Design of 2-to-4 All-Optical Decoder with the Help of Terahertz Optical Asymmetric Demultiplexer

An all-optical 2-to-4 decoder unit with the assist of terahertz optical asymmetric demultiplexer (TOAD) is presented. The all-optical 2-to-4 decoder with a set of all-optical switches is designed which can be used to achieve a high-speed central processor unit using optical hardware. The unique output lines can be used for all-optical header processing. We attempt to develop an integrated all-optical circuit which can perform decoding of signal. This scheme is very simple and flexible for performing different logic operation and to design advanced complex logic. Simulated results are confirming the described methods.

High-Speed Time-Domain En Face Optical Coherence Tomography System Using KTN Optical Beam Deflector

We developed high-speed time-domain (TD) en face optical coherence tomography (OCT) system using KTN optical beam deflector. The KTN optical beam deflector operates at a high repetition rate of 200 kHz with a fairly large beam deflection angle. We proposed a high-speed en face OCT system that used a KTN optical deflector as the sample beam scanning. In the experiment, we obtained en face OCT images of human fingerprint with a frame rate of 800 fps, which is the fastest speed obtained by a TD-OCT imaging. Furthermore, a 3D-OCT image was also obtained at 0.2 s (=5 volumes/s) by our imaging system.

Software Defined Optical Networks and Its Innovation Environment

Software defined optical networks （SDONs） integrate software defined technology with optical communication networks and represent the promising development trend of future optical networks. The key technologies for SDONs include software-defined optical transmission, switching, and networking. The main features include control and transport separation, hard-ware universalization, protocol standardization, controllable optical network, and flexible optical network applications. This paper introduces software defined optical networks and its innovation environment, in terms of network architecture, protocol extension solution, experiment platform and typical applications. Batch testing has been conducted to evaluate the performance of this SDON testbed. The results show that the SDON testbed has good scalability in different sizes. Meanwhile, we notice that controller output bandwidth has great influence on lightpath setup delay.

Anti-Spoof Reliable Biometry of Fingerprints Using <i>En-Face</i>Optical Coherence Tomography

Optical coherence tomography (OCT) is a relatively new imaging technology which can produce high resolution images of three-dimensional structures. OCT has been mainly used for medical applications such as for ophthalmology and dermatology. In this study we demonstrate its capability in providing much more reliable biometry identification of fingerprints than conventional methods. We prove that OCT can serve secure control of genuine fingerprints as it can detect if extra layers are placed above the finger. This can prevent with a high probability, intruders to a secure area trying to foul standard systems based on imaging the finger surface. En-Face OCT method is employed and recommended for its capability of providing not only the axial succession of layers in depth, but the en-face image that allows the traditional pattern identification. Another reason for using such OCT technology is that it is compatible with dynamic focus and therefore can provide enhanced transversal resolution and sensitivity. Two En-Face OCT systems are used to evaluate the need for high resolution and conclusions are drawn in terms of the most potential commercial route to ex- ploitation.

Generalized Block Markov Superposition Transmission over Free-Space Optical Links

In free-space optical(FSO) communications, the performance of the communication systems is severely degraded by atmospheric turbulence. Channel coding and diversity techniques are commonly used to combat channel fading induced by atmospheric turbulence. In this paper, we present the generalized block Markov superposition transmission(GBMST) of repetition codes to improve time diversity. In the GBMST scheme, information sub-blocks are transmitted in the block Markov superposition manner, with possibly different transmission memories. Based on analyzing an equivalent system, a lower bound on the bit-error-rate(BER) of the proposed scheme is presented. Simulation results demonstrate that, under a wide range of turbulence conditions, the proposed scheme improves diversity gain with only a slight reduction of transmission rate. In particular, with encoding memory sequence(0, 0, 8) and transmission rate 1/3, a diversity order of eleven is achieved under moderate turbulence conditions. Numerical results also show that, the GBMST systems with appropriate settings can approach the derived lower bound, implying that full diversity is achievable.

PERFORMANCE ANALYSIS AND SIMULATION OF OCDMA SYSTEM BASED ON FBGs ENCODER/DECODER

The encoding/decoding scheme based on Fiber Bragg Grating (FBG) for Optical Code Division Multiple Access (OCDMA) system is analyzed and the whole process from transmitting end to receiving end is researched in detail. The mathematical mode including signal transmission, summing, receiving and recovering are established respectively. One of the main sources of Bit Error Rate (BER) of OCDMA system based on FBGs is the unevenness of signal power spectrum, which leads to the chip powers unequal with each other. The Signal to Interfere Ratio (SIR) and BER performance of the system are studied and simulated at the case with uneven distribution of chips' powers.

