共查询到19条相似文献,搜索用时 187 毫秒
1.
2.
本文开展了基于单光子调制频谱测量量子点荧光寿命动力学特性的研究.在脉冲激光激发下,对探测到的量子点单光子荧光信号进行频谱分析以获得荧光调制频谱,研究发现特征频谱信号幅值与荧光寿命之间存在确定的非线性对应关系.这种单光子调制频谱方法能有效消除背景噪声和单光子探测器暗计数的影响,用于分析量子点荧光寿命动力学特性时在准确度以及时间分辨率方面都较目前普遍采用的荧光衰减曲线寿命拟合方法呈现出明显优势:当涨落误差为5%时,寿命测量准确度提高了一个数量级;当涨落误差和偏离误差均为5%时,对动力学测量效率以及时间分辨率提高了四倍以上.因此单光子调制频谱可以作为获取量子点在短时间尺度内激发态动力学信息的一种有效技术手段. 相似文献
3.
4.
利用N型半导体纳米材料氧化铟锡(ITO)作为单CdSe/ZnS量子点的基质来抑制单量子点的荧光闪烁特性. 实验采用激光扫描共聚焦显微成像系统测量了单量子点荧光的亮、暗态持续时间的概率密度分布的指数截止的幂律特性, 并与直接吸附在SiO2玻片上的单CdSe/ZnS量子点的荧光特性进行比较. 研究发现处于ITO中的单量子点比SiO2玻片上的单量子点荧光亮态持续时间提高两个数量级, 掺杂于ITO中的单量子点的荧光寿命约减小为SiO2玻片上的单量子点的荧光寿命的41%, 并且寿命分布宽度变小50%. 相似文献
5.
6.
7.
光量子比特是量子计算和量子通信的理想候选体系之一。高效率、高品质、确定性的单光子源是实现光学量子计算和绝对安全量子通信的重要前提条件。自组装半导体量子点,又称“人造原子”,具有优良的单光子性和光子全同性,是理想的单光子源。此外,量子点可以通过外加电场,囚禁单个原子或空穴,作为光子-自旋比特的界面,构建可扩展光量子网络。微柱腔耦合的量子点,拥有很强的Purcell效应,在保持单光子性和光子全同性的同时,大大地提高了提取效率,且具有很好的相干性,可用于大规模量子计算。近年来,人们在二维单原子层材料中发现了非经典的单光子发射,使二维材料和量子光学领域得到了结合,开辟了新的研究路线:探索单原子层材料在量子技术的潜在应用。和传统固态单光子源系统相比,二维材料更易于与其他光电平台结合,可人为控制缺陷位置,有利于推动高品质、低成本单光子源的发展,得到了科学家的广泛关注。本报告首先从量子计算和量子通信两方面提出发展单光子源的意义,接着介绍单光子源的性质和产生原理,然后介绍单光子源在自组装半导体量子点和二维单原子层材料中的实现和发展,最后从光子-自旋量子隐形传态和玻色采样实验中讨论单光子源在量子计算和量子网络方面的应用前景。 相似文献
8.
对目前的腔QED系统实现强耦合的条件进行了讨论.主要内容包括:获得强耦合的一般条件,我们目前的可能达到的最好结果分析:不同腔组合可能达到的参数,与量子点、光子晶体、纳米腔以及微球腔QED的比较;单原子(单光子)测量的基本过程:单原子辐射的基本特点,非经典性的测量,包括差拍测量,光子统计特性的分析.不同单光子量子态(或多光子量子态)在采用HBT实验测量中的修正等问题.对热光和相干光的初步实验对比证实了理论模型.原子操控的进展:铯原子光学偶极俘获,最近的实验结果,利用CCD荧光探测对偶极阱的测量结果. 相似文献
9.
10.
针对量子点场效应单光子探测器(QDFET)光吸收效率低下的问题, 提出了一种新型量子点场效应增强型单光子探测器(QDFEE-SPD). QDFEE-SPD增加了共振腔的设计, 并采用了GaAs/AlAs多层膜作为下反射镜; 对QDFEE-SPD的光吸收增强效应和光响应度进行了理论分析和模拟, 结果表明, 与没有共振腔时相比, QDFEE-SPD的吸收效率和光相应度都有了大幅度的提升, 同时为了光吸收的最优化, 吸收层厚度一般应在0.1–0.5 μm; 对QDFEE-SPD的材料样品进行了生长和测试实验, 反射谱测试和PL谱测试结果表明, QDFEE-SPD对入射光的吸收具有了明显的增强效应. 文章成果为高效率量子点场效应单光子探测技术的研究提供了新的思路.
