本工作应用截面扫描隧道显微镜（XSTM）研究了分子束外延生长的Hg_0.72Cd_0.28Te薄膜。扫描隧道谱（STS）测量显示，此碲镉汞材料的电流-电压（I/V）隧道谱呈现的零电流平台宽度（隧道谱表观带隙）比其实际材料带隙增大约130%，说明存在明显的针尖诱导能带弯曲（TIBB）效应。应用扫描隧道谱三维TIBB模型计算发现低成像偏压测量时获取的I/V隧道谱数据与理论计算结果有令人满意的一致性。然而较大成像偏压时所计算的I/V谱与实验谱线在较大正偏压区域存在一定偏离。这是由于目前的TIBB模型未考虑带带隧穿，缺陷辅助隧穿等碲镉汞本身的输运机制对隧道电流的影响造成的。

本文基于0.1-μm砷化镓赝配高电子迁移率晶体管（GaAs pHEMT）工艺，研制了一款覆盖整个W波段的宽带低噪声放大器。提出了一种由双并联电容组成的旁路电路，能够提供宽带射频接地，减小了级间串扰，利于实现宽带匹配。采用双谐振匹配网络实现了宽带的输入匹配和最佳噪声匹配。实测结果显示，最大增益在108 GHz处达到20.4 dB，在66~112.5 GHz范围内，小信号增益为16.9~20.4 dB。在90 GHz处，实测噪声系数为3.9 dB。实测的输入1-dB压缩点在整个W波段内约为-12 dBm。

We propose a neural network equalization delta-sigma modulation (DSM) technique. After performing DSM on the multi-order quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) signal at the transmitting end, neural network equalizer technology is used in the digital signal processing at receiving end. Applying this technology to a 4.6 km W-band millimeter wave system, it is possible to achieve a 1 Gbaud 8192-QAM OFDM signal transmission. The data rate reached 23.4 Gbit/s with the bit error rate at 3.8 × 10^-2, lower than soft-decision forward-error correction threshold (4 × 10^-2).

Excitons have significant impacts on the properties of semiconductors. They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping. Huybrecht variational method is also found to influence the study of exciton ground state energy and ground state binding energy in Al_xGa_1?xAs semiconductor spherical quantum dots. The Al_xGa_1?xAs is considered to be a direct semiconductor at Al concentration below 0.45, and an indirect one at the concentration above 0.45. With regards to the former, the ground state binding energy increases and decreases with Al concentration and eigenfrequency, respectively; however, while the ground state energy increases with Al concentration, it is marginally influenced by eigenfrequency. On the other hand, considering the latter, while the ground state binding energy increases with Al concentration, it decreases with eigenfrequency; nevertheless, the ground state energy increases both with Al concentration and eigenfrequency. Hence, for the better practical performance of the semiconductors, the properties of the excitons are suggested to vary by adjusting Al concentration and eigenfrequency

A new theoretical method to study super-multiperiod superlattices has been developed. The method combines the precision of the 8-band kp-method with the flexibility of the shooting method and the Monte Carlo approach. This method was applied to examine the finest quality samples of super-multiperiod Al_0.3Ga_0.7As/GaAs superlattices grown by molecular beam epitaxy. The express photoreflectance spectroscopy method was utilized to validate the proposed theoretical method. For the first time, the accurate theoretical analysis of the energy band diagram of super-multiperiod superlattices with experimental verification has been conducted. The proposed approach highly accurately determines transition peak positions and enables the calculation of the energy band diagram, transition energies, relaxation rates, and gain estimation. It has achieved a remarkably low 5% error compared to the commonly used method, which typically results in a 25% error, and allowed to recover the superlattice parameters. The retrieved intrinsic parameters of the samples aligned with XRD data and growth parameters. The proposed method also accurately predicted the escape of the second energy level for quantum well thicknesses less than 5 nm, as was observed in photoreflectance experiments. The new designs of THz light-emitting devices operating at room temperature were suggested by the developed method.

This paper experimentally demonstrates a distributed photonics-based W-band integrated sensing and communication (ISAC) system, in which radar sensing can aid the communication links in alignment and data rate estimation. As a proof-of-concept, the ISAC system locates the users, guides the alignment, and sets a communication link with the estimated highest data rate. A peak net data rate of 68.6 Gbit/s and a target sensing with a less-than-1-cm error and a sub-2-cm resolution have been tested over a 10-km fiber and a 1.15-m free space transmission in the photonics-based W-band ISAC system. The achievable net data rates of the users at different locations estimated by sensing are experimentally verified.

针对现有多波段成像系统体积大、功耗高和集成化设计困难的问题，本文提出了一种基于单传感器的三波段共口径成像光学系统的设计方法。首先，在光学系统的光阑处设计1×2多波段透镜阵列，把可见光波段和短波红外波段同时成像在一个像平面上，并把两个波段中心波长的成像位置偏差控制在一个像元内以实现双波段融合成像。然后，针对双波段成像衍射极限不同的问题，提出分通道透镜阵列的离轴偏移量和通光口径大小联合优化方法，并采用双电动光阑高速控制三个成像通道的切换速度。最后，设计了一个基于单传感器的焦距为30 mm，工作波段分别为480~900 nm、900~1700 nm和480~1700 nm的三波段共口径光学系统。设计及分析结果表明该系统具有成像质量好、结构紧凑、无运动光学元件、成像波段切换速度快等优点。

光学频率梳（简称光频梳）作为一种优秀的多波长光源在通信领域具有巨大的应用潜力。通过将光频梳光源与波分复用技术（WDM）、空分复用技术结合（SDM），通信系统可以具有百Tbit/s量级的传输速率，在5G/6G通信、物联网、自动驾驶等方面具有重要的应用价值。目前实现光频梳的方法主要有以下四种，分别为基于锁模激光器产生飞秒光频梳、基于光学微腔产生光频梳、基于电光调制器产生光频梳以及基于行波四波混频产生光频梳。它们各具特点，但均很难同时实现宽光谱、高信噪比、高平坦度、高的单梳齿功率以及梳齿频率间隔大范围可调，这在一定程度上影响了光频梳在光通信领域的应用。本文提出基于受激布里渊激光腔产生种子梳，采用腔外负色散光纤进行脉冲压缩，进一步利用色散调控的高非线性氟碲酸盐光纤进行扩谱，从而实现光频梳产生。数值计算结果表明，通过该系统，我们可以得到重复频率大范围可调、光谱覆盖整个O-U波段且在O-U波段梳齿强度标准差小于5 dB的平坦光频梳，证明了通过基于布里渊激光腔与色散调控高非线性氟碲酸盐光纤的光学系统产生可用于光通信的平坦光频梳的可行性。