海洋立体结构信息是未来实现海洋透明与海洋强国的基础，针对海洋剖面探测能力不足的问题，以及星载海洋剖面多要素同源同域一体化探测空白，开展星载海洋剖面多要素探测技术与系统方案研究，提出新型激光主被动复合、能谱复用探测技术体制，面向未来星载应用，完成星载海洋剖面多要素探测载荷系统设计。其中，激光器谱段设计为486、532 nm多波长一体化最佳配比输出，光电接收探测系统选用1 m×5 m超大口径可折叠光栅主镜，经过仿真分析，探测系统可实现大洋水深100 m深度、温度、盐度以及后向散射系数等多要素同源探测能力，同等体积包络条件下，能量收集能力提升5倍。

In this letter, an enhancement-mode (E-mode) GaN p-channel field-effect transistor (p-FET) with a high current density of ?4.9 mA/mm based on a O₃-Al₂O₃/HfO₂ (5/15 nm) stacked gate dielectric was demonstrated on a p⁺⁺-GaN/p-GaN/AlN/AlGaN/AlN/GaN/Si heterostructure. Attributed to the p⁺⁺-GaN capping layer, a good linear ohmic I?V characteristic featuring a low-contact resistivity (ρ_c) of 1.34 × 10^?4 Ω·cm² was obtained. High gate leakage associated with the HfO₂ high-k gate dielectric was effectively blocked by the 5-nm O₃-Al₂O₃ insertion layer grown by atomic layer deposition, contributing to a high I_ON/I_OFF ratio of 6 × 10⁶ and a remarkably reduced subthreshold swing (SS) in the fabricated p-FETs. The proposed structure is compelling for energy-efficient GaN complementary logic (CL) circuits.

金属有机化学气相沉积(MOCVD)方法制备InGaN/GaN多量子阱结构时, 在GaN势垒层生长的N₂载气中引入适量H₂, 能够有效改善阱/垒界面质量从而提升发光效率。 本工作利用光致发光(PL)光谱技术, 对蓝光激光器结构中的InGaN/GaN多量子阱的发光性能进行了精细的光谱学测量与表征, 研究了通H₂生长对量子阱界面的调控效应及其发光效率提升的物理机制。 室温PL光谱结果显示, GaN势垒层生长载气中引入2.5%的H₂使InGaN/GaN多量子阱的发光效率提升了75%、 发光峰的峰位蓝移了17 meV、 半峰宽(FWHM)减小了10 meV。 通过功率依赖的PL光谱特征分析, 我们对InGaN/GaN量子阱中的量子限制Stark效应(QCSE)和能带填充(Band Filling)效应进行了清晰的辨析, 发现了发光峰峰位和峰宽的光谱特征主要受QCSE效应影响, H₂的引入能够大幅度降低QCSE效应, 并且确定了QCSE效应被完全屏蔽情况下的发光峰能量为2.75 eV。 温度依赖的PL光谱数据揭示了通H₂生长量子阱结构中显著减弱的载流子局域化行为, 显示界面质量提高有效降低了限制势垒的能量波动, 从而导致更窄的发光峰半峰宽。 PL光谱强度随温度的变化规律表明, 通H₂生长并不改变量子阱界面处的非辐射复合中心的物理本质, 却能够显著减少非辐射复合中心的密度, 有助于提升量子阱的发光效率。 通过时间分辨PL光谱分析, 发现通H₂生长会导致量子阱结构中更短的载流子辐射复合寿命, 但不影响非辐射复合寿命。 载流子复合寿命的变化特征进一步确认了通H₂生长对量子阱结构中QCSE效应和非辐射复合中心的影响规律。 综合所有PL光谱分析结果, 我们发现通H₂生长能够提高InGaN/GaN多量子阱的界面质量、 显著减弱应力效应(更弱的QCSE效应)、 降低限制势垒的能量波动以及减少界面处非辐射复合中心的密度, 从而显著提升量子阱的发光效率。 该研究工作充分显示了PL光谱技术对半导体量子结构发光性能的精细表征能力, 光谱分析结果能够为InGaN/GaN多量子阱生长提供有价值的参考。

Stereoscopic microscopy is a promising technology to obtain three-dimensional microscopic images. Such microscopes are based on the parallax effect, and as such require two lenses to focus at two different points. Geometrical constraints, however, restrict their numerical apertures to about 0.2, thus limiting the system’s resolution. Higher numerical apertures (∼0.35) can be achieved with designs using only one bulk lens, but such systems are ∼10 times more costly than the conventional ones. Thus, there is a pressing need for alternative solutions to improve the resolution of stereoscopic systems. Here, we show that high-resolution and low-cost stereoscopic systems can be obtained using birefringent single-layer metalenses. We design and fabricate a birefringent metalens operating at 532 nm with a numerical aperture as high as 0.4. The metalens is then used to demonstrate high-resolution stereoscopic imaging of biological samples. The microscopic images are further displayed and perceived vividly in an autostereoscopic display. Our demonstration paves the way to a new strategy to achieve high-resolution and low-cost stereoscopic microscopes.