应用空心阴极灯激光激发的荧光法研究高激发态镍原子的高分辨光谱

根据具有两条跃迁上能级间隔距离很大而波长差很小的原子谱线的元素在吸收满足共振跃迁的特定波长激光后可能产生波长差很大的非共振荧光线的特点,我们应用空心阴极灯激光激发荧光法,通过探测分别属于z~3D_3~0→f~3D_2和z~1D_2~0→f~1D_2跃迁的5142.77891A和5176.56337A荧光线的轮廓和线宽,间接把上述两条高分辨谱线分辨开。     

钡蒸汽中串级碰撞诱导受激辐射

观测并标识了钡蒸汽中源于受激喇曼终态的若干串级碰撞诱导受激辐射线:354.50nm(6s5f~3F_3~0—6s5d~3D_2)、394.40nm(6s8d~3D_2—6s6p~3P_1~0)、410.0nm(6s8d~3D_16s6p~3P_2~0)及973.50nm(5d7p~1P_1~0—6s7s~1S_0)。 为获得新的频率转换,许多作者对金属蒸汽中的光学非线性效应作了广泛的研究。本     

SrBa(SO_4)_2∶Sm~(2+)的光谱及光子选通光谱烧孔效应

报道了Sm~(2+)在SrBa(SO_4)_2混晶中的光谱性质和光子选通光谱烧孔效应。在这个材料中Sm~(2+)的~5D_o-~F_o歹。跃迁的不均匀增宽达1nm(766GHz)。利用Ar~+激光在514.5nm的输出和可调谐连续染料激光器在625.8nm附近的输出,在5K观测到~5D_1←→~7F_o跃迁的光子选通光谱烧孔效应。同时给出了Sm~(2+)在SrBa(SO_4)_2中的电子能级和有关的荧光和激发光谱。     

双光子激发钡原子蒸汽中原子发射的实验研究

在工作用波长为528.5nm、534.2nm及539.2nm染料激光脉冲,对钡蒸汽原子基态进行选择激发,分别使5d6d~1D_2、6s7d~1D_2及5d6d~3F_2态获得布居,产生由双光子共振吸收引起的一系列红外及可见原子辐射线。     

高Q微波介质陶瓷材料D_3的研制

本文介绍了高Q微波介质陶瓷材料D_3的研制结果。较详细地叙述了该材料样品制备过程中各种工艺的选择及控制方法。并列出用这种工艺制备的微波介质陶瓷材料D_3的微波性能和测试方法。通过本文列举的利用D_3材料制成的10.5GHz介质谐振器滤波器和8.2GHz介质谐振器振荡器的性能指标,说明该材料在X波段、K波段制作介质谐振器振荡器、介质谐振器滤波器等方面将被广泛地采用。     

脉冲光泵CH_3F和D_2O远红外喇曼激光器

用宽脉冲(3μs)高能密度(3～12J/cm~2)的TEA-CO_2激光辐射,作高达35GHz的偏离共振的脉冲光泵浦,已激励了稳定光腔远红外激光器中的CH_3F和D_2O介质,有效地获得了22条CH_3F的和9条D_2O的高强度远红外喇曼激光辐射,其中CH_3F的447.7μm以及D_2O的96.47μm和130μm等3条谱线为国内外首次报道。     

U原子能级

本文用MCDF方法对U原子5f~36d7s~2、5f~36d~27s、5f~36d7s7p、5f~26d~27s~2、5f~47s~2、5f~37s~27p和5f~46d7s组态的能级进行了计算,发现U原子一些偶宇称能级的组态标定是不正确的.     

高性能宽频带碲镉汞探测器

本文研究77°K工作的8～14微米碲镉汞探测器的响应率与探测器噪声的频率关系。结果表明,这些参数具有同样的频率关系与拐角频率。对D_λ~*～5×10~(10)厘米~(1/2)瓦~(-1)的探测器,实验得出f~*值≥10兆赫。同时看出,结果与假定空穴和电子寿命相等的简单光电导理论一致。     

半导体DFB激光多波长锁定器

密集波分复用(DWDM)技术是扩大光纤通信传输容量的有效途径,国际通信联盟(ITU)规定了光纤中光载波信道间距为100GHz或50GHz,相应的波长间距分别为0.8 nm和0.4 nm,这便要求各信道上的DFB激光器的波长有较高的稳定度,例如波长漂移<2 GHz。     

无线通信失真补偿技术得到应用适用于3G手机的收发器

在UWB领域,飞利浦公司发布的UWB收发器符合WiMedia标准,支持#1(3GHz～5GHz)和#3(6～8GHz)两个频段.利用65nm CMOS工艺实现的RF单元,尺寸仅为以前的1/2左右[6.1].     

Laterally scaled Si-Si/sub 0.7/Ge/sub 0.3/ n-MODFETs with f/sub max/>200 GHz and low operating bias

We report on the dc and RF characterization of laterally scaled, Si-SiGe n-MODFETs. Devices with gate length, L/sub g/, of 80 nm had f/sub T/=79 GHz and f/sub max/=212 GHz, while devices with L/sub g/=70 nm had f/sub T/ as high as 92 GHz. The MODFETs displayed enhanced f/sub T/ at reduced drain-to-source voltage, V/sub ds/, compared to Si MOSFETs with similar f/sub T/ at high V/sub ds/.     