关键词:
QDFEE-SPD
共振腔
吸收效率
光吸收增强效应 相似文献
11.
A method to obtain ground state electroluminescence from 1.3μm emitting InAs/GaAs quantum dots grown by molecular beam epitaxy 下载免费PDF全文
1.3μm emitting InAs/GaAs quantum dots(QDs) have been grown by molecular beam epitaxy and QD light emitting diodes(LEDs) have been fabricated.In the electroluminescence spectra of QD LEDs,two clear peaks corresponding to the ground state emission and the excited state emission are observed.It was found that the ground state emission could be achieved by increasing the number of QDs contained in the active region because of the state filling effect.This work demonstrates a way to control and tune the emitting wavelength of QD LEDs and lasers. 相似文献
12.
Epitaxially grown self-assembled InAs quantum dots (QDs) have found applications in optoelectronics. Efforts are being made
to obtain efficient quantum-dot lasers operating at longer telecommunication wavelengths, specifically 1.3 μm and 1.55 μm.
This requires narrow emission linewidth from the quantum dots at these wavelengths. In InAs/GaAs single layer quantum dot
(SQD) structure, higher InAs monolayer coverage for the QDs gives rise to larger dots emitting at longer wavelengths but results
in inhomogeneous dot-size distribution. The bilayer quantum dot (BQD) can be used as an alternative to SQDs, which can emit
at longer wavelengths (1.229 μm at 8 K) with significantly narrow linewidth (∼16.7 meV). Here, we compare the properties of
single layer and bilayer quantum dots grown with higher InAs monolayer coverage. In the BQD structure, only the top QD layer
is covered with increased (3.2 ML) InAs monolayer coverage. The emission line width of our BQD sample is found to be insensitive
towards post growth treatments. 相似文献
13.
Kouichi Akahane Naokatsu Yamamoto Naoki Ohtani 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):295
We fabricated InAs quantum dots (QDs) with a GaAsSb strain-reducing layer (SRL) on a GaAs(0 0 1) substrate. The wavelength of emission from InAs QD is shown to be controllable by changing the composition and thickness of the SRL. An increase in photoluminescence intensity with increasing compositions of Sb and thickness of the GaAsSb SRL is also seen. The efficiency of radiative recombination was improved under both conditions because the InAs/GaAsSb/GaAs hetero-interface band structure more effectively suppressed carrier escape from the InAs QDs. 相似文献
14.
PHOTOLUMINESCENCE STUDY OF InAs/GaAs SELF-ORGANIZED QUANTUM DOTS WITH BIMODAL SIZE DISTRIBUTION 下载免费PDF全文
We have investigated the temperature dependence of the photoluminescence (PL) spectrum of self-organized InAs/GaAs quantum dots. A distinctive double-peak feature of the PL spectra from quantum dots has been observed, and a bimodal distribution of dot sizes has also been confirmed by scanning tunneling microscopy image for uncapped sample. The power-dependent PL study demonstrates that the distinctive PL emission peaks are associated with the ground-state emission of islands in different size branches. The temperature-dependent PL study shows that the PL quenching temperature for different dot families is different. Due to lacking of the couple between quantum dots, an unusual temperature dependence of the linewidth and peak energy of the dot ensemble photoluminescence has not been observed. In addition, we have tuned the emission wavelength of InAs QDs to 1.3 μm at room temperature. 相似文献
15.
