纳米金属粒子光吸收理论研究进展

纳米金属粒子具有不同于块体材料的独特的光学性质,因而它在光化学、纳米含能材料及药物等许多领域有着广泛且重要的应用.本文系统的总结了分散在介质中的纳米金属粒子的光吸收理论公式及其适用范围,介绍了各种因素如尺寸、形状以及尺寸和形状分布对光吸收性质影响的计算方法.指出了当前纳米金属粒子光吸收性质方面的研究热点.     

High-speed phase- and group-delay scanning with a grating-based phase control delay line

A rapid-scanning optical delay line that employs phase control has several advantages, including high speed, high duty cycle, phase- and group-delay independence, and group-velocity dispersion compensation, over existing optical delay methods for interferometric optical ranging applications. We discuss the grating-based phase-control delay line and its applications to interferometric optical ranging and measurement techniques such as optical coherence domain reflectometry and optical coherence tomography. The system performs optical ranging over an axial range of 3 mm with a scanning rate of 6m/s and a repetition rate of 2 kHz. The device is especially well suited for applications such as optical coherence tomography that require high-speed, repetitive, linear delay line scanning with a high duty cycle.     

Fluorescent Metallic Nanoclusters: Electron Dynamics,Structure, and Applications

Atomically precise Au nanoclusters (NCs) have emerged as fascinating fluorescent nanomaterials and attracted considerable research interest in both fundamental research and practical applications. Due to enhanced quantum confinement, they possess extraordinary optical, electronic, and magnetic properties and therefore are very promising for a wide range of applications, including biosensing, bioimaging, catalysis, photonics, and molecular electronics. Remarkable progress has been reported for the fundamental understanding, synthesis techniques, and applications. In this review, the updated advances are summarized in Au NCs, including synthesis techniques, optical properties, and applications. In particular, we focus on the optical properties and electron dynamic processes. In addition, the progress in other noble metallic NCs is included in this Review, such as Ag, Cu, Pt, and alloy, which have attracted much research interest recently. Finally, an outlook is presented for such fascinating nanomaterials in both aspects of future fundamental research and potential applications.     

光纤激光模场及表征技术进展

在光纤通信、光纤激光器和光纤传感等领域的实际应用中,需要重点关注光纤中的模式问题。模分复用是提高光通信信息容量的有效方法,模间干涉是大多数光纤传感的基本方法,高功率光纤激光的光束质量控制的关键技术之一就是模式控制,因此,对光纤模式理论、模式产生及转换、模式表征技术开展研究具有重要的研究意义和实际应用价值。论文讨论了光纤的模式及光束质量,分析了多种模式发生及转换的方法,将模式表征方法归结为非相干、相干和低相干测量法。光纤模式表征是目前的研究热点,在多种表征方法中,空间和频谱成像法（S2）和双重傅里叶变换法（F2）具有显著的优越性,可不需要提前知道光纤的几何参数,就可获得模场分布、模式功率占比、群时延等特性。研究表明F2法更适合于表征高功率光纤激光的模场特性。     

Resource Letter: LBOT-1: Laser-based optical tweezers

This Resource Letter provides a guide to the literature on optical tweezers, also known as laser-based, gradient-force optical traps. Journal articles and books are cited for the following main topics: general papers on optical tweezers, trapping instrument design, optical detection methods, optical trapping theory, mechanical measurements, single molecule studies, and sections on biological motors, cellular measurements and additional applications of optical tweezers.     

