Transmission Characteristic Simulation of High Frequency Acousto-Optic Modulators

The way by which one can make sure the operating mode of the modulation is by observing the Comsol results of the designed model of proposed acousto-optic modulator (AOM). These results include the pressure distribution, sound pressure distribution, stress distribution at piezoelectric, far-field analysis that describes the diffracted light orders, and electric potential versus light frequency. Throughout the simulating process of modulator operating using Comsol, it begins when the RF is power by a voltage of 100 V, the light is then split into first ordered diffraction, which implies that the modulator is in the operating mode. The use of semiconductor materials is due to its smaller gap that easily transfers the energy that leads to generating first order diffraction when they provided a voltage power. It mentioned that zero order diffraction indicates the modulator does not run;other orders are appearing with increasing the frequency of light leading to decrease of the efficiency of the modulator performance.

Acousto-optic modulator-based bi-frequency interferometer for quantum technology

We demonstrate a high-performance acousto-optic modulator-based bi-frequency interferometer,which can realize either beating or beating free interference for a single-photon level quantum state.Visibility and optical efficiency of the interferometer are(99.5±0.2)%and(95±1)%,respectively.The phase of the interferometer is actively stabilized by using a dithering phase-locking scheme,where the phase dithering is realized by directly driving the acousto-optic modulators with a specially designed electronic signal.We further demonstrate applications of the interferometer in quantum technology,including bi-frequency coherent combination,frequency tuning,and optical switching.These results show the interferometer is a versatile device for multiple quantum technologies.

VR光学模组镜片粘接用UV胶的选型研究

环烯烃共聚物(COC)常应用于VR产品镜片,具有低吸水率、超低应力的特点,然而COC材料的粘接难度高,对此类粘接问题的研究较少。为了更好地研究VR光学模组中UV胶选型的关键因子,本研究针对VR光学模组结构与Pancake镜片COC材质的特点,通过模拟VR光学模组的应用环境,在实验室设计了高温高湿、温度冲击两个关键条件。选取30款(G1~G30)市售不同厂家的UV胶水,检测了不同热膨胀系数、玻璃化转变温度(Tg)、韧性、低温下储能模量的胶水组装的模组在这些模拟条件下的耐久性能,并通过分析UV胶常温断裂伸长率、Tg等相关参数探究其与最终粘接效果的关系,以期为COC材质的镜片粘接胶水的实际选型和应用提供参考。研究结果表明:通过探究UV胶热膨胀系数、Tg点、韧性、低温下储能模量等4个关键因子,发现G2和G3含有零上和零下两个Tg点、低温下储能模量低(小于1000×10^(6) Pa),并具有较好的韧性(断裂伸长率大于400%,杨氏模量小于60×10^(6) Pa),可以抵抗冷热温度冲击,推力与光学性能表现良好。G2和G3可维持VR模组光学成像的稳定,并解决VR模组温冲试验中胶水开裂问题。本文为COC材质粘接的胶水提供一种可行的选型依据,在实际生产中有一定的指导意义。

Spectral analysis of the UFBG-based acousto optical modulator in V–I transmission matrix formalism

In this study, the V-I transmission matrix formalism （V-I method） is proposed to analyze the spectrum characteristics of the uniform fiber Bragg grating （FBG）-based acousto--opfic modulators （UFBG-AOM）. The simulation results demon- strate that both the amplitude of the acoustically induced strain and the frequency of the acoustic wave （AW） have an effect on the spectrum. Additionally, the wavelength spacing between the primary reflectivity peak and the secondary reflectivity peak is proportional to the acoustic frequency with the ratio 0.1425 nm/MHz. Meanwhile, we compare the amount of calculation. For the FBG whose period is M, the calculation of the V-I method is 4 × （2M-l） in addition/subtraction, 8 × （2M - 1） in multiply/division and 2M in exponent arithmetic, which is almost a quarter of the multi-film method and transfer matrix （TM） method. The detailed analysis indicates that, compared with the conventional multi-film method and transfer matrix （TM） method, the V-I method is faster and less complex.

Serrated periodic electrode for high energy efficiency and large bandwidth acousto-optic modulators

In an acousto-optic modulator,the electrode shape plays an important role in performance,since it affects the distribution of the acoustic field.The acousto-optic modulator based on the conventional rectangular electrode has the problems of low energy efficiency and small modulation bandwidth due to an imperfect acoustic field.In this paper,a new serrated periodic electrode has been proposed for using acousto-optic modulator transducers.The proposed electrode has the following advantages.By using serrated periodic electrodes to suppress the sidelobes,the collimation of the acoustic field in the direction perpendicular to the light incidence is improved.This makes the acousto-optic modulator have a stable diffraction efficiency fluctuation and high energy efficiency.In addition,the electrode has a large divergence angle in the direction of light incidence,so a large bandwidth can be obtained.The simulations and experiments demonstrate that the serrated periodic electrode has an increased bandwidth and high energy efficiency.

