脊形掺铒Al2O3光波导放大器级联特性的模拟计算

利用有限元法分析了脊形掺铒Al₂O₃光波导放大器内信号光和抽运光的场模式分布、速率方程求解铒离子五能级系统的粒子数分布.数值模拟了光波导净增益与信号光功率的关系和多个放大器级联的净增益特性.结果表明：级联系统存在着净增益亏损.低掺铒浓度的光波导作前级放大器的组合方式,级联系统总净增益最大.     

硅波导受激喇曼散射放大信号光的数值模拟

提出了用连续泵浦光在硅波导中的受激喇曼散射对信号光进行放大的方法.建立了信号光和泵浦光在硅波导中传输的耦合方程,得到了计算信号光增益的理论模型.利用数值模拟结果,对泵浦功率沿波导的分布,信号光在不同波导长度以及输入功率情况下的增益等进行了分析和讨论.结果表明,适当增加波导长度和泵浦光功率可以得到较高喇曼增益的结论.     

掺铒铌酸锂波导放大器增益特性的理论分析

对掺铒铌酸锂（Ｅｒ３＋：ＬｉＮｂＯ３）波导放大器在１４８０ｎｍ泵浦光单向和双向泵浦下的增益特性作了计算机模拟理论分析,采用二能级速率方程,忽略ＥＳＡ的影响,应用数值法得出方程解,优化设计放大器参数     

Ultrawide-bandwidth gain in a coaxial dielectric Cherenkov maser

A coaxial waveguide partially filled with a dielectric as the slow-wave structure of a dielectric Cherenkov maser is investigated. The dispersion of the fundamental mode of this waveguide is very weak at phase velocities close to the velocity of light, and for this reason a very wide gain bandwidth is possible under conditions of an interaction with a relativistic electron beam. The dispersion equation for an infinitely thin tubular beam in a coaxial waveguide with a dielectric liner adjoining either the outer or inner conducting surface is derived. The gain bandwidth as a function of the parameters of the electron beam and the slow-wave system are investigated on the basis of numerical solution of the dispersion equation, and a comparison with similar dependences for the conventional configuration of a dielectric Cherenkov maser is made. The structural features of the coaxial configuration which enable novel approaches to the problems of matching the microwave signal at the entrance and exit of the system are discussed. Zh. Tekh. Fiz. 67, 66–72 (May 1997)     

掺铒玻璃波导放大器中抽运光信号光重叠因子分析

通过分析掺铒(Er3 )玻璃波导放大器(EDWA)的放大增益机理,提出抽运光与信号光光模场分布之间的归一化重叠积分因子(Γ),并引入到掺铒波导放大器增益模拟计算中,使理论模型更切合实际。以Ag -Na 二次离子交换工艺制作的具有埋入型渐变折射率分布的掺铒波导放大器为例,采用数值方法模拟了条形波导截面上的二维折射率分布及抽运光、信号光的光模场分布。计算了不同工艺参量设置下的Γ大小,讨论Γ对放大器增益的影响。结果显示,在二次离子交换制作过程中设置适当工艺参量优化折射率分布,能有效改善波导中抽运光与信号光光模场分布之间的重叠因子,提高掺铒波导放大器的增益。计算结果显示,在一定条件下,Γ从0.5增至0.8,每厘米长度掺铒波导放大器的放大增益可提高近1.5 dB。     

A Ku-BAND WAVEGUIDE FREQUENCY MULTIPLIER USING HARMONIC-REJECTION MICROSTRIP PATCH TRANSITIONS

A compact frequency multiplier waveguide module is built by placing a planar microstrip section between two rectangular waveguides. The size of the microstrip section is minimized by eliminating all harmonic band-rejection filters. Special feed locations for the input waveguide-to-microstrip transition patches provide the second-harmonic rejection at the input, and a balanced circuit configuration formed with a pair of transistors produces the pump signal cancellation at the output. The measurements on a fully-assembled waveguide module showed a peak frequency conversion gain of-2.3 dB at 16.7 GHz with the associated output power level of 6 dBm.     

