超高精细度微光学腔共振频率及有效腔长的精密测量

超高精细度微共振器是实现原子或者其他偶极子与腔强耦合作用的基本部分, 在腔量子电动力学(QED)、弱光非线性效应及微光学器件研究中扮演着重要的角色. 微腔基本参数的精密测量最终可以确定腔与原子的耦合系数、腔场衰减率, 对决定系统的动力学特性具有重要的意义. 但是由于超高精细度光学微腔本身的构造和多层镀膜的特点, 高精度地确定其共振频率及有效腔长存在一定困难. 本文结合修正的多层介质膜模型, 实验上完成了膜层为37层的超高精细度光学微腔在不同共振频率下有效腔长的精密测量, 获得了超高精细度光学微腔的共振频率及波长; 理论计算分析与实验测量结果相符, 对纵模间隔的测量精度误差低于0.004 nm, 较为修正前提高了约两个量级. 同时给出了对应不同模式数下, 光波渗入到介质中的深度. 该方法可望应用到其他微共振器的精密测量中. 关键词： 光学微腔 高精细度 共振频率     

用晶体斜劈方法测量石英波片相位延迟的温度特性

介绍了一种基于晶体斜劈的偏振光相位延迟量的精密测量方法,并将该方法用于测量零级和多级石英波片相位延迟量的温度特性。该测量方法不受光源功率波动的影响,相位测量精度可以达到0.05°。相比于传统的测量方法,晶体斜劈方法在相位测量过程中无需调节光学元件,可以实时地测量相位变化,而且该方法可用于任意光学元件引入相位延迟的精确测量,或推广到不同的光学波段。     

一类多涡卷混沌吸引子及电路设计

提出了一种产生多涡卷混沌吸引子的方法并给出了相应的电路设计.该方法由若干个分段线性函数构成混沌系统的非线性函数,构造不同的分段数可以获得不同数量的涡卷混沌吸引子.数值仿真和EWB仿真结果表明了该方法的有效性. 关键词： 多涡卷混沌吸引子 分段线性函数 电路设计 电路实验结果     

高Q光学微球腔角速度传感效应验证

根据角速度传感的基本原理,搭建了以高Q光学微球腔为核心敏感部件的角速度传感实验测试系统。实验中通过调制、解调技术得到了光学微球腔的谐振曲线及其相对应的解调曲线,并采用PID反馈控制电路实现了微球腔谐振点的实时跟踪锁定,谐振点锁定精度约为10 kHz。通过对系统提供低、高2组不同的旋转角速度进行实验测试,并对数据进行处理分析,得到系统输出信号幅度的变化趋势与测试转台提供的旋转角速度变化情况相对应的结果。初步验证了高Q光学微球腔的角速度传感效应,为后续深入研究高Q光学微谐振腔角速度传感器件奠定了基础。     

用于位移精密测量的光外差马赫-泽德干涉仪

本文介绍了我们研制的用于位移精密测量的光外差马赫－泽德干涉仪。由于在光路设计中采用了共光路的布置，共模抑制技术得以实现，环境干扰产生的噪声得到很好的消除，相位检测的稳定性和精度大大提高。使用该干涉仪测量了一台在光学相移器内ＰＺＴ微位移驱动装置的电压－位移关系。测量结果具有良好的线性和重复性，与预期相符。根据测量数据分析，该光外差干涉仪具有３ｎｍ的位移测量精度。     

基于嵌入式的工业控制人机界面系统研究

针对工业控制系统网络化和良好人机交互性的需求,构建和开发了基于ARM9微处理器的通用工业控制人机界面系统。硬件部分主要讨论了以S3C2440微处理器为核心的硬件电路设计,外围电路模块包括SDRAM及Flash存储器电路、以太网电路、RS-232/RS-422电路、触摸屏及LCD接口等电路,在分析了硬件系统信号完整性的前提下,完成了6层PCB的设计工作。软件部分主要研究了U-Boot移植和内核裁剪技术,编写了相关的硬件设备驱动程序,设计了基于QT/Embedded的人机界面和相关应用程序。论文研究最终实现了工业控制系统的人机交互和控制需求。     

窄线宽激光在光学谐振腔腔长精密测量中的应用

提出了一种利用窄线宽激光作为测量光源,对光学谐振腔自由光谱区、腔内共振激光波长进行精密测量而得到光学谐振腔腔长的方法。对光学谐振腔腔长的测量理论进行了严格推导,通过理论模拟对测量条件及结果进行了分析讨论。以自行研制的线宽为1.9Hz、频率不稳定度为1.7×10-14 s-1、中心波长为1550nm的窄线宽激光作为光源,对长度约100mm的光学谐振腔腔长进行了精密测量。对光学谐振腔自由光谱区进行测量,得到其腔长为0.10024407m、精度为22nm;对光学谐振腔腔内共振激光波长进行测量,得到其腔长为0.1002440884m、精度为0.21nm,精度相对提高了2个量级。提出的方法有望促进基础物理研究、材料的物理属性精密测量及光纤传感等领域的发展。     