Lasers operating at 1.3 μm have attracted considerable attention owing to their potential to provide efficient light sources for next-generation high-speed communication systems. InAs/GaAs quantum dots (QDs) were pointed out as a reliable low-cost way to attain this goal. However, due to the lattice mismatch, the accumulation of strain by stacking the QDs can cause dislocations that significantly degrade the performance of the lasers. In order to reduce this strain, a promising method is the use of InAs QDs embedded in InGaAs layers. The capping of the QD layer with InGaAs is able to tune the emission toward longer and controllable wave-lengths between 1.1 and 1.5 μm. In this work, using the effective-mass envelope-function theory, we investigated theoretically the optical properties of coupled InAs/GaAs strained QDs based structures emitting around 1.33 μm. The calculation was performed by the resolution of the 3D Schrödinger equation. The energy levels of confined carriers and the optical transition energy have been investigated. The oscillator strengths of this transition have been studied with and without taking into account the strain effect in the calculations. The information derived from the present study shows that the InGaAs capping layer may have profound consequences as regards the performance of an InAs/GaAs QD based laser. Based on the present results, we hope that the present work make a contribution to experimental studies of InAs/GaAs QD based structures, namely the optoelectronic applications concerning infrared and mid-infrared spectral regions as well as the solar cells. 相似文献
16.
J. Chen W. J. Fan Y. Ding Q. Xu X. W. Zhang D. W. Xu S. F. Yoon D. H. Zhang 《Opto-Electronics Review》2011,19(4):449-453
We apply 8-band k.p model to study InAs/GaAs quantum dots (QDs). The strain was calculated using the valence force field (VFF)
model which includes the four nearest-neighbour interactions. For the optical properties, we take into account both homogeneous
and non-homogeneous broadening for the optical spectrum. Our simulation result is in good agreement with the experimental
micro-photoluminescence (μ-PL) result which is from InAs/GaAs QD vertical cavity surface emitting lasers (VCSELs) structure
wafer at room temperature. Accordingly, our simulation model is used to predict the QD emission from this QD-VCSELs structure
wafer at different temperature ranging from 200–400 K. The simulation results show a decrease of 41 meV of QD ground state
(GS) transition energy from 250–350 K. The changes of QDGS transition energy with different temperature indicate the possible
detuning range for 1.3-μm wave band QD-VCSELs applications without temperature control. Furthermore, QD differential gain
at 300 K is computed based on this model, which will be useful for predicting the intrinsic modulation characteristics of
QD-VCSELs. 相似文献
17.
利用固源分子束外延(MBE)的方法经SK模式自组装生长由多层InAs/GaAs量子点组成的柱形岛.具体分析了GaAs间隔层厚度,生长停顿时间以及InAs淀积量对发光峰波长的影响.原子力显微镜(AFM)结果显示柱形岛表面的形状和尺寸都比较均匀;室温下不同高度的柱形岛样品的发光波长分别达到1.32和1.4μm,而单层量子点的发光波长仅为1.1μm,充分说明了量子点高度对发光波长的决定性影响,这为调节量子点发光波长提供了一种直观且行之有效的方法.
关键词:
柱形岛
生长停顿
间隔层厚度
PL谱 相似文献
18.
A broadband external cavity tunable InAs/GaAs quantum dot laser by utilizing only the ground state emission 下载免费PDF全文
A broadband external cavity tunable laser is realized by using a broad-emitting spectral InAs/GaAs quantum dot (QD) gain device. A tuning range of 69 nm with a central wavelength of 1056 nm, is achieved at a bias of 1.25 kA/cm2 only by utilizing the light emission from the ground state of QDs. This large tunable range only covers the QD ground-state emission and is related to the inhomogeneous size distribution of QDs. No excited state contributes to the tuning bandwidth. The application of the QD gain device to the external cavity tunable laser shows its immense potential in broadening the tuning bandwidth. By the external cavity feedback, the threshold current density can be reduced remarkably compared with the free-running QD gain device. 相似文献
19.
We have demonstrated the selective area growth of stacked self-assembled InAs quantum dot (QD) arrays in the desired regions on a substrate and confirmed the photoluminescence (PL) emission exhibited by them at room temperature. These InAs QDs are fabricated by the use of a specially designed atomic force microscope cantilever referred to as the Nano-Jet Probe (NJP). By using the NJP, two-dimensional arrays with ordered In nano-dots are fabricated in the desired square regions on a GaAs substrate and directly converted into InAs QD arrays through the subsequent annealing by the irradiation of As flux. By using the converted QD arrays as strain templates, self-organized InAs QDs are stacked. These stacked QDs exhibit the PL emission peak at a wavelength of 1.02 μm. 相似文献