Beam current enhancement of microwave plasma ion source utilizing double-port rectangular cavity resonator

Microwave plasma ion source with rectangular cavity resonator has been examined to improve ion beam current by changing wave launcher type from single-port to double-port. The cavity resonators with double-port and single-port wave launchers are designed to get resonance effect at TE-103 mode and TE-102 mode, respectively. In order to confirm that the cavities are acting as resonator, the microwave power for breakdown is measured and compared with the E-field strength estimated from the HFSS (High Frequency Structure Simulator) simulation. Langmuir probe measurements show that double-port cavity enhances central density of plasma ion source by modifying non-uniform plasma density profile of the single-port cavity. Correspondingly, beam current from the plasma ion source utilizing the double-port resonator is measured to be higher than that utilizing single-port resonator. Moreover, the enhancement in plasma density and ion beam current utilizing the double-port resonator is more pronounced as higher microwave power applied to the plasma ion source. Therefore, the rectangular cavity resonator utilizing the double-port is expected to enhance the performance of plasma ion source in terms of ion beam extraction.     

On-chip integration of high-frequency electron paramagnetic resonance spectroscopy and Hall-effect magnetometry

A sensor that integrates high-sensitivity micro-Hall effect magnetometry and high-frequency electron paramagnetic resonance spectroscopy capabilities on a single semiconductor chip is presented. The Hall-effect magnetometer (HEM) was fabricated from a two-dimensional electron gas GaAsAlGaAs heterostructure in the form of a cross, with a 50 x 50 microm2 sensing area. A high-frequency microstrip resonator is coupled with two small gaps to a transmission line with a 50 Omega impedance. Different resonator lengths are used to obtain quasi-TEM fundamental resonant modes in the frequency range 10-30 GHz. The resonator is positioned on top of the active area of the HEM, where the magnetic field of the fundamental mode is largest, thus optimizing the conversion of microwave power into magnetic field at the sample position. The two gaps coupling the resonator and transmission lines are engineered differently--the gap to the microwave source is designed to optimize the loaded quality factor of the resonator (Q相似文献   

High-power CO(2) laser-beam monitor

A diagnostic system for measuring the beam power and quality of a high-power cw CO(2) electro-aerodynamic laser is described. A ZnSe beamsplitter was employed to split off a small fraction (0.5%) of the main laser beam for diagnostic purposes. The low-power beam was split again to provide two beams for power and energy-distribution measurements, concurrent with sample irradiation by the main beam. An electrically calibrated disk calorimeter was used to measure beam power. The temporal and spatial energy distributions were measured by means of a mechanically scanned, one-dimensional pyroelectric array. This provided a 16x16 element two-dimensional map of the beam profile at a rate of up to 10 Hz.     

A piezoelectric resonator for optical power measurement with radiation beam quality retaining

A method for measuring the power of laser radiation in a wide range of wavelengths is introduced. The method is based on weak heating of an optically transparent piezoelectric resonator through which laser radiation is transmitted. After passing through such a resonator, the beam quality of laser radiation remains unchanged and the optical power can be utilized in laser technologies.     

Opto-acoustic phenomena in whispering gallery mode resonators

Optical whispering gallery mode resonators are important platforms to enhance and study various nonlinear frequency conversion processes. Stimulated Brillouin scattering is one of the strongest nonlinear effects, and can be successfully investigated using these platforms. In this article, we study the phenomenon of stimulated Brillouin scattering using a crystalline disk resonator. A fast scanning ringdown spectroscopy technique is used to characterize the optical modes featuring quality factors of the order of one billion at telecom wavelengths. The mW scale threshold power in a centimeter disk resonator is observed and found to be strongly dependent on the gap between the resonator and the prism coupler.     

