High-gain and low-distortion Brillouin amplification based on pump multi-frequency intensity modulation

Using a pump with a multi-line spectrum to broaden the Brillouin gain bandwidth is an effective way to achieve lowdistortion amplification with high gain. Here, we theoretically and experimentally investigate the generation of a broadband Brillouin gain spectrum based on multi-frequency intensity modulation in an optical fiber. The arbitrary bandwidth of the Brillouin gain spectrum of stimulated Brillouin scattering(SBS) can be obtained as expected. In our experiment, a broadband Brillouin gain spectrum with a bandwidth of about 200 MHz is demonstrated. We also achieve a low-distortion amplification of a weak signal, whose maximum magnification is 65 d B for a-68-dBm input power signal.

A Theoretical Evaluation of Optical Parametric Amplification in BBO Crystal

The noncollinear optical parametric amplification in BBO crystal is theoretically investigated. The phase matching angle, gain bandwidth, optimal noncollinear angle and conversion efficiency for both type-I and type-II BBO are simulated. The numerical simulation results are important to the practical optical parametric amplification experiments with BBO crystal.

Image Enhancement in Coherent Optical Amplification by Photorefractive Crystals

In this paper, a model of two-wave mixing in the photorefractive crystal, which takes account of the difference in spatial frequency in a beam, has been built to study the image enhancement effect in coherent optical amplification. Based on the theoretical analysis of the model, the gain distribution for each pixel in the signal beam has been obtained. It shows that the unevenness of the gain is induced by the difference in spatial frequency in the beam. The factors that impact on the uniformity of image enhancement have been analyzed. As an example, the effects of these factors in a given photorefractive crystal have been studied through simulation.

全光纤自相似锁模激光器实验及理论研究

在锁模光纤激光器中,本研究基于高集成度器件同时实现了泵浦耦合、光谱滤波和偏振相关隔离损耗,进而在1550 nm波段实现了自相似被动锁模脉冲输出。同时还搭建了全光纤放大器进行非线性增益管理放大,成功将自相似脉冲的10 dB谱宽从25.9 nm拓宽至52.6 nm,然后利用负色散光纤将脉冲宽度压窄至66 fs。最后,基于广义非线性薛定谔方程与激光速率方程的数值模拟,从理论上研究了激光器和光纤放大器的脉冲运转过程。模拟结果表明腔内的窄带滤波器和较长的正色散增益光纤是线性啁啾自相似锁模脉冲产生的必要条件,当自相似脉冲被光纤预压缩后,使用足够长度的正色散增益光纤可同时实现脉冲的自相似放大以及非线性增益管理放大,从而在全光纤结构中输出脉宽小于100 fs的锁模脉冲。

The giant enhancement of Fano-type resonance in a gain-assisted silicon slab array

Giant resonance enhancement is demonstrated to be due to the Fano interference in a grating waveguide composed of gain-assisted silicon slabs. The Fano mode is characterized by its ultra-narrow asymmetric spectrum, different from that of a pure electric or magnetic dipole. The simulation indicates that a sharp Fano-interfered lineshape is responsible for the giant resonance enhancement featuring the small-gain requirements.

Optimization control of modulation-instability gain in photonic crystal fibres with two zero-dispersion wavelengths

We design three kinds of photonic crystal fibres （PCF） with two zero-dispersion wavelengths （ZDWs） using the improved full vector index method （FVIM） and finite-difference frequency domain （FDFD} techniques. Based on these designed fibres, the effect of fibre structure, pump power and wavelength on the modulation instability （MI） gain in the anomalous dispersion region close to the second ZDW of the PCFs is comprehensively analysed in this paper. The analytical results show that an optimal MI gain can be obtained when the optimal pump wavelength （1530 nm） is slightly shorter than the second ZDW （1538 nm） and the optimal pump power is 250 W. Importantly, the total MI gain bandwidth has been increased to 260 nm for the first time, so far as we know, for an optimally-designed fibre with ∧ = 1.4 nm and d/∧ = 0.676, and the gain profile became much smoother. The optimal pump wavelength relies on the second ZDW of the PCF whereas the optimal pump power depends on the corporate operation of the optimal fibre structure and optimal pump wavelength, which is important in designing the most appropriate PCF to attain higher broadband and gain amplification.