非线性有机材料DAST的研究及应用

随着光通信、光信息处理技术等的快速发展,非线性光学材料越来越受到学术界与工业的关注。与无机非线性光学材料相比,有机非线性光学材料具有响应时间短、易于加工和高非线性系数等优点。其中,4-(4-二甲氨基苯乙烯基)甲基吡啶对甲苯磺酸盐(DAST)是人工设计的一种具有非中心对称性和较强极化率的有机非线性材料。大量理论和实验结果表明,DAST具有高二阶光学非线性系数、高电光系数、大双折射率差和低介电常数等特性,能够产生更快、更强的光学非线性响应,还具有优异的太赫兹波发射及吸收性能,是目前综合性能最优、应用最广、最具研究价值的非线性有机材料。近年光谱研究显示,DAST还表现出各向异性的太赫兹光谱特性。文章系统地总结了DAST晶体在太赫兹波发射、二次谐波产生、电光探测和电光调制等众多领域的国内外研究成果,还概括了我们团队近期在DAST基薄膜、太赫兹光谱、光电特性、超材料等新领域的研究进展。此外,还提出将准相位匹配法用于DAST晶体研究、利用电场或自组装膜诱导生长DAST晶体等新思路。对DAST成果的总结和梳理,将促进非线性DAST有机材料在电光调制器、频率转换器、THz探测器等重要领域的应用与理论研究,使其能够更加广泛地应用在光通信、光信息处理、军事技术等重要领域。     

Drive to miniaturization: integrated optical networks on mobile platforms

With rapid growth of the Internet, bandwidth demand for data traffic is continuing to explode. In addition, emerging and future applications are becoming more and more network centric. With the proliferation of data communication platforms and data-intensive applications (e.g. cloud computing), high-bandwidth materials such as video clips dominating the Internet, and social networking tools, a networking technology is very desirable which can scale the Internet’s capability (particularly its bandwidth) by two to three orders of magnitude. As the limits of Moore’s law are approached, optical mesh networks based on wavelength-division multiplexing (WDM) have the ability to satisfy the large- and scalable-bandwidth requirements of our future backbone telecommunication networks. In addition, this trend is also affecting other special-purpose systems in applications such as mobile platforms, automobiles, aircraft, ships, tanks, and micro unmanned air vehicles (UAVs) which are becoming independent systems roaming the sky while sensing data, processing, making decisions, and even communicating and networking with other heterogeneous systems. Recently, WDM optical technologies have seen advances in its transmission speeds, switching technologies, routing protocols, and control systems. Such advances have made WDM optical technology an appealing choice for the design of future Internet architectures. Along these lines, scientists across the entire spectrum of the network architectures from physical layer to applications have been working on developing devices and communication protocols which can take full advantage of the rapid advances in WDM technology. Nevertheless, the focus has always been on large-scale telecommunication networks that span hundreds and even thousands of miles. Given these advances, we investigate the vision and applicability of integrating the traditionally large-scale WDM optical networks into miniaturized mobile platforms such as UAVs. We explain the benefits of WDM optical technology for these applications. We also describe some of the limitations of WDM optical networks as the size of a vehicle gets smaller, such as in micro-UAVs, and study the miniaturization and communication system limitations in such environments.     

光场压缩态的产生及其在亚散粒噪声光学测量和量子信息中的应用

光场压缩态是一种非经典光场,它在超标准量子极限（SQL）的高精度光学测量、超低噪声光通信及量限通信等有着广泛应用前景,是物理学和信息科学交叉前沿研究课题,文章介绍了光场压缩态的产生及它在亚散粒噪声光学测量（sub-shot-noise=limit opical measurement）和量子信息中的重要应用。     

光脉冲在微环耦合谐振光波导中传输线性特性的数值仿真

利用传输矩阵法得到了微环耦合谐振光波导色散关系的一般表达式,并由色散关系出发讨论了光脉冲在微环耦合谐振光波导中传输时的线性特性,包括带宽、群速度、色散和线性相位变化,这些特性对微环耦合谐振光波导在光通信和光传感领域的应用有重要意义. 关键词： 微环光波导 光脉冲线性特性 传输矩阵法 数值仿真     

Interferometric ultrafast SOA-based optical switches: From devices to applications

