in superfluids. Superfluorescence (SF), as a collective effect rooted in dipole–dipole cooperation through virtual photon exchange, leads to the macroscopic dipole moment (MDM) in high-density dipole ensembles. However, the perturbation response of the MDM in SF systems remains unknown. Echo-like behavior is observed in a cooperative exciton ensemble under a controllable perturbation, corresponding to an initial collapse followed by a revival of the MDM. Such a dynamic response could refer to a phase transition between the macroscopic coherence regime and the incoherent classical state on a time scale of 10 ps. The echo-like behavior is absent above 100 K due to the instability of MDM in a strongly dephased exciton ensemble. Experimentally, the MDM response to perturbations is shown to be controlled by the amplitude and injection time of the perturbations.

This paper reports the fabrication of regular large-area laser-induced periodic surface structures (LIPSSs) in indium tin oxide (ITO) films via femtosecond laser direct writing focused by a cylindrical lens. The regular LIPSSs exhibited good properties as nanowires, with a resistivity almost equal to that of the initial ITO film. By changing the laser fluence, the nanowire resistances could be tuned from 15 to 73 kΩ/mm with a consistency of ±10%. Furthermore, the average transmittance of the ITO films with regular LIPSSs in the range of 1200–2000 nm was improved from 21% to 60%. The regular LIPSS is promising for transparent electrodes of nano-optoelectronic devices—particularly in the near-infrared band.

The human visual system, dependent on retinal cells, can be regarded as a complex combination of optical system and nervous system. Artificial retinal system could mimic the sensing and processing function of human eyes. Optically stimulated synaptic devices could serve as the building blocks for artificial retinas and subsequent information transmission system to brain. Herein, photonic synaptic transistors based on polycrystalline MoS₂, which could simulate human visual perception and brain storage, are presented. Moreover, the photodetection range from visible light to near-infrared light of MoS₂ multilayer could extend human eyes’ vision limitation to near-infrared light. Additionally, the photonic synaptic transistor shows an ultrafast speed within 5 μs and ultralow power consumption under optical stimuli about 40 aJ, several orders of magnitude lower than biological synapses (50 ms and 10 fJ). Furthermore, the backgate control could act as emotional modulation of the artificial brain to enhance or suppress memory function, i.e. the intensity of photoresponse. The proposed carrier trapping/detrapping as the main working mechanism is presented for the device. In addition, synaptic functionalities including short synaptic plasticity, long synaptic plasticity and paired-pulse facilitation could be successfully simulated based on the prepared device. Furthermore, the large difference between short synaptic plasticity and long synaptic plasticity reveals the better image pre-processing function of the prepared photonic synapses. The classical Pavlovian conditioning associated with the associative learning is successfully implemented as well. Therefore, the efficient and rich functionalities demonstrate the potential of the MoS₂ synaptic device that integrates sensing-memory-preprocessing capabilities for realizing artificial neural networks with different emotions that mimic human retina and brain.The human visual system, dependent on retinal cells, can be regarded as a complex combination of optical system and nervous system. Artificial retinal system could mimic the sensing and processing function of human eyes. Optically stimulated synaptic devices could serve as the building blocks for artificial retinas and subsequent information transmission system to brain. Herein, photonic synaptic transistors based on polycrystalline MoS₂, which could simulate human visual perception and brain storage, are presented. Moreover, the photodetection range from visible light to near-infrared light of MoS₂ multilayer could extend human eyes’ vision limitation to near-infrared light. Additionally, the photonic synaptic transistor shows an ultrafast speed within 5 μs and ultralow power consumption under optical stimuli about 40 aJ, several orders of magnitude lower than biological synapses (50 ms and 10 fJ). Furthermore, the backgate control could act as emotional modulation of the artificial brain to enhance or suppress memory function, i.e. the intensity of photoresponse. The proposed carrier trapping/detrapping as the main working mechanism is presented for the device. In addition, synaptic functionalities including short synaptic plasticity, long synaptic plasticity and paired-pulse facilitation could be successfully simulated based on the prepared device. Furthermore, the large difference between short synaptic plasticity and long synaptic plasticity reveals the better image pre-processing function of the prepared photonic synapses. The classical Pavlovian conditioning associated with the associative learning is successfully implemented as well. Therefore, the efficient and rich functionalities demonstrate the potential of the MoS₂ synaptic device that integrates sensing-memory-preprocessing capabilities for realizing artificial neural networks with different emotions that mimic human retina and brain.

Broadband absorbers generally consist of plasmonic cavities coupled to metallic resonators separated by a dielectric film, and they are vertically stacking configurations. In this work, we propose an ultra-broadband nanowire metamaterial absorber composed of an array of vertically aligned dielectric nanowires with coaxial metallic rings. The absorber shows strong absorption from 0.2 to 7 μm with an average absorption larger than 91% due to the excitation of gap surface plasmon polariton modes in Fabry–Perot-like resonators. Moreover, a refractory dielectric cladding can be added to improve the thermal stability of the absorber, showing a negligible impact on its absorption performance. The proposed absorber may find potential applications in solar energy harvesting, infrared imaging and spectroscopy, and optoelectronic devices.

Realization of the efficient steering for photons streams from nano sources is essential for further progress in integrated photonic circuits, especially when involving nonlinear sources. In general, steering for nonlinear sources needs additional optical control elements, limiting their application occasions as photonic devices. Here, we propose a simple and efficient beam steering scheme for the second-harmonic (SH) emission in the hybrid waveguide (consisting of CdSe nanobelts on the Au film) by mode-selective excitation. Adjusting the position of the incident beam illuminating on the tapered waveguide, the excitation types of guided modes can be selected, realizing the directionality control of SH emission. Stable steering of 6.1° for the SH emission is observed when the interference modes change from TE00 & TE01 to TE00 & TE02, which is confirmed by SH Fourier imaging and simulations. Our approach gets rid of the complex structural design and provides a new idea for beam steering of nonlinear optical devices with various nonlinear wavefronts.