微机械氮化硅梁谐振式压力传感器

报导一种新型的电热激励、压阻拾振的氮化硅梁谐振式压力传感器。器件采用微电子机械加工技术和键合技术研制。谐振频率85kHz,空气中品质因素Q值接近1000,在真空中达到40000。采用闭环自激振荡方式测定压力传感器的压力特性,压力测试范围0－400kPa,灵敏度23．8Hz/kPa。     

Tapping-mode tuning-fork near-field scanning optical microscopy of low power semiconductor lasers

The newly developed inverted tapping-mode tuning-fork near-field scanning optical microscopy (TMTF-NSOM) is used to study the local near-field optical properties of strained AlGaInP/Ga_0.4In_0.6P low power visible multiquantum-well laser diodes. In contrast to shear-force mode NSOM, TMTF-NSOM provides the function to acquire the evanescent wave intensity ratio | I (2ω)|/| I (ω)| image, from which the evanescent wave decay coefficient q can be evaluated for a known tapping amplitude. Moreover, we probe the near-field stimulated emission spectrum, which gives the free-space laser light wavelength λ_o and the index of refraction n _r of the laser diode resonant cavity. Once q , λ_o, and n _r are all measured, we can determine the angle of incidence θ_o of the dominant totally internally reflected waves incident on the front mirror facet of the resonator. Determination of such an angle is very important in modelling the stability of the laser diode resonator.     

基于氟化镁晶体微腔产生宽光谱范围克尔光频梳及色散调控研究

为了在基于回音壁模式光学微腔的光学频率梳生成中优化微腔的性能和光频梳的质量,对氟化镁晶体微腔的色散调控进行研究.首先,理论仿真研究了MgF2晶体微腔边缘形状对腔内模场和总色散的影响;接着根据仿真结果实际加工了两种面形的MgF2晶体微腔,分别为边缘平面型和单边楔形;然后,搭建了微腔性能检测系统和晶体微腔光梳生成系统,实测...     

Optimizing the front end test stand high performance H- ion source at RAL

The aim of the front end test stand project is to demonstrate that chopped low energy H(-) beams of high quality can be produced. The beam line currently consists of the ion source, a 3 solenoid low energy beam transport and a suite of diagnostics. A brief status report of the radio frequency quadrupole is given. This paper details the work to optimize the ion source performance. A new high power pulsed discharge power supply with greater reliability has been developed to allow long term, stable operation at 50 Hz with a 60 A, 2.2 ms discharge pulse and up to 100 A at 1.2 ms. The existing extraction power supply has been modified to operate up to 22 kV. Results from optical spectroscopy measurements and their application to source optimization are summarized. Source emittances and beam currents of 60 mA are reported.     

三镜折叠腔绿光激光器热特性分析和实验研究

为了提高固体激光器的热稳定性和光斑质量,讨论了LD泵浦三镜折叠腔绿光激光器的热焦距与泵浦功率、激光晶体长度、泵浦光发散角以及泵浦光聚焦位置的关系.利用谐振腔内往返传输矩阵算法,计算了在不同热焦距下,腔内元件不同长度时,其上的基模半径,理论上很好地实现了输出光斑的像散补偿.在532nm绿光实验中,以Nd∶ YVO4为增益...     

TEACO2非稳腔激光器远场光束质量的评价

研究了对虚共焦非稳腔结构的脉冲TEA CO2激光器远场光束质量进行评价的方法.首先将稳腔TEA CO2激光器加工改造成非稳腔结构;然后从实际设计加工的数据出发,用3种常用形式对其远场光束质量进行理论评价与分析,并与设计的2 kW非稳腔激光器的实测远场光强分布实验结果进行了对比.理论和实验结果表明,非稳腔能够获得接近衍射...     