A D‐Band Balanced Subharmonically‐Pumped Resistive Mixer Based on 100‐nm mHEMT Technology

A D‐band subharmonically‐pumped resistive mixer has been designed, processed, and experimentally tested. The circuit is based on a 180° power divider structure consisting of a Lange coupler followed by a λ/4 transmission line (at local oscillator (LO) frequency). This monolithic microwave integrated circuit (MMIC) has been realized in coplanar waveguide technology by using an InAlAs/InGaAs‐based metamorphic high electron mobility transistor process with 100‐nm gate length. The MMIC achieves a measured conversion loss between 12.5 dB and 16 dB in the radio frequency bandwidth from 120 GHz to 150 GHz with 4‐dBm LO drive and an intermediate frequency of 100 MHz. The input 1‐dB compression point and IIP3 were simulated to be 2 dBm and 13 dBm, respectively.     

10-GHz power performance of a type II InP/GaAsSb DHBT

Type-II InP/GaAsSb double heterojunction bipolar transistors (DHBTs) were fabricated and microwave power performance was measured. For an InP collector thickness of 150 nm, the DHBTs show a current gain of 24, low offset voltages, and a BV/sub CEO/>6V. The 1.2/spl times/16 /spl mu/m/sup 2/ devices show f/sub T/=205GHz and f/sub MAX/=106GHz at J/sub C/=304 kA/cm/sup 2/. These devices delivered 12.6 dBm to the load at P/sub AVS/=3.3 dBm operating at 10 GHz, yielding a power-added efficiency of 41% and G/sub T/=9.3 dB.     

Wideband DHBTs using a graded carbon-doped InGaAs base

We report an InP/InGaAs/InP double heterojunction bipolar transistor (DHBT), fabricated using a mesa structure, exhibiting 282 GHz f/sub /spl tau// and 400 GHz f/sub max/. The DHBT employs a 30 nm InGaAs base with carbon doping graded from 8/spl middot/10/sup 19//cm/sup 3/ to 5/spl middot/10/sup 19//cm/sup 3/, an InP collector, and an InGaAs/InAlAs base-collector superlattice grade, with a total 217 nm collector depletion layer thickness. The low base sheet (580 /spl Omega/) and contact (<10 /spl Omega/-/spl mu/m/sup 2/) resistivities are in part responsible for the high f/sub max/ observed.     

Simultaneous all-optical frequency downconversion technique utilizing an SOA-MZI for WDM radio over fiber (RoF) applications

Simultaneous all-optical frequency-downconversion technique utilizing a semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) is experimentally demonstrated, and its application to a wavelength-division-multiplexing (WDM) radio over fiber (RoF) uplink is proposed. The conversion efficiencies from 22.5 (f/sub RF/) to 2.5 GHz (f/sub IF/=f/sub RF/-2f/sub LO/) are in the range from 1.5 to 3 dB for the optical RF wavelength between 1548 and 1558 nm. Error-free simultaneous all-optical frequency downconversion of the two WDM RoF upstream channels that carry 155-Mb/s differential phase-shift keying data at 22.5 GHz to an optical intermediate frequency signal having the frequency of 2.5 GHz with the power penalty less than 0.1 dB at the bit error rate of 10/sup -8/ is achieved.     

Integrated-optical gigahertz frequency shifter for 1.5 μmsignals

A single-sideband modulator for gigahertz modulation frequencies is demonstrated in Ti:LiNbO₃. At a frequency shift of Δf 5.9 GHz, the optical bandwidth is δλ=20 nm and the electrical bandwidth δf=0.25-1 GHz     

50/100GHz AWG型光学梳状滤波器的设计与制备

以Si基SiO2平面光波导为基础,设计并制备了50/100GHz AWG型光学梳状滤波器．制备得到的AWG型光学梳状滤波器可以覆盖1520～1585nm的波长范围,共有160个信道．功率输出不均匀度＜0.5dB,插入损耗＜8dB,相邻通道的串扰＞13dB,在距离中心频率最远的信道,输出频率偏离ITU标准15GHz．分析了影响器件串扰和信道频率偏移的原因,并提出了相应的解决办法．     

基于非线性色散补偿光栅的可调谐光电振荡器

为实现光电振荡器(OEO)输出频率的连续可调,提出一种新型的基于非线性色散补偿光栅(FBG)实现可调谐OEO方案。本文方案不需要电滤波器,且振荡频率随着光源的波长变化而变化。其中,三阶色散补偿FBG可以采用FBG重构算法设计。当光源波长从1 550.6nm变化到1 551.4nm时,相应的色散为340～1 460ps/nm,输出频率的调谐范围为6.5～13.5GHz,实现了振荡频率的大范围可调谐。     

一种基于SiGe BiCMOS的高速采样/保持电路

设计了一种基于BiCMOS工艺的高速采样/保持电路,该工艺提供了180 nm的CMOS和75 GHz fT的SiGe HBT.差分交换式射极跟随器和低下垂输出缓冲器的结合,使电路具有更好的性能.在Cadence Spectre环境下进行仿真,当输入信号为968.75 MHz、Vpp为1 V的正弦波,采样速率为2 GSPS时,该采样/保持电路的SFDR达到62.2 dB,THD达到-59.5 dB,分辨率达到9位;在3.3 V电源电压下,电路功耗为20 mW.     

AlGaN/GaN high electron mobility transistors with InGaN back-barriers

A GaN/ultrathin InGaN/GaN heterojunction has been used to provide a back-barrier to the electrons in an AlGaN/GaN high-electron mobility transistor (HEMT). The polarization-induced electric fields in the InGaN layer raise the conduction band in the GaN buffer with respect to the GaN channel, increasing the confinement of the two-dimensional electron gas under high electric field conditions. The enhanced confinement is especially useful in deep-submicrometer devices where an important improvement in the pinchoff and 50% increase in the output resistance have been observed. These devices also showed excellent high-frequency performance, with a current gain cut-off frequency (f/sub T/) of 153 GHz and power gain cut-off frequency (f/sub max/) of 198 GHz for a gate length of 100 nm. At a different bias, a record f/sub max/ of 230 GHz was obtained.