Optical information transfer through random unknown diffusers using electronic encoding and diffractive decoding

Free-space optical information transfer through diffusive media is critical in many applications, such as biomedical devices and optical communication, but remains challenging due to random, unknown perturbations in the optical path. We demonstrate an optical diffractive decoder with electronic encoding to accurately transfer the optical information of interest, corresponding to, e.g., any arbitrary input object or message, through unknown random phase diffusers along the optical path. This hybrid electronic-optical model, trained using supervised learning, comprises a convolutional neural network-based electronic encoder and successive passive diffractive layers that are jointly optimized. After their joint training using deep learning,our hybrid model can transfer optical information through unknown phase diffusers, demonstrating generalization to new random diffusers never seen before. The resulting electronic-encoder and optical-decoder model was experimentally validated using a 3D-printed diffractive network that axially spans <70λ, whereλ = 0.75 mm is the illumination wavelength in the terahertz spectrum, carrying the desired optical information through random unknown diffusers. The presented framework can be physically scaled to operate at different parts of the electromagnetic spectrum, without retraining its components, and would offer low-power and compact solutions for optical information transfer in free space through unknown random diffusive media.

融合形状结构恢复和细节补偿的双分支点云修复网络

针对传统点云修复中难以有效地保持原始形状细节结构信息的问题,提出一种融合形状全局结构恢复和局部细节补偿的双分支点云形状修复网络.网络中的形状全局结构恢复分支为编解码-解码器结构,编码器对缺失点云数据进行特征变换以克服点云形状的旋转不变性,利用最大池化操作解决点云的无序性问题,并通过多层感知器生成原始点云的特征码字,解码器对编码得到的特征码字使用4个二维网格进行2次折叠操作,拟合点云形状得到粗修复结果;为了补偿点云粗修复结果的形状细节信息,网络中的局部细节补偿分支对编码器提取得到的不同维度特征,通过层次特征学习和多层次特征融合学习点云形状的几何结构特征,有效地恢复缺失点云数据并保留原始形状细节信息;最终将经全局结构恢复分支和局部细节补偿分支分别得到的点云数据拼接融合,再进行迭代最远点重采样,得到点云形状精修复结果.实验结果表明,在ShapeNet数据集上,所提网络比已有网络修复结果的平均CD误差和平均EMD误差分别低16%~29%和19%~65%;在ModelNet数据集上,比已有网络修复结果的平均CD误差和平均EMD误差分别低6%~41%和31%~59%;该网络可以修复原始形状的整体结构信息并能有效地恢复其形状细节,生成采样点分布均匀的完整点云模型,且对模型噪声和不同程度的模型缺失均具有鲁棒性.

OCC系统目标LED阵列解码算法研究

针对强日光环境下OCC(Optical Camera Communication)系统接收端解码困难的问题,提出了基于分段式线性灰度变换的Gradient-Harris解码算法。首先搭建一套OCC实验系统,接收端相机采集原始图像,利用标准相关系数匹配方法提取目标LED阵列区域。其次通过分段式线性灰度变换对目标LED阵列区域进行图像增强,利用Gradient-Harris解码算法进行目标LED阵列的形状提取和状态识别。实验结果表明,应用基于分段式线性灰度变换的Gradient-Harris解码算法,强日光环境下OCC实验系统的平均解码速率为128.08 bit/s,平均误码率为4.38×10^(-4),最大通信距离为55 m。

应用于光模块的低成本曼彻斯特解码方案

为了降低传统光模块行业中曼彻斯特解码方案的成本并提高其兼容性和可靠性,提出了一种应用于光模块的低成本曼彻斯特解码方案。首先,利用采样电阻与运放组合电路对信号进行预处理,解决不同光强条件下采样后信号幅值过小或饱和而无法解码的问题。其次,利用控制器内部的可编程计数阵列(PCA)对信号进行边沿捕捉和持续时间计算,解决信号同步问题。在同步判断过程中,引入了持续时间容差设计,并对数据帧头的丢失进行了优化判断,从而显著提升解码方案的抗干扰能力。最后,利用控制器内部的可编程逻辑单元(CLU)和定时器提取信号时钟,并将信号发送到内部串行外设接口(SPI)模块完成解码,以提高解码效率并解决控制器的资源消耗和解码兼容性问题。测试结果表明,该方案能够进行准确且稳定的数据解码,满足实际的应用需求。

[Cu(H_2O)_2(en)][SO_4]晶体的局域结构和吸收光谱研究

根据赵敏光等提出的半自洽3 d轨道模型和点电荷模型,建立了过渡金属离子晶体的局域结构与吸收光谱之间的定量关系,对[Cu(H2O)2(en)][SO4]晶体的局域结构和吸收光谱进行了统一解释,还预测了其EPR谱的值.其理论计算结果与实验观测值符合.

