GaN has been widely used in the fabrication of ultraviolet photodetectors because of its outstanding properties. In this paper, we report a graphene–GaN nanorod heterostructure photodetector with fast photoresponse in the UV range. GaN nanorods were fabricated by a combination mode of dry etching and wet etching. Furthermore, a graphene–GaN nanorod heterostructure ultraviolet detector was fabricated and its photoelectric properties were measured. The device exhibits a fast photoresponse in the UV range. The rising time and falling time of the transient response were 13 and 8 ms, respectively. A high photovoltaic responsivity up to 13.9 A/W and external quantum efficiency up to 479% were realized at the UV range. The specific detectivity D* = 1.44 × 1010 Jones was obtained at –1 V bias in ambient conditions. The spectral response was measured and the highest response was observed at the 360 nm band.
Journal of Semiconductors
2022, 43(6): 062804
为了降低微盘腔半导体激光器工作时有源区的温度, 提升封装的可靠性, 基于Ansys Workbench有限元分析分别对AlN, WCu10, SiC, 石墨烯, 以及CVD金刚石过渡热沉封装的蜗线型微盘腔半导体激光器进行了热特性分析, 得到了器件工作时的温度分布以及热应力、热应变分布。结果显示, SiC封装器件的有源区温度较AlN和WCu10封装器件分别降低了2.18, 3.078℃, 并在五种过渡热沉封装器件中表现出最低的热应力, 器件热应变最小。SiC过渡热沉封装可以有效降低微盘腔半导体激光器工作时的有源区温度, 同时减少封装应力与器件应变, 从而提高器件的散热能力和可靠性。计算结果对半导体激光器单管散热及阵列集成散热均有指导意义。微盘腔半导体激光器 过渡热沉 ANSYS热分析 热应力 micro-disk cavity semiconductor laser transition heat sink ANSYS thermal analysis thermal stress
Optical chirp chain Brillouin optical time-domain analysis (OCC-BOTDA) has the capabilities of fast measurement, high Brillouin threshold, and freedom from the nonlocal effect; at the same time, however, it also has problems introduced by transient stimulated Brillouin scattering. The influence of the transient interaction is reflected as the broadened asymmetric Brillouin spectrum, the ghost peak, and the frequency shift of the main peak. This introduces difficulty in computing the fiber Brillouin frequency shift with good measurement accuracy. Besides, the OCC modulation causes additional noise due to the uneven amplitude response for different frequency components. In this work, we propose a high-performance OCC-BOTDA using the principal component analysis (PCA) based pattern recognition algorithm and differential pulse-width pair (DPP) technique. After building the Brillouin spectrum database (i.e., all patterns), the fiber intrinsic Brillouin frequency shift can be recognized by the PCA algorithm from a nonstandard Brillouin spectrum profile, resulting in good measurement accuracy. Meanwhile, the DPP technique, subtracting between two Brillouin signals generated by two wide-width pump pulses, is utilized to reduce the OCC modulation noise and avoid the pulse self-phase modulation effect in long-range BOTDA sensing. In the experiment, a temperature measurement with 1.3?MHz measurement precision, 4?m spatial resolution, and 5?s measurement time is achieved over a 100?km single-mode fiber.
2019, 7(6): 06000652
布里渊光纤传感通过光纤中受激布里渊散射效应实现温度和应变测量，具有空间分辨率高、传感距离长和测量精度高等特点，因此分布式布里渊光纤传感成为近年的研究热点。本文通过对长距离分布式布里渊光纤传感研究进展的调研和分析，概括了长距离布里渊传感面临的主要限制因素和解决的关键技术，重点介绍了基于时分复用、频分复用、脉冲编码、宽带频率调制和图像处理算法的长距离布里渊光纤传感技术。随着长距离布里渊光纤传感器的实际工程化，对于快速测量的需求愈发显著，这将是未来长距离布里渊光纤传感的主要研究方向。受激布里渊散射 布里渊光时域分析 光纤传感 非线性光学 stimulated Brillouin scattering Brillouin optical time domain analysis optical fiber sensing nonlinear optics