An easily-prepared impedance matched Josephson parametric amplifier

An impedance matched parametric amplifier(IMPA)with Josephson junctions is fabricated and characterized.A hybrid structure containing coplanar and strip structures is implemented to realize an impedance taper line and a plate capacitor in an LC nonlinear resonator based on Josephson junctions.The upper plate of the capacitor is isolated with SiNx without grounding as well as the strips.Such easily-prepared designs greatly reduce the requirements for lithography alignment and precision,which makes the fabrication process more reliable.The experimental results show that in such IMPA a gain higher than 25 dB with a bandwidth of about 100 MHz can be obtained.This broadband amplifier operates close to the quantum limit.By adjusting the working point,a higher bandwidth of about 400 MHz can be obtained with a gain of about 17 dB.

用于多模态非线性光学显微成像的增益管理放大全光纤飞秒激光技术

基于增益管理非线性放大的机制,求解非线性薛定谔方程和速率方程对脉冲在增益光纤中的传播过程进行仿真,研究了脉冲在增益光纤中的演化过程。结果表明,优化预啁啾量和种子光强度,可改变脉冲在增益光纤中的增益曲线。在动态增益曲线与非线性效应的共同作用下,输出光脉冲的频谱会迅速展宽数倍并带有线性啁啾,进而脉冲可被压缩至近傅里叶变换极限。为验证该超短脉冲产生方式的可行性,采用仿真结果中的最佳参数设置,成功设计并搭建了一台高能量、短脉宽、高质量的超快光纤光源。该光源可实现中心波长为1060 nm、重复频率为35 MHz、平均功率为267.4 mW以及脉冲宽度仅为39.5 fs的激光输出,与仿真结果高度一致。同现有的超短脉冲产生方式相比,本实验装置的结构更简单、造价更低、装置更紧凑、产生光束品质更佳。

AlGaN/GaN HEMT小信号放大电路设计及放大增益预测

采用计算机辅助设计技术(TCAD)对AlGaN/GaN高电子迁移率晶体管(HEMT)器件进行了仿真,并利用Multisim设计了AlGaN/GaN HEMT器件的低频小信号放大电路.由于GaN材料的宽带隙和高载流子迁移率,HEMT器件可以在空间科学应用中取代Si基MOSFET.TCAD的仿真结果通过与测试结果的比较进行了修正.通过Multisim仿真结果与搭建的AlGaN/GaN HEMT共源共栅放大电路的测试结果对放大电路的放大特性进行了验证.以此为基础,利用TCAD模拟改变了结构参数的器件特性并采用改进了结构参数的AlGaN/GaN HEMT设计共源共栅放大电路.仿真结果表明,该放大电路在低频和室温下的电压放大能力可达6 200倍.

自适应增益光电探测电路设计

在激光模拟实兵对抗系统中,为解决传统光电探测电路受环境影响大,系统不稳定、检测效能低的问题,设计了一种基于单片机的增益自适应光电探测电路。在传统光电探测电路的基础上改用两个对称分布的跨阻放大反馈电路,消除光电探测器偏置分量,抑制前置放大电路的系统噪声;采用自动增益控制电路使不同射击距离下输出信号幅值保持稳定;采用多级滤波的方式去除信号的直流分量并有效抑制背景噪声,为信号的进一步处理提供准备。通过实验验证与TINA-TI仿真分析结果表明,该光电探测电路可以实现增益自适应变化,在不同入射距离下输出电压幅值基本稳定在2V左右。其性能明显优于传统固定增益电路,极大地提高了对光电信号的探测能力,该结果验证了本文提出的光电探测电路设计的科学性和可行性。