体布拉格光栅外腔倍频半导体激光器研究

为提高绿光激光器的输出特性,设计了一种体布拉格光栅外腔倍频半导体激光器。采用反射型体布拉格光栅作为反馈元件构成外腔半导体激光器,并使用三硼酸锂晶体进行倍频,研究了基频光的光束及光谱特性对倍频光的光束及光谱特性的影响。实验结果表明,使用体布拉格光栅进行外腔锁波时,所得到的倍频光同样能实现窄带宽输出,同时倍频光的远场分布与基频光的远场分布一致。使用衍射效率为10%的体布拉格光栅作为外腔输出镜,可将半导体激光器的输出波长稳定锁定在1 064 nm,所得到的倍频光波长稳定在532 nm附近,光谱线宽压缩至0.4 nm左右,输出功率可达73 mW。     

耦合式光电振荡器的动态腔长稳定控制

提出了一种基于耦合式光电振荡器的动态腔长长时稳定控制方案,当光谐振腔腔长变化时,通过同相正交（in-phase/quadrature,I/Q）混频器测量光谐振腔内选定两点的谐振相位变化量,反馈控制光电再生腔的光延迟线进行再生腔长跟随补偿,实现可变腔长的耦合式光电振荡器的锁模控制输出,从而将变化的谐振腔腔长转化为变化的谐振频率进行精密测量。经过系统实验,当谐振腔长变化时,振荡器可实时锁定输出可变的微波信号,并保持边模抑制比优于47.26 dB,1 h内功率抖动小于0.28 dB,锁定相位误差抖动在±1.5°以内。     

Scanning Optical Microscopy via a Scanning Electron Microscope

We have described in detail the principles of operation of a commercially available SEM-based scanning optical microscope. The stage consists of a cathodoluminescent material which converts the scanning electron beam into a scanning optical beam and an optical system to focus the light beam onto the specimen. The resolution attainable with such a stage is discussed as well as the efficiency of electron-to-photon conversion. Simplified formulae are given and a set of curves plotted which can be used to determine the appropriate tradeoff between resolution and optical power. Examples of the imaging ability in the optical beam induced current mode from various semiconductor devices are presented.     

三镜直腔结构MgO∶PPLN高效连续光参量振荡器

为了优化MgO:PPLN连续光参量振荡器(OPO)的输出特性,对三镜直腔结构的内腔式OPO系统进行腔结构设计,对其同时输出高效的信号光和闲频光进行研究。采用半导体激光端面抽运Nd:YVO4晶体实现连续的1064 nm激光为基频光。对比分析了基频激光腔和OPO腔各腔镜分别采用平面镜或平凹镜的三种腔型结构的激光输出特性。基于30.5 μm的极化周期和12.4 W入射抽运功率时,获得了最高输出功率3.92 W（信号光2.6 W和闲频光1.32 W）,转化效率31.6%的激光输出,对应的信号光和闲频光的中心波长分别为1549 nm和3394 nm。结果表明三个腔镜均采用平凹镜时,可有效的压缩基频激光腔在MgO:PPLN晶体上的光斑,提升基频激光的功率密度,而且基频激光腔和OPO腔的基模光斑在MgO:PPLN晶体上更好的匹配,从而提升变频效率。     

异质微环谐振腔双稳态及全光存储器应用

提出了一种基于异质集成波导的微环谐振腔,对其双稳态现象进行了研究分析,并将其应用于全光存储功能的实现。异质集成波导具有超高的克尔非线性效应,不受热光效应和载流子响应的限制,在超快克尔非线性效应的支持下,该结构具有快速全光切换的能力。设计了一个高品质因子Q = 77565的微环谐振腔,用耦合模式理论模拟了其双稳态现象。在峰值功率为474 fJ,宽度为20 ps的脉冲激励下,该微环谐振腔很好地实现了全光存储功能,并通过波分复用的串联微环结构展示了波长可寻址的四位光存储器。研究了基于超高克尔非线性效应的双稳态现象,为实现超快切换速度提供了可能性,在光存储、光开关、人工智能研究等方面具有一定的参考价值。     

Roughness measurement with a laser scanning analyser

In the laser scanning analyser a laser beam is reflected from a rotating polygonal mirror so as to scan the workpiece surface at high speed, where it is again reflected into a photodetector which measures the reflected intensity. If the surface is rough, in addition to the specular reflectance the diffuse reflectance due to diffraction is measured as a function of the off-specular angle. In effect the system when used in this mode is a glossmeter which measures the optical properties of a section through the surface and is thus highly suitable for comparison with a stylus instrument. Experiments are described in which reflectance measurements on surfaces finished by various machining processes are compared with stylus roughness measurements. It is found that reflectance measurements are sensitive both to roughness and to the orientation of the lay. Reflectance measurements are found to vary as the average roughness and as the fourth power of the profile slope. There is no correlation with curvature and no evidence of the effect of longer surface wavelengths. There is some evidence that two different scattering mechanisms are involved. Possible applications of such a real-time non-contacting roughness measuring system are described.     

