The development of InGaAs/InP single-photon avalanche photodiodes (SPADs) necessitates the utilization of a two-element diffusion technique to achieve accurate manipulation of the multiplication width and the distribution of its electric field. Regarding the issue of accurately predicting the depth of diffusion in InGaAs/InP SPAD, simulation analysis and device development were carried out, focusing on the dual diffusion behavior of zinc atoms. A formula of Xj=kt-t0+c to quantitatively predict the diffusion depth is obtained by fitting the simulated twice-diffusion depths based on a two-dimensional (2D) model. The 2D impurity morphologies and the one-dimensional impurity profiles for the dual-diffused region are characterized by using scanning electron microscopy and secondary ion mass spectrometry as a function of the diffusion depth, respectively. InGaAs/InP SPAD devices with different dual-diffusion conditions are also fabricated, which show breakdown behaviors well consistent with the simulated results under the same junction geometries. The dark count rate (DCR) of the device decreased as the multiplication width increased, as indicated by the results. DCRs of 2×106, 1×105, 4×104, and 2×104 were achieved at temperatures of 300 K, 273 K, 263 K, and 253 K, respectively, with a bias voltage of 3 V, when the multiplication width was 1.5 μm. These results demonstrate an effective prediction route for accurately controlling the dual-diffused zinc junction geometry in InP-based planar device processing.

Metasurfaces in the long wave infrared (LWIR) spectrum hold great potential for applications in thermal imaging, atmospheric remote sensing, and target identification, among others. In this study, we designed and experimentally demonstrated a 4 mm size, all-silicon metasurface metalens with large depth of focus operational across a broadband range from 9 μm to 11.5 μm. The experimental results confirm effective focusing and imaging capabilities of the metalens in LWIR region, thus paving the way for practical LWIR applications of metalens technology.

Variable optical attenuator (VOA) arrays can be widely applied in optical communication and optoelectronic systems, but few VOA arrays are reported. Here a liquid-stop based microfluidic VOA array is proposed. It uses a spiral orbit to achieve different degrees of synchronous energy attenuation of multiple beams, or uses an annular orbit to achieve a same degree of synchronous energy attenuations, where the clear aperture of liquid stop is regulated by the electrowetting-on-dielectric effect. It has a compact structure, small volume, simple operation and low cost. Meanwhile, the attenuation ratio of beams can be flexibly adjusted to achieve the power equalization. The research results indicate that the VOA array has a wide attenuation range (0-100% attenuation) and very small insertion loss (0.26 dB) over general VOA arrays. The response time is 0.1 ms, and it is insensitive to the polarization. It can also act as an optical switch array. The proposed VOA array demonstrates the potential of integration and high performance, and it can provide a cost-effective way for applications.

Photoreflectance (PR) has been widely used for the characterization of various semiconductors as well as their surface and interface properties due to its non-destructive and high sensitivity virtues. From the viewpoint of the employment of monochromator, the experimental setup may be classified into dark and bright configurations, which were applied to characterize the heterostructure of InP/In0.52Ga0.48As/InP grown by molecular beam epitaxy. It reveals that the front configuration well separates the luminescence from the modulation signal while the backside configuration benefits the extraction of weak modulation signals with the employment of high excitation power. Based on the backside configuration, we also observed a below band-gap excitation phenomenon, i.e. that the modulation signal of InP exhibits under the excitation of energetically low modulation light (1 064 nm laser). The result demonstrates that the backside configuration may be employed as a contactless electro-modulation technique for the characterization of wide band gap semiconductor heterostructures.

As the cell size of uncooled infrared (IR) detectors progressively shrinks, it becomes increasingly important to increase detector absorption. here, an IMIAM (Insulator-Metal-Insulator-Air-Metal) cavity type metasurface uncooled IR detector structure is proposed, which effectively improves the uniformity of the photosensitive layer while enhancing the absorption of the detector. Utilizing systematic simulation and optimization, it has achieved almost perfect absorption in the Long Wavelength Infrared range (8~14 μm), meanwhile, it also shows excellent absorption performance in Mid Wavelength Infrared band. In this paper, the reliability of the structure is also verified by the process. this research may provide alternatives for optimizing conventional uncooled IR detectors

Through sufficient investigation and summary, the development trend and representative work of Metaverse and related technologies in the aerospace field since the 1960s have been sorted out, and it is pointed out that multi-satellite networking, digitalization and virtualization will become important development trends of aerospace science and technology. Hence, a new concept called “Aerospace Metaverse” has been proposed. Based on this concept, the fundamentals of mathematics and physics have been analyzed. Necessry technologies to build Aerospace Metaverse such as digital twins of aerospace and wide domain ultra high speed intelligent perceptionhave been proposed, and their implementation approaches are elaborated. Furthermore, combining with the vigorous development of aerospace technology, scenarios that can be first put into use have been predicted. Several existing difficulties in building Aerospace Metaverse and corresponding solutions have been proposed, providing new ideas for the development of aerospace technology. Finally, an outlook has been made on the future development of Aerospace Metaverse.

In this paper, a dual-band graphene-based frequency selective surface (GFSS) is investigated and the operating mechanism of this GFSS is analyzed. By adjusting the bias voltage to control the graphene chemical potential between 0 eV and 0.5 eV, the GFSS can achieve four working states: dual-band passband, high-pass low-impedance, low-pass high-impedance, and band-stop. Based on this GFSS, a hexagonal radome on a broadband omnidirectional monopole antenna is proposed, which can achieve independent 360° six-beam omnidirectional scanning at 1.08 THz and 1.58 THz dual bands. In addition, while increasing the directionality, the peak gains of the dual bands reach 7.44 dBi and 6.67 dBi, respectively. This work provides a simple method for realizing multi-band terahertz multi-beam reconfigurable antennas.

To meet the high-speed and high-capacity demands of communication, a 300GHz electronic wireless transmission system for terahertz frequencies is proposed, which incorporates Probability Shaping (PS), Discrete Multi-tone Modulation (DMT) and DFT-Spread (DFT-S) techniques. PS increases the Euclidean distance between constellation points, thereby enhancing the receiver sensitivity. In the system at most 55% bit error rate is decreased, enabling to extend transmission range. DFT-S technique reduces 1.68 dB peak-to-average power ratio of Orthogonal Frequency Division Multiplexing (OFDM) signals in the system, thus improving their resistance to nonlinear effects. By integrating these advanced digital signal processing techniques, 12GBaud PS-16QAM OFDM-DMT signals and 10GBaud PS-64QAM DFT-S-OFDM-DMT signals were successfully implemented in 1 m wireless transmission. Finally, the performance advantages of these digital signal processing techniques were compared.

Terahertz (THz) technology is undergoing a rapid development in biomedical applications. Researchers have made a series of important achievements in the study of biological samples on various levels such as biomolecules, cells, tissues, and individual organisms, which provide new insights and innovative approaches for biological research and biomedical diagnosis. In this review, the progress of applying THz technology in biomedical studies has been summarized, including three key aspects, namely, spectroscopic detection, imaging, and biological effects. The challenges encountered in THz biomedical applications have been discussed, and the future development directions have also been envisioned.