All-optical switches are fundamental building blocks for future, high-speed optical networks that utilize optical time division multiplexing (OTDM) techniques to achieve single channel data rates exceeding 100 Gb/s. Interferometric optical switches using semiconductor optical amplifier (SOA) non-linearities perform efficient optical switching with < 500 fJ of control energy and are approaching optical sampling bandwidths of nearly 1 THz. In this paper, we review work underway at Princeton University to characterize and demonstrate these optical switches as processing elements in practical networks and systems. Three interferometric optical switch geometries are presented and characterized. We discuss limitations on the minimum temporal width of the switching window and prospects for integrating the devices. Using these optical switches as demultiplexers, we demonstrate two 100-Gb/s testbeds for photonic packet switching. In addition to the optical networking applications, we have explored simultaneous wavelength conversion and pulse width management. We have also designed high bandwidth sampling systems using SOA-based optical switches as analog optical sampling gates capable of analyzing optical waveforms with bandwidths exceeding 100 GHz. We believe these devices represent a versatile approach to all-optical processing as a variety of applications can be performed without significantly changing the device architecture.     

Optical interaction between one-dimensional fiber photonic crystal microcavity and gold nanorod

Localized surface plasmon resonance(LSPR) has demonstrated its promising capability for biochemical sensing and surface-enhanced spectroscopy applications. However, harnessing LSPR for remote sensing and spectroscopy applications remains a challenge due to the difficulty in realizing a configuration compatible with the current optical communication system. Here, we propose and theoretically investigate a hybrid plasmonic-photonic device comprised of a single gold nanorod and an optical fiber-based one-dimensional photonic crystal microcavity, which can be integrated with the optical communication system without insertion loss. The line width of the LSPR, as a crucial indicator that determines the performances for various applications, is narrowed by the cavity-plasmon coupling in our device. Our device provides a promising alternative to exploit the LSPR for high-performance remote sensing and spectroscopy applications.     

Simultaneous Preparation of Two Optical Cat States Based on a Nondegenerate Optical Parametric Amplifier

The cat state, known as the superposition of coherent states, has broad applications in quantum computation and quantum metrology. Increasing the number of optical cat states is crucial to implement complex quantum information tasks based on them. Here, two optical cat states are prepared simultaneously based on a nondegenerate optical parametric amplifier. By subtracting one photon from each of two squeezed vacuum states, two odd cat states with orthogonal superposition direction in phase space are prepared simultaneously, which have similar fidelity of 60% and amplitude of 1.2. Compared with the traditional method to generate two odd optical cat states based on two degenerate optical parametric amplifiers, only one nondegenerate optical parametric amplifier is applied in this experiment, which saves half of the quantum resources of nonlinear cavities. The presented results make a step toward preparing the four-component cat state, which has potential applications in fault-tolerant quantum computation.     

由相干制备原子系统构成的理想光学介质

电磁感应透明(electromagnetically induced transparency,EIT)发生时所伴随的效应(如可控的线性吸收和色散,可控的非线性增强)是理想光学介质所必需的重要特性。通过理解这种相干制备的多能级原子系统的线性和非线性特征,人们能够更好地设计和利用这种新颖的光学介质,并将其应用到光通信和量子信息处理中。文章简单介绍了与EIT有关的原子介质的基本(线性和非线性)光学特性,并简单评价了几个令人感兴趣的应用。     

光纤延迟线型全光缓存器的研究

概括了本课题组在近十年中进行的光纤延迟线型全光缓存器的研究工作,介绍了基本的基于3×3平行排列耦合器的基本缓存单元——双环耦合全光缓存器(DLOB),并以此为基础,构建出缓存时间为1～9999 T(时间单位)的大动态范围、多波长等全光缓存器,速率都在2.5 Gb/s以上,并研制出基于偏振的全光缓存器.对这些缓存器的原理...     