双光梳非线性异步光学采样测距中关键参数的数值分析

双光梳异步光学采样的绝对测距方法具有量程大、测速快和精度高等特点,在几何量精密测量领域具有广泛的应用前景.特别地,结合异步光学采样和非线性强度互相关的倍频信号时域探测方法,可以有效避免测量过程中载波包络偏移频率对测距精度的影响.本文针对双光梳非线性异步光学采样绝对测距系统,对影响其测距精度的理论模型和关键参数进行数值模拟研究.对双光梳异步光学采样的理论模型进行分析后,分别研究了双光梳光源参数(重复频率和重复频率差)、倍频信号精细拟合及脉冲时间抖动对测距精度的影响.数值分析结果表明:选择合理的重复频率和重复频率差有利于提升测距精度,此外适当提高测量速度可以有效降低脉冲时间抖动对测距误差的影响.     

油管位置光电检测技术的研究

本文提出了一种测量汽车油管位置的方法。该方法采用平行光投影的光学系统，以高分辨率面阵CCD成像，通过数字信号处理(DSP)系统进行图像采集与处理，处理速度快，可以实现实时处理。在图像处理中，采用合适的边缘检测方法，提高了测量精度。数据处理中采用了最小二乘法拟合曲线，可以精确的拟合出油管像的曲线。与理论曲线相比较，就可以有效地测量油管的位置。     

电调制非分光红外瓦斯传感系统设计

基于气体红外光谱吸收原理,设计了一款电调制非分光技术的红外瓦斯传感器系统.该系统采用单光路双波长技术,以红外LED光源IRL715、防尘防水的吸收气室和热释电探测器件LIM-262组成光学探头,利用有源滤波和差分放大电路实现信号调理,采用二项式拟合瓦斯浓度-电压关系曲线,实现了对瓦斯浓度的精确探测.实验表明,该传感器能...     

基于有限状态机的光存储伺服系统设计

采用有限状态机描述光存储伺服系统的状态转换过程。有限状态机通过CPLD硬件实现,以控制光学头的运动状态。根据DVD伺服标准的要求,设计超前滞后补偿器对整个伺服环路进行补偿。利用标准光学头和标准盘片对整个伺服系统进行了测试。测试结果表明,该伺服系统精度较高,聚焦精度小于10%,循迹精度小于20%,对于标准盘片能得到较高的Jitter(<8%)。     

基于DVD光头的双光子光致漂白三维光存储

基于现有的DVD光头物镜与音圈电机，根据光致漂白的双光子吸收气维光信息存储原理，以钛蓝宝石飞秒脉冲激光进行双光子光信息写入和读出，利用音圈电机进行选层，在新型光致漂白材料二苯乙烯衍生物中进行光致漂白二进制编码信息的存储和读出实验研究；实现了三层光信息存储，信息点间距和信息层间距分别为4μm和15μm；用Matlab软件读出信息的信号强度并对其进行了识别，识别结果与写入的二进制编码信息完全一致。实验证明了用DVD光头进行双光子三维光数据存储的可行性，表明双光子吸收光致漂白技术可以与现有CD／DVD兼容，为实现多层高密度和超高密度光信息存储打下基础。     

Fabrication and verification for the small-form-factor holographic optical pickup

In this investigation, a small-form-factor (SFF) pickup head with a holographic optical element (HOE) is fabricated. The system employs a finite-conjugate object lens to focus a light beam. A holographic optical element is used to simplify the optical configuration. It provides a better means of alignment of fabrication and reduces the size of system relative to reflective light route. Micro prisms are fastened with HOE and a silicon substrate, laser diode and photodiode are integrated into the optical system. The pickup head system based on discrete components and a flip chip bonder with highly accurate alignment was to integrate it. The micro holographic optical pickup head is fabricated and tested. Experimental results including the spot diameter and the focusing error signal (FES), demonstrate that the optical system is a feasible.     

An Advanced Signal Processing Technique Designed for Multilevel Signal Optical Disc System

We propose a novel signal processing technique by which we can increase the effective signal to noise ratio of optical discs. This technique is capable of reducing the influence of random noise even when the playback signal contains a distortion. We apply this signal processing technique to single carrier independent pit edge recording optical disc system. When a linear recording density of 0.2 μm/bit and a track pitch of 0.8 μm for an optical pickup is used in a DVD pickup (γ =635 nm, NA=0.6), the experimental results show that the system can obtain tangential and radial skew margins of ±0.5° and ±0.75°, respectively. From the experimental results, we estimate that the proposed method is capable of increasing the capacity of DVD by a factor of about 1.2.     