LD泵浦的全固体绿激光器研究

主要论述了用激光二级管(LD)泵浦、内腔倍频的绿激光器的原理和结构。在激光阈值、斜效率的讨论中指出:当LD的泵浦光束在激光晶体中的尺寸越小,光功率密度越高,激光阈值就越低,转换效率就越高;在放大基波的结构中,激光腔镜对基波的反射度越高,基波的放大倍数就越大,转换效率就越高;重点讨论了内腔倍频激光器中的“绿光问题”,指出造成“绿光问题”是由于模式正交分量之间的和频效应与空间烧孔形成的横向饱和;用Poincare图分析了激光器中出现的混沌行为;对如何克服“绿光问题”,得到稳定激光输出提出了几种方案。针对LD的光形状是一个椭圆光锥,选择了用多组透镜准直、棱镜对扩束的泵浦光传输系统方案;对腔体、激光膜层作了概述,具体提出了用平凹腔结构,并把激光膜层直接做在晶体上,可以减少腔内损耗;对YAG-KTP,YVO₄-KTP组合的绿激光器作了研究。在内腔倍频YAG激光器中观察到的实验现象很好地附合理论结果。在YVO₄-KTP的绿激光器中,比内腔倍频YAG激光器较容易得到YAG-KTP组合绿激光器,最大连续输出功率为14.4mW,阈值15.0mW,光-光斜效率为4.1%.YVO₂-KTP绿激光器:最大连续输出120mW,阈值100mW,光-光斜效率为6.3%.     

880nm半导体激光器列阵及光纤耦合模块

为了使半导体激光泵浦Nd∶YVO4固体激光器能获得大功率、高光束质量、线偏振的激光输出,利用PICS3D软件设计了InGaAs/GaAs应变量子阱结构,制作了发射波长为880 nm的大功率半导体激光器列阵。该激光器列阵激射区单元宽为100μm,周期为200μm,填充因子为50%,激光器列阵CS封装模块室温连续输出功率达60.8 W,光谱半高全宽(FWHM)为2.4 nm。为进一步改善大功率半导体激光器列阵的光束质量,增加半导体激光端面泵浦功率密度,采用阶梯反射镜组对880 nm大功率半导体激光器列阵进行了光束整形,利用阶梯镜金属表面反射率受近红外波长变化影响小的特点,研制出高稳定性、大功率光纤耦合模块。模块输出功率为44.9 W,光-光耦合效率达73.8%,尾纤芯径Φ为400μm,数值孔径(NA)为0.22。     

超薄硅衬底氮化铝Lamb波压电谐振器

针对Lamb波压电声波传感器高品质因数(Q值)、低检测极限(LOD)和易集成的性能要求,本文基于SOI(Siliconon-insulator)硅片,通过底层硅(Handling layer)干法刻蚀和中间层(Boxing layer)自截止的方法实现2μm超薄均一的硅衬底结构,然后沉积2μm厚具备高C轴择优取向的氮化铝(AlN)压电薄膜。传感器薄膜区域外设置双端增强反射栅结构用于提高Q值,从而有效降低器件的检测极限,并通过微量水分测试验证性能。该谐振器零阶反对称模式(A0)和零阶对称模式(S0)的谐振状态的实测结果和COMSOL二维模型仿真结果一致,所制作的Lamb波谐振器A0模式的主峰Q值为703,S0模式的主峰Q值为403。微量水分测试S0模式的检测极限优于A0模式,最低检测极限值为0.06%RH。结果表明,氮化铝超薄硅衬底Lamb波压电谐振器能够实现微量水分等高精度检测。