Acousto-optic Devices: Theory and Applications

The basics and applications of acousto-optic devices are described.The applications include acousto-optic spectrum analyzer,acousto-optic deflector,acousto-optic processors and acousto-optic digital matrix computer.

Mid-infrared lightly Er^(3+)-doped CaF_(2)laser under acousto–optical modulation

A 1.7-at.%Er:CaF_(2)crystal was synthesized by temperature gradient method.The Er:CaF_(2)crystal was applied in acousto-optically Q-switched laser at mid-infrared region for the first time.Using a Te O_(2)-based crystal as Q-switcher,we obtained a laser diode(LD)end-pumped Er:CaF_(2)laser with the highest single pulse energy up to 0.49 mJ and maximum peak power of 0.56 kW under 6.34-W absorbed pump power.The implication of these results is that the low-doped Er:CaF_(2)crystal exhibits promising optical properties in solid-state lasers.

深水AUV安全系统的设计与实现

安全性是自主式水下机器人(AUV)系统研究的重要内容。为解决传统设计只能对预先估计和实时监测故障做出反应等问题,依托实体深水AUV,设计出一套新的安全系统,构建主控单元和应急模块的安全冗余结构。主控单元选用基于PC/104总线的工控机设计,应急模块采用C8051F410设计。大量模拟故障仿真实验和AUV实际下水实验表明,该安全系统不仅扩大了故障或危险的应对范围,而且将各应急情况下AUV的抛载执行率提高至100%,可有效保障AUV系统的安全。

可调式UVB自动控制系统的研制

我们在中国科学院千烟洲生态网络实验站建立了国内一个可调式UV-B辐射自动控制系统,用于模拟研究水稻对一定比例的地表UVB增强的反应。该系统能够根据阳光中UVB辐射强度的变化而自动增加和减少人工光源输出的UV-B辐射强度,介绍了该系统的原理、结构及观测与控制效果。

PLC与文本显示器在UV机中的应用

介绍了UV机的制造过程及控制方法,利用LG的Master-K120系列PLC作为UV机的主控制器,同时阐述了PLC(附加RTC模块)和文本显示器之间通讯原理。PLC与文本显示器取代原本的MCU与LCD的控制,不但减少了开发周期,并降低了成本,具有良好的应用市场前景。

人工增加UV-B辐照改善温室番茄品质

利用小型研究型温室,人工增加UV-B(紫外线B),旨在探讨增加UV-B辐射对改善温室番茄果实活性物质含量、提高番茄营养健康性能和商品品质的可行性,为温室生产提供参考。试验结果表明,适度增加UV-B辐照后,番茄节间长度缩短,株高降低。但植株结果节数增加,番茄果实数量增多,果实体积略有减小。UV-B辐射诱导花青素、黄酮类化合物等次生代谢物质的积累,刺激果实抗氧化能力和抗氧化活性的提升。因此,温室适量增加UV-B辐射,能提高番茄的营养物质,改善温室番茄果实品质。

一种基于UV-ESA自校准和高精度的PM电学测量方法

电光相位调制器(Phase Modulator,PM)因无需偏置,线性调制和插损小等优点,被广泛应用于相干光通信、微波信号产生、处理和测量等领域.调制指数和半波电压是评估PM性能的关键参数.传统基于(Optical Spectrum Analyzer,OSA)的方法面临测量分辨率低和存在测量盲区问题.为此,本文提出了一种基于电谱分析(Unequal Voltage based on Electrical Spectrum Analyzer,UV-ESA)的自校准、高精度的PM特性参数测量方法.该方法利用同频、不同驱动电压比的情况下,通过分析失谐光学载波和调制边带分别与载波拍音电谱,实现PM调制指数和半波电压的高频特性参数测量.该方法不需改变测量链路结构,无需辅助宽带微波源或电光调制器,验证了所提方法的有效性,并对比OSA方法对结果的准确性进行了验证.

Research and development of VUV optical coatings for micro mirror applications

This paper deals with vacuum UV optical coatings for micro mirror applications. High reflecting low-stress optical coatings have been developed for the next-generation of micro mechanical mirrors. The optimized metal systems are applicable in the VUV spectral region and can be integrated in the technology of MOEMS, such as spatial light modulators (SLM) and micro scanning mirrors.

Subnanosecond KTiOPO4 optical parametric oscillator intracavity pumped by a Kerr-lens, mode-locked YVO4/Nd:YVO4 laser coupled with an acousto-optic modulator

A Kerr-lens, mode-locked YVO4∕Nd:YVO4laser coupled with an acousto-optic modulator（AOM） Q-switching near1064 nm was employed to pump an intracavity KTi OPO4（KTP） optical parametric oscillator. A subnanosecond signal wave near 1572 nm with low repetition rate was realized. At an AOM repetition rate of 8 kHz, the maximum output power was 165 mW. The highest average pulse energy, the shortest duration, and the highest peak power of a mode-locking signal pulse were estimated to be ～10.3 μJ, ～120 ps, and ～82 kW, respectively.