Two-dimensional materials-decorated microfiber devices for pulse generation and shaping in fiber lasers

Two-dimensional(2D) materials have been regarded as a promising nonlinear optical medium for fabricating versatile optical and optoelectronic devices. Among the various photonic applications, the employment of 2D materials as nonlinear optical devices such as saturable absorbers for ultrashort pulse generation and shaping in ultrafast lasers is one of the most striking aspects in recent years. In this paper, we review the recent progress of 2D materials based pulse generation and soliton shaping in ultrafast fiber lasers, and particularly in the context of 2D materials-decorated microfiber photonic devices. The fabrication of 2D materials-decorated microfiber photonic devices, high performance mode-locked pulse generation, and the nonlinear soliton dynamics based on pulse shaping method are discussed. Finally, the challenges and the perspective of the 2D materials-based photonic devices as well as their applications are also discussed.     

Enhanced light trapping for the silver nanoparticles embedded in the silica layer atop the silicon substrate

The optical properties of the structures with silver nanoparticles embedded in the silica layer atop the silicon substrate are simulated by the finite-difference time-domain method. The effects of nanoparticle size, period, silica layer thickness, and the angle of incidence of the illuminated light on optical transmissions are studied. It is found that there is the red-shift for the maximum of the total light transmitting into the silicon substrate as the silica layer thickness increases. The electric field intensity distributions and the average power densities for the structure with largest optical transmission is studied, and the strong electric field intensities are found in the silica regions surrounding to the silver nanoparticles, which can help the light energy going into the silicon substrate. By controlling the structure parameters, the optical transmissions of the structures with the silica layer can have higher optical transmissions than the cases without the silica layer. The silica layer plays the role as the graded refractive index layer between the air and the silicon substrate, and the light power from the incident wave can transmit into the silicon substrate with less optical reflections for choosing a suitable silica layer thickness. A guideline to design the structures with high optical transmissions for the solar spectra is given. This study cannot only be useful for the solar cells applications, but also other antireflection applications.     

Induced transparency in nanoscale plasmonic resonator systems

An optical effect analogous to electromagnetically induced transparency (EIT) is observed in nanoscale plasmonic resonator systems. The system consists of a slot cavity as well as plasmonic bus and resonant waveguides, where the phase-matching condition of the resonant waveguide is tunable for the generation of an obvious EIT-like coupled resonator-induced transparency effect. A dynamic theory is utilized to exactly analyze the influence of physical parameters on transmission characteristics. The transparency effect induced by coupled resonance may have potential applications for nanoscale optical switching, nanolaser, and slow-light devices in highly integrated optical circuits.     

Experimental characterization of simultaneous spatial and spectral filtering by an optical resonant filter

Simultaneous spatial and spectral filtering by an optical resonant filter has been characterized experimentally to furnish additional insight into the operation and applications of optical resonant filters. Our experimental study can be useful for applications that depend on spatial filtering, spectral filtering, spatial-spectral filtering, and polarization selectivity. One significant application is the integration of an optical resonant filter with semiconductor lasers to control the spatial-spectral radiation for optimum performance.     

荧光光谱及其成像技术在光活检中的应用

分析了人体组织自体荧光的主要物质来源和荧光特性,同时总结了国内外常见的第二代新型光敏剂及其临床应用情况。在此基础上,全面比较了各种应用于早期肿瘤光活检的荧光光谱及其成像技术,并重点讨论了这些技术的基本原理和临床应用现状,以及它们今后的发展方向。     

Generation of Circular Optical Vortex Array

We report on a novel optical vortex array named circular optical vortex array, which is generated by the superposition of two concentric perfect optical vortices. The circular optical vortex array has a constant topological charge of +1 or ?1, the number and sign of which are determined by the topological charges of the two perfect optical vortices. Moreover, the radius of the circular optical vortex array is easily adjusted by using the cone angle of an axicon. Furthermore, the circular optical vortex array and multiple circular optical vortex array can be rotated by changing the initial phase difference of the perfect optical vortices on demand. This work demonstrates a complex structured optical field, which is of significance for applications such as optical tweezers, micro‐particle manipulation, and optical imaging.