Visual perception is the primary source for humans to acquire information. The mimicking of visual systems is crucial to develop artificial intelligence technologies. Currently, optoelectronic synapses are widely used in artificial visual systems due to the in-memory processing of optical signals. However, the photoelectric conversion of the synapses requires contact processing of input optical signals, which leads to significant energy consumption. In this paper, all-optical artificial synapses were presented based on photochromic perovskite thin films. Under UV and visible light pulse stimulation, the perovskite films exhibit synaptic behaviors in optical transmittance changes, including paired-pulse facilitation and learning ability. Through a recurrent neural network processing the time-dependent transmittance change data, a 100% accuracy in the classification of two digital images can be instantly achieved, even in the first epoch. The all-optical synapses provide an innovative pathway toward energy-friendly artificial visual systems.

Two-dimensional materials have excellent optical properties such as high refractive index and high transmittance. At the same time, when graphene oxide materials are processed by laser, reduction reaction occurs and reduced graphene oxide with graphene-like characteristics is generated, which makes it possible to design Fresnel lenses based on graphene oxide materials. Compared with the traditional optical lens and micro optical lens, this design reduces the lens size from centimeter to nanometer level. In this paper, a Fresnel lens based on graphene oxide film is designed for the working wavelength of 532 nm. The focusing effect of the Fresnel lens is tested by Rayleigh-Sommerfeld diffraction theory and numerical simulation of electromagnetic field. The graphene oxide film is prepared by the drop-casting method with the thickness of about 500 nm, and the Fresnel lens is processed by laser on the film. Finally, the diameter of the focus spot is 2.14 μm, and the focusing efficiency is 41.2%. Compared with the spraying method for preparing graphene oxide films, the drop-casting method for preparing graphene oxide has the advantages of high efficiency and low cost. This design provides the possibility for the integration and large-scale production of nanometer scale graphene oxide based optical systems.

In this paper, a terahertz dual-comb ranging system is constructed based on a fully bias-maintaining erbium-doped fiber laser, phase-locked loop system and terahertz ranging optical path. In the experiment, the full bias-maintaining erbium-doped fiber laser had a repetition frequency of 79.261 MHz, and the repetition frequency was locked and the frequency was adjustable at 1.54 MHz by piezoelectric ceramic (PZT) and stepper motor (SM) dual-stage feedback control scheme. The peak-peak jitter and standard deviation of jitter were ±1.5 mHz and 0.4 mHz respectively. The repetition frequency difference of the dual-comb was set at 10 Hz, and the maximum jitter and standard deviation of repetition frequency difference within 10 min were calculated to be 3 mHz and 0.6 mHz. Furthermore, the asynchronous sampling dual-comb system was applied to the terahertz ranging, and the error of measuring the moving distance was 3 μm. The system has the advantages of high locking precision and strong stability, and is expected to be used in biological nondestructive testing and industrial precision machining.

Rydberg atoms have large polarizabilities and transition dipole moments. They are extremely sensitive to external electric fields. Combining with the quantum interference effect, terahertz fields can be measured with high sensitivity. In this paper, we use a weak DC external electric field to tune the Rydberg state level to Förster resonance, thereby tuning the Rydberg pair interaction from the van der Waals interaction regime to the dipole-dipole interaction regime. This process creates an enhanced blockade effect and then enlarges the corresponding blockade region. The results show that the dipole-dipole interaction-induced blockade region can be 2-3 times larger than that of the van der Waals interaction. According to this characteristic, the external electric field can be used to enhance the blockade effect, which has reference significance for preparing high-quality unidirectional atoms and improving the accuracy of atomic detection in the terahertz-dressed Rydberg transition.

Photodetectors are widely used in communication, detection, medical and other fields. With the development of industries such as aerospace, night vision, remote sensing, thermal imaging, automotive interconnection and consumer electronics, the demand for ultra-wideband photodetectors is increasing. Existing ultrawide band detectors are multiple photodetectors using different materials and different detection bands, which are poorly integrated and restrict the development of the above applications. We design a graphene micron strip-metal grating composite structure photodetector. It provides a photoelectric response in the terahertz, infrared and visible spectral regions. In the visible region, the metal grating significantly increased the detection sensitivity from 1.1 mA/W to 2.5 mA/W. This work provides new ideas for the design of graphene-based ultra-wideband photodetectors.