全国产化微弱信号调理电路

为更好地处理微弱信号,提出一种新型的多通道信号前端调理模块。该模块不仅具有可编程增益功能,而且还整合了带通滤波器。在保证高输入阻抗和低噪声等关键性能的同时,提出一种全面而创新的调理模块设计方案。该方案的核心是采用可编程增益放大电路,显著提高了模块在放大各类微弱信号时的适应性。此外,利用HC595系列芯片,实现了对增益的精确调控。该放大电路具备26 dB的固定增益和0~84 dB的可调增益范围,工作带宽设定在380~420 kHz。经过系统性能测试,结果表明该调理电路成功满足了设计目标的各项要求。

高峰值功率GMN飞秒光纤激光器研究进展(特邀)

高峰值功率飞秒光纤激光器在高精度工业制造、生物医学、国防、航空航天等领域有着广泛的应用。目前,产生高峰值功率飞秒光纤激光的主要方法是啁啾脉冲放大技术和非线性脉冲放大技术,然而前者虽然能够产生单脉冲能量大于1 mJ的飞秒脉冲,但受限于增益窄化效应,产生的脉冲持续时间通常大于200 fs。后者虽然能够产生持续时间~50 fs的脉冲,但整体设计比较复杂,限制了其应用范围。随着国内外相关工作的长期积累以及激光器件等硬件能力的提升,科研人员提出了一种基于增益管理非线性(Gain-Managed Nonlinear,GMN)放大的方案,这项技术能够以简单的系统设计产生持续时间小于50 fs的脉冲,还能保证紧凑的系统结构。综述了增益管理非线性放大技术的理论研究进展,总结了国内外不同设计结构的增益管理非线性放大系统研究进展,最后对增益管理非线性放大系统的应用进行了展开分析,展望了其在未来的发展方向。进一步分析了泵浦波长、泵浦方式对增益管理非线性放大的影响,提出了一种全光纤一体化的增益管理非线性放大系统,并利用该系统进行了超连续谱产生的应用研究。

一种基于0.18 um工艺的高增益CMOS运算放大器

高增益CMOS运算放大器在集成电路设计中扮演着重要角色。CMOS运算放大器具有高增益特性,能够放大微弱的信号,并在电路中提供稳定的放大功能。提出了一种新型高增益CMOS运算放大器的设计方案,由4个三端NMOS管和4个三端PMOS管共同构成,通过优化电路结构和参数配置,结合了负反馈和级联放大器的优势,实现了较高的增益和性能指标。该运算放大器采用0.18 um CMOS工艺设计,仿真结果表明,在电压为1.8 V,负载电容为60 pF的环境下,该运算放大器的开环直流增益为81dB,增益带宽为110 M H z,相位裕度为72.9°,电源抑制比110 dB,电源总功耗仅为55 uW。大大提升了运放的增益,降低了电路的功耗并节省了面积。

Light gain amplification in microcavity organic semiconductor laser diodes under electrical pumping

Organic semiconductor is one of the most promising luminescent and lasing materials that can be chemically synthesized with a controllable performance and possess high cross-section of stimulated emission . Organic semiconductor laser diodes （OSLDs） can be prepared by simple processing technologies and integrated easily with other optoelectronic devices. As a result, OSLDs would have appealing applications in low cost, compact, flexible and tunable lasers with spectral region from ultraviolet to near infrared . Although lasing has been widely demonstrated under optical pumping, electrically pumped OSLDs are rather difficult to realize because the expected high threshold current is hard to reach in low electrical conductivity organic semiconductors and electroluminescence （EL） efficiency is much decreased under high current.