All-fiber acousto-optic modulator based on a cladding-etched optical fiber for active mode-locking

An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the short length of the cladding-etched fiber, the ends of which are fixed on a slide glass. On top of the cladding-etched fiber, a piezoelectric transducer was overlaid. A chemical wet-etching technique, which is based on a mixed solution of NH_4F and (NH_4)2SO_4, is used to reduce the fiber diameter down to ～25 μm, and the length of the etched section is only 0.5 cm. The fabricated device exhibited a modulation depth of 73.10% at an acoustic frequency of 918.9 kHz and a peak-to-peak electrical voltage of 10 V, while a laser beam was coupled at 1560 nm.By using the prepared AOM within an erbium-doped-fiber ring cavity, the mode-locked pulses with a temporalwidth of 2.66 ps were readily obtained at a repetition rate of 1.838 MHz.

UVC-LED过流式饮用水消毒装置的理论分析及光学模拟

过流式饮用水消毒尤其是对大流量水处理时主要使用汞灯,使用UVC-LED作为杀菌光源的主要是小流量水处理的设备,随着UVC-LED灯珠技术上的不断突破,大流量水处理设备也在向UVC-LED靠近。介绍了一种UVC-LED过流式饮用水消毒装置理论模型,通过模组杀菌腔的接续杀菌,可以实现大流量流动饮用水消毒。根据光学模拟结果分析,单个模组杀菌腔的理论处理流量可以达到6 L/min。

基于氧化镓探测器的日盲紫外光通信系统的设计与实现

为克服传统光电探测器工作电压较高、硬件电路复杂与抗干扰能力差的问题,设计了一种基于新型氧化镓探测器的日盲紫外光通信系统。该系统在给定窗口大小的情况下,根据设计的数据处理算法对光强进行实时动态监测,通过将计算得到的阈值与光强作比较输出二值信号,结合OOK调制技术、驱动电路与非相干解调技术,实现了日盲紫外光通信系统。进一步从调制技术、驱动电路以及数据处理算法三个方面对通信系统进行仿真与实验测试,验证该系统的功能完整性、系统简洁性与可靠性。结果表明:该日盲紫外光通信系统在准确接收信号的情况下,可以直接实现将光强值转化为二值信号输出,且误码率小于10-3,能够达到简化接收端硬件电路以及提升硬件电路可靠性的目的。该系统编码简单可靠、易实现且抗干扰能力强,无需滤波装置、小巧便携、可靠性高,为日盲紫外光通信系统的优化与便携使用提供了新思路。

Acousto-optical modulation of thin film lithium niobate waveguide devices

Due to its strong piezoelectric effect and photo-elastic property, lithium niobate is widely used for acousto-optical applications. However, conventional bulk lithium niobate waveguide devices exhibit a large footprint and limited light–sound interaction resulting from the weak guiding of light. Here, we report the first acousto-optical modulators with surface acoustic wave generation, phononic cavity, and low-loss photonic waveguide devices monolithically integrated on a 500 nm thick film of lithium niobate on an insulator. Modulation efficiency was optimized by properly arranging the propagation directions of surface acoustic waves and optical guided modes.The effective photo-elastic coefficient extracted by comparing the first and third harmonic modulation signals from an on-chip Mach–Zehnder interferometer indicates the excellent acousto-optical properties of lithium niobate are preserved in the thin film implementation. Such material property finding is of crucial importance in designing various types of acousto-optical devices. Much stronger amplitude modulation was achieved in a high Q(>300,000) optical resonator due to the higher optical sensitivity. Our results pave the path for developing novel acousto-optical devices using thin film lithium niobate.

紫外LED调制特性研究

与低压汞灯相比,紫外LED具有体积小、寿命长、低压供电等特点,广泛应用于杀菌消毒、生物分析/检测等领域。介绍了紫外LED在紫外光通信领域的国内外发展现状,对紫外LED的调制速率及调制光谱进行了测试。实验结果表明,紫外LED调制速率可达10 MHz,调制状态下相对光谱与直流状态相吻合。实验数据可为紫外LED在紫外光通信中的应用提供理论依据。

紫外光通信调制方式的对比研究

紫外光非视距通信是一种新型的无线光通讯形式,近年来受到各军事强国越来越广泛的关注。详细分析了启闭键控调制(OOK)、脉冲位置调制(PPM)、差分脉冲位置调制(DPPM)和数字脉冲间隔调制(DPIM)的编码结构,然后从带宽需求、平均发射功率、传输容量和差错性能等方面对各种调制方式进行了仿真对比。结果表明,DPIM调制比PPM具有更高的传输容量和更少的带宽需求,并且解调对同步要求较低,实现更简易,并结合紫外LED阵列将作为今后实用化紫外光源的发展趋势,DPIM调制在未来紫外光通信系统的应用中将具有更大的优势。