In order to study the influence of partial etching gratings on the diffracted beam of waveguide gratings and improve the degree of freedom of integrated photonics design, the different structural properties of waveguide partially etched gratings at the edge or middle were analyzed by finite time domain difference method simulation. The input light wavelength is in the range of 1 400～1 700 nm, covering 1 550 nm communication wavelength. The simulation results show that the edge etching method has higher radiation efficiency, lower reflection efficiency, and can control the intensity distribution of the radiated light field. The reflected energy in the intermediate etch method waveguide is stronger and the linewidth is narrower. By using the two etching methods, the larger the grating size, the higher the radiation efficiency. When the grating size is fixed, the larger the waveguide width, the lower the radiation efficiency of edge etching. The partial etching method of waveguide gratings can be used to optimize the design of the integrated optical path.

In this paper, a nanomaterial named ICG/RG108@BSA was designed to encapsulate indocyanine green (ICG) and RG108 using bovine serum protein (BSA). Indocyanine green activated protein Caspase-3 under near infrared laser induction and RG108 up-regulated the expression of GSDME by inhibiting DNA methylation, thus enhancing the pyroptosis of bladder cancer cells caused by Caspase-3 cleavage. ICG/RG108@BSA had excellent biocompatibility, which was effectively phagocytosed by bladder cancer cells. ICG/RG108@BSA produced significant killing effect on bladder cancer cells when activated by 755 nm laser, in which the survival rate of Mb49 was only 6.9% and the survival rate of T24 cells was only 10.7%. The 755 nm laser-excited ICG/RG108@BSA nanomaterial also successfully induced bladder cancer cell pyroptosis, providing a favorable therapeutic condition for tumor immunotherapy of bladder cancer.

In this paper, the effect of fullerene on the holographic properties of photopolymers in the hexafunctional aliphatic polyurethane acrylate/epoxy resin (RJ423/EPIKOTE 828) system was studied, and the influence of fullerene (C60) and exposure light intensity on photopolymers diffraction efficiency were analyzed. The absorption spectrum combined with X-ray diffraction pattern analysis illustrates that the doped fullerene does not chemically reacts with other components in the polymer, and does not impacts on its structure and crystallization properties. Experimental results demonstrate that fullerene doping can effectively increase the rate of monomer polymerization and participate in the diffusion between active monomer molecules. The diffraction efficiency of the photopolymer increases to 86% with the thickness of 200 μm, which the photosensitivity reaches 1.32 cm2/J and the shrinkage rate is reduced by 5 times under the light intensity of 20 mW/cm2 for time of 40～50 s. C60 may enhance the stability of holographic storage, owing to the promotion of polymerization and the suppression of the shrinkage. The comparison of holographic image storage experiments illuminates that the photopolymer doped with fullerene has excellent holographic storage performance, which also shows that fullerene doped photopolymers have great application prospects in the field of holographic storage.

Accurate detection and measurement of magnetic fields, especially extremely weak magnetic fields (below nT level), plays a better auxiliary role in understanding the physical world. With the development of quantum sensing, information, instrumentation and other technologies, atomic magnetic field measurement technology has become the development direction of a new generation of ultra-sensitive magnetic field measurement technology. In this paper, the signal measurement, modulation methods, research progress, design scheme and practical application of atomic magnetometer are summarized. Firstly, the research status of atomic magnetometer at home and abroad in recent years is introduced. Secondly, the basic principle of all-optical atomic magnetometer is discussed. Thirdly, the principle of weak magnetic signal detection is explained in detail and different modulation methods are compared. Finally, the direction of improvement, application fields and challenges of high sensitivity de tection of weak magnetic signal in the future are prospected.

Confocal micro-measurement is a promising technology with non-contact measurement and high-precision displacement recognition capabilities, which is widely used in chip processing, high-precision instrument manufacturing, biomedicine, material chemistry, industrial testing and other fields. The two-dimensional images scanned with high accuracy along the axial position can be used for three-dimensional reconstruction. However, the scanning speed limits the rate of image acquisition. In order to overcome this limitation, researchers have proposed many methods to improve the conventional confocal microscope system. For example, it mainly includes scanning confocal microscope based on scanning galvanometer beam, confocal microscope based on digital micro-mirror device, differential scanning confocal microscope, etc. Here, this paper mainly discusses the working principle, types of objective lens, scanning methods, advantages and disadvantages, and applications of various confocal microscopes. We believe that with the upgrading of the core components of the optical system and the emergence of various accurate and efficient peak algorithms, the scanning speed of the confocal microscope will be faster; the range will be wider and the resolution will be higher in the future.