一种24~27 GHz共源共栅高增益低噪声放大器设计

基于40 nm CMOS工艺,设计了一款高增益的低噪声放大器芯片。该芯片的拓扑架构采用了变压器输入匹配技术和正反馈同相放大技术,以提高输入匹配程度和增益。通过在传统共源共栅结构的输入级引入有源偏置网络及变压器匹配网络,实现的芯片在仿真环境下不仅能够在常温条件下稳定工作,还展现出-40℃~125℃范围内的优越性能。因此,该设计可用于不同温度环境下毫米波频段的收发机接收端口,并且有着一定的温度稳定特性。该低噪声放大器芯片的版图尺寸为0.383 mm×0.694 mm。版图后仿真结果显示,在24~27 GHz的工作频段内,该低噪声放大器常温下实现了低于4.96 d B的噪声系数、18.11 d B的最大增益、小于-16.08 d B的输入回波损耗和小于-11.54 d B的输出回波损耗。此外,该低噪声放大器设计还具有输入P_(1dB)为-20.36 d Bm、直流功耗P_(diss)为12.8 m W等优异指标。

基于增益腔的腔磁力混合系统中的光放大和快慢光传播

为了在腔磁力系统中实现可控的磁子诱导透明、磁力诱导透明、光放大以及快慢光传播,建立了一个腔磁力混合系统模型.该模型由含有1个钇铁石榴石(YIG)球的增益腔组成.该模型利用强驱动来驱动YIG球,利用弱探测场探测微波腔.研究表明,通过选取最优增益和调节腔-磁耦合强度、磁-力耦合强度可以实现可控的磁子诱导透明、磁力诱导透明、光放大以及快慢光传播.该研究结果可为量子信息操纵、量子信息存储和灵敏光开关的研究提供参考.

无源光网络中的信号放大与传输增益优化

文章论述无源光网络(Passive Optical Network,PON)的应用场景与挑战,探讨光纤放大器、半导体光放大器等信号放大技术在不同场合下的表现和效果,提出优化放大器参数配置、信号预调制与补偿技术、网络拓扑结构优化策略、噪声抑制与信号净化技术等优化策略,以期全方位提升无源光网络系统的性能表现。

高增益高带宽电子探测互阻放大电路研究

互阻放大电路作为前置放大器,在光通信、红外测量、半导体量测设备等领域应用广泛,但是其增益与带宽等动态可靠性的自相矛盾一直是困扰其高速应用的难题。吞吐量一直是困扰SEM系统的重大瓶颈之一,高速电子探测前置放大电路对于获得高吞吐量的扫描电子显微镜系统至关重要。本文利用专业仿真软件模拟分析了研究高速互阻放大电路的动态稳定性,说明了米勒补偿电容以及电子探测器等效输入电容对系统动态特性的影响,最终设计出增益高达20kΩ带宽超过12MHz的高动态稳定性的互阻放大电路。

水下磁通信系统研制与调试

文章研究水下磁感应通信技术,旨在为海洋资源开发和环境监测提供一种有效的通信手段。通过对水下磁场特性的分析,设计了磁通信系统,包括发射电路、接收电路以及收发天线。系统采用调幅信号,通过功率放大电路提高发射功率,同时设计了自动增益控制电路以适应不同通信距离。实验在一个80 cm×80 cm×30 cm的玻璃水缸中进行,使用1.6 MHz正弦波信号激励发射线圈,通信距离为0.1~1.0 m。实验结果表明,水介质的导电特性使得水下通信传输距离比空气中更远,但随着涡流损耗的增加,系统的能量损失变得更加明显。

A Distributed Time-Variant Gain Hydrological Model Based on Remote Sensing

提出了一个完全采用遥感数据驱动的分布式时变增益水文模型,该模型通过融雪、产汇流等水文过程计算,给出流量的雪盖、蒸散发、径流等水文要素。在拉萨河流域,该模型采用遥感USGS-SRTM的3秒DEM、遥感TRMM(The Tropical RainfallMeasuring Mission)降水、Modis-LST(Land Surface Temperature)数据,建立分布式水文模型,模拟了2001-2008年日水文过程。模拟结果效率系数接近0.7,相关系数接近0.8,水量平衡误差5%以内。说明完全依靠遥感驱动水文模型进行水文水资源模拟可行。该模型为解决高寒山区无资料或缺资料地区水文水资源问题提供了一个新方法。