Improve the throughput of M-to-1 free-space optical systems by employing uniquely decodable codes

This paper utilizes uniquely decodable codes[UDCs]in an M-to-1 free-space optical[FSO]system.Benefiting from UDCs’nonorthogonal nature,the sum throughput is improved.We first prove that the uniquely decodable property still holds,even in optical fading channels.It is further discovered that the receiver can extract each source’s data from superimposed symbols with only one processing unit.According to theoretical analysis and simulation results,the throughput gain is up to the normalized UDC’s sum rate in high signal-to-noise ratio cases.An equivalent desktop experiment is also implemented to show the feasibility of the UDC-FSO structure.

遥测自动气象站及人工EN风数据的远距离传输

介绍一种遥测自动气象站及人工EN风超远距离数据传输的方法,利用设备提供的标准RS232C端口输出数据,并输入到数字光端机,实现光纤传输通讯,最终将地面气象观测数据送入测报计算机。这种通讯方法已在台站得到实际应用。

Symbol error rate performance analysis of soft-decision decoded MPPM free space optical system over exponentiated Weibull fading channels

The symbol error rate （SER） performance of a multipulse pulse-position modulation （MPPM） free space optical （FSO） system under the combined effect of turbulence-induced fading modeled by exponentiated Weibull （EW） distribution and pointing errors with a soft-decision detector is investigated systematically. Particularly, the theoretical conditional SER （CSER） of soft-decision decoded MPPM is derived. The corresponding closed-form CSER is obtained via curve fitting with the Levenberg-Marquardt method. The analytical SER expression over the aggregated fading channels is then achieved in terms of Laguerre integration. Monte Carlo simulation results are also offered to corroborate the validity of the proposed SER model.

Dynamic Analysis of Mental Sweating by the Time-Sequential Piled-Up En-Face OCT Images

In this paper, the dynamic analysis of mental sweating for sound stimulus of a few tens of eccrine sweat glands is performed by the time-sequential piled-up en-face optical coherence tomography (OCT) images with the frame spacing of 3.3 sec. In the experiment, the amount of excess sweat can be evaluated simultaneously for a few tens of sweat glands by piling up of all the en-face OCT images. Strong non-uniformity is observed in mental sweating where the amount of sweat in response to sound stimulus is different for each sweat gland. Furthermore, the amount of sweat is significantly increased in proportion to the strength of the stimulus.

基于光流与注意力机制的句级唇语识别

唇语识别技术是一种利用视觉线索理解人类语言的手段,在人机交互、安防验证、公共安全等领域都有着广泛的应用空间。现阶段的相关研究大多难以有效地完成语句级别的唇语识别任务。设计了一种基于光流与注意力机制的句级唇语识别系统,能够将连续的唇读视频逐句解码为文字。系统由前端的唇读端点检测模块和端对端的神经网络构成,网络的图像特征提取模块基于3D-ResNet18与空间-通道双重注意力机制,时间序列分类模块基于Transformer和集束搜索解码器。唇读端点检测模块基于光流的阈值变化进行判别,对连续输入神经网络的唇读视频按句进行切分。神经网络的训练采用基于标签平滑的KL散度作为损失,并采取样本长度递增、学习率预热、逐级迁移学习等改进策略。模型的评估在英文数据集GRID和中文数据集CMLR上进行,在错误率上相较于基线结果分别降低了3.11%和1.21%。