Silicon-based transmissive diffractive optical element

A silicon nitride (SiNx) membrane diffractive optical element (DOE) designed to exhibit beam-splitting and focusing behavior at visible wavelengths has been fabricated and tested. Since the fabrication process is based on silicon micromachining technology, the DOE is easily integrated with a laser diode chip and a photodiode chip on a silicon substrate to function as the hologram-laser-photodiode unit for use in the pickup head of a CD or DVD system. The SiNx film is deposited with low-pressure chemical-vapor deposition and the free-standing membrane is formed by KOH etching. The transmissive DOE showed a high diffraction efficiency (>20% for a binary-phase-level element). The experimental evaluation was in good agreement with the designed and modeled predictions.     

Movement dynamics analysis for an optical pickup head lens actuator in a digital versatile disc system

With the rapid development of CD/DVD(compact disc/digital versatile disc)technology,the disc rotation speed and the information density have increased greatly to fulfil the demand of high informatiopn bit rate transfer,As one of the most important elements in a DVD pickup head,objective lens actuators are required to provide a more precise means to accurately follow the disc deviation.The design of the lens actuator becomes all the more important and critical.In order to give complete suggestion to the design of the lens actuator,we put forward the movement differnetial equations as a new theoretical means to analyse the characteristics of the lens actuator reliably and rigorously.Based on the theoretical analyses,many important and effective methods are propsed.A typical experiment verifies that the performance of our lens actuator head,which adopts these methods,can satisfy the high speed and high density requirement of DVD systems.     

Fiber type of optical coherence tomography with an auto-focus device

Optical coherence tomography (OCT) is a novel technique for non-invasive imaging based on low coherence interferometer. In this study, we develop a new optical fiber type of OCT with a commercial auto-focus device to simultaneously measure the refractive index and thickness of a single-layer for demonstration. An auto-focus device can be easily implemented into the new OCT in order to diminish the measurement error resulting from the slight vibration of the sample and/or the sample stage. However, if the conventional OCT is implemented with an auto-focus device, it would be extremely difficult in locating and controlling the positions of the sample and scanning stages.From the experimental results, the error percentage from various frequency of the simulated noise is almost under 0.4%. Due to the resonance frequency of a DVD pickup head is around 40 Hz, the error percentage is apparently highest up to 1%; however still acceptable. It is concluded that the auto-focus device indeed works in an OCT system.     

Interferometry with optical pickups

We describe an interferometer that makes use of an optical pickup. This widespread consumer electronics component has a high degree of technological content. A typical head contains a remarkable, highly integrated sample of optoelectronic laboratory equipment. The application that we report is a significant and novel example of the potential exploitation of the unique features of such a device for scientific aims. Many interferometric configurations can be envisaged, depending on the specific pickup design. We present a Fizeau multiphase homodyne interferometer that makes use of an astigmatic-focus-detection pickup. Its quadrant detector provides four photocurrent signals whose phase delays can be easily controlled. This allows us to apply phase-shifting interferometry algorithms for data reduction.     

Resolution enhancement in a reflection mode near-field optical microscope by second-harmonic modulation signals

The motion of the probe tip in a near-field scanning optical microscope, dithered by vibration of a tuning fork, can modulate the reflection signal from the sample surface not only at the fundamental dithering frequency but also at its second harmonic. By lock-in amplification of these modulated signals, enhanced optical images are obtained, even with an uncoated fiber probe. In particular, accurate optical images with higher resolution are obtained when the second-harmonic signal is detected, which results from the parametric modulation of the tip-sample separation at the double frequency of the horizontal dithering motion of the tip. Using a DVD ROM with a track pitch of 0.74 mum as a test sample, we observed that the sharp edges around the pits are clearly resolved with the second-harmonic signals and obtained enhanced resolution of ~70 nm full width at half-maximum.     

Dual frequency probe based coherent optical time domain reflectometry

A new approach to enhance the performance of coherent optical time domain reflectometry(C-OTDR) is proposed. In this approach, single frequency light is converted to multi-frequency light using phase modulator (PM), while only two frequencies with the same light power level are adopted as the probe .Coherent heterodyne between the dual frequency probe and original single frequency local oscillator (LO) generates the same intermediate frequency (IF), which equals two IF signals automatically synthesizing in the process of coherent detection other than in IF signal processing circuit, so it doubles measurement speed. Experimental results show that compared with conventional single frequency probe based C-OTDR the dual frequency probe based C-OTDR has more quickly coherent Rayleigh noise (CRN) reduction capability and can bring a 3.0 dB dynamic range improvement.