UV引发硫醇-烯反应制备OLED屏封装用八乙烯基倍半硅氧烷/聚氨酯丙烯酸酯液态光学胶

有机发光器件(OLED)是新一代显示屏,其中用于显示屏组件间粘接的液态光学透明胶(LOCA)是OLED的关键材料之一,高折射率、高导热性及高稳定性的LOCA对OLED性能尤为重要。文中采用八乙烯基倍半硅氧烷(OvPOSS)作为增强填料、三羟甲基丙烷三(3-巯基丙酸酯)(TTMP)作为交联剂,通过简单的UV引发硫醇-烯反应将OvPOSS接枝到具有良好黏附性和光学性能的聚氨酯丙烯酸酯(PUA)树脂中,制备出高透明性高折射率的LOCA。研究表明,制备的LOCA在365 nm UV照射20 s内即可固化,相比商用UV胶几分钟的固化时间,固化速度更快、能耗更低;当OvPOSS的质量分数为7%时,相比纯的PUA,折射率提高到1.525以上,热分解温度(T_(d5%))比纯PUA提高了30℃,玻璃化转变温度提高了5.3℃,导热系数从0.0609 W/(m·K)提高到0.1710 W/(m·K),粘接强度从3.16 MPa提高到3.48 MPa,室温日照1440 h后仍可达到99%以上的可见光透过率,水中浸渍3600 h后吸水率仅为0.52%,低于目前文献中的0.70%(24 h),在光电器件封装中具有较大应用前景。

多路高清图像组合编解码光纤传输技术

针对多传感器视觉设备中高清相机的图像数据流量大、传输带宽要求高的特点,设计了一种基于FPGA的多路高清图像组合编解码器。其采用有限状态机工作方式,对像素数据进行重组编解码,并对多通道图像数据进行通道时分复用编解码,有效利用了光纤传输带宽。另外通过插入一种并行扰码对图像数据进行伪随机码调制解调,提高了光纤串行传输的稳定性。仿真和测试表明:该技术在传输速率达到10.312 5 Gbit/s时,实际有效数据传输速率达到6.6 Gbit/s,传输系统稳定性高,可广泛应用于高清图像数据的远距离传输。

多专家注释的视杯和视盘不确定性量化

现有基于深度学习的视杯和视盘分割方法在模型训练时,仅使用图像的单个注释或从多个注释中获取唯一的注释信息,忽略原始多专家标注中嵌入的一致性或差异性信息,从而导致模型和预测结果过度自信等问题。提出一种基于多解码器不确定性感知体系的模型MUA-Net。通过引入专业知识推断模块,将各个专家注释的专业知识水平作为先验知识嵌入编码器和解码器的瓶颈中,以形成包含专家线索的高级语义特征。利用可同时学习多个注释的多解码器结构调节多专家之间的分歧,重构多专家注释过程,并对不确定或分歧区域进行量化。提出一种双分支软注意机制,增强多解码器分割预测的模糊区域,得到最终校准的分割结果。实验结果表明,该模型在RIGA数据集上能以较高的不确定性预测合理的区域,与MRNet模型相比,该模型在视杯分割中的平均精度、Dice系数、交并比分别提升了0.75、0.39、0.41个百分点。

新型冠状病毒感染后急性黄斑神经视网膜病变的多模影像学特征

目的探讨新型冠状病毒感染后出现的急性黄斑神经视网膜病变(AMN)的多模影像学特征。方法回顾性分析南昌大学第一附属医院感染新型冠状病毒后诊断为AMN的患者6例12眼,结合患者病史、临床表现、眼底照相、SD-OCT、OCTA、En-face结构图、眼底自发荧光(FAF)、红外成像(IR)、荧光素眼底血管造影(FFA)、多焦视网膜电图(mfERG)、视野等检查结果,综合分析AMN的多模影像学特征。结果6例患者中女4例,男2例;年龄16~30岁;发病时间3~15 d;2例4眼属于急性期AMN,4例8眼属于进展期AMN。4眼(33.3%)眼底黄斑区可见楔形棕红色病灶;12眼(100.0%)IR可见一个或多个楔形弱反射病灶;SD-OCT示8眼(66.7%)进展期AMN黄斑区视网膜局灶性椭圆体带、嵌合带断裂及缺失,4眼(33.3%)急性期AMN黄斑区视网膜外核层及外丛状层可见高反射病灶;8眼(66.7%)进展期AMN椭圆体带和嵌合带En-face结构图可见片状低反射病灶,4眼(33.3%)急性期AMN深层视网膜En-face结构图可见片状高反射病灶;4眼(33.3%)mfERG示黄斑中心凹一阶反应振幅密度稍降低;6眼(50.0%)视野检查可见一个或多个中心、旁中心暗点。FFA、FAF、OCTA检查均未见明显异常改变。结论新型冠状病毒感染后AMN患者多为青年人,急性发病,眼底改变不明显,多模影像学可实现对AMN的早期诊断。