Nonlinear Phase Shift by Parametric Amplification in Leaky Waveguides

In this article, the cascaded second-order nonlinear phase shifts induced in the signal wave are studied using the three-wave parametric interaction in a four-layered QPM leaky waveguide configuration in Z-cut LiNbO 3 . In this interaction, the pump-andsignal waves are guided modes and the idler is radiated into the substrate. We have analyzed the nonlinear phase shifts induced in the signal wave due to cascaded second-order effects, as a function of different waveguide parameters. These studies should find application in realizing practical all-optical signal processing devices.     

Nonlinear Phase Shift by Parametric Amplification in Leaky Waveguides

In this article, the cascaded second-order nonlinear phase shifts induced in the signal wave are studied using the three-wave parametric interaction in a four-layered QPM leaky waveguide configuration in Z-cut LiNbO 3 . In this interaction, the pump-andsignal waves are guided modes and the idler is radiated into the substrate. We have analyzed the nonlinear phase shifts induced in the signal wave due to cascaded second-order effects, as a function of different waveguide parameters. These studies should find application in realizing practical all-optical signal processing devices.     

Performance analysis of dual-pump optical parametric amplifiers in silicon waveguide

Nondegenerate Four Wave Mixing (FWM) process in a silicon waveguide is influenced by two photon absorption (TPA), TPA induced free carrier absorption (FCA) besides self-phase modulation (SPM), cross-phase modulation (XPM), SRS, GVD and linear scattering losses. Influences of pump parameters of the dual-pump parametric amplifier (OPA) in the silicon waveguide on gain spectrum and noise figure are numerically investigated. Compared with single-pump configuration, dual-pump silicon OPA indicates a flat gain and noise figure. Then impact of waveguide dispersion on bandwidth and ripples for dual-pump silicon optical parametric amplifiers is discussed. Optimal pump configurations are evaluated. The results show that polarization independent net gain of silicon OPA can be achieved by using circular and orthogonally polarized pump.     

抽运光与信号光的光强重叠因子和掺铒玻璃波导放大器的增益特性

在掺铒玻璃波导放大器（EDWA）的三能级速率-传输方程中,考虑两次离子交换工艺中波导掩模窗口宽度w不同所导致的抽运光、信号光模场与光强分布的不同,讨论不同w对EDWA增益特性的影响,得到光强分布的数值解.引入描述波导中抽运光和信号光的归一化光强重叠因子,对EDWA的传统近似解提出修正,得到了修正解,使其更加接近光强分布的数值解.模拟结果表明,在条波导长度为4 cm、抽运光波长为980 nm、功率为80 mW、信号光波长为1534 nm、功率为-10 dBm条件下,不同w所导致EDWA的增益差别可达297 dB.修正解的结果比传统近似解更加接近光强分布的数值解.修正解对于EDWA的理论研究、器件设计具有指导作用. 关键词： 集成光学 掺铒玻璃波导放大器 重叠积分因子 增益     

Mode-selective amplification in a waveguide free electron laserwith a two-sectioned wiggler

One important issue in waveguide free electron lasers (FELs) involves an interaction of the electron beam with one waveguide mode at two different resonant frequencies. Since the low-frequency mode often has a higher pain, the usually preferred high-frequency mode is suppressed as a result of mode competition. In this paper, possible control of this mode competition is considered using a nonstandard wiggler magnet consisting of two cascaded wiggler sections with different periods and field strengths. It is demonstrated that with an appropriate differentiation between the two wiggler sections the high-frequency mode may be amplified preferentially. This mode-selective amplification may be used to suppress the low-frequency mode. A small signal gain formulation is developed for a waveguide FEL with such a two-sectioned wiggler arrangement and numerical examples are used to demonstrate its applicability to mode control in waveguide FELs. Effects of wiggler field errors and electron energy spread are also considered. It is shown that the requirement for wiggler field errors and electron energy spread in the two-sectioned wiggler arrangement is similar to that in the usual straight wiggler configuration     

结构参数对折叠波导行波管工作性能的影响

分析和计算了互作用区折叠波导截面长宽比(b/a)、直边高度和电子束通道大小等结构参数对太赫兹波段折叠波导行波管工作性能的影响。结果表明：互作用区衰减常数随b/a的增大而减小, 耦合阻抗和小信号增益则随b/a的增大先增加而后减小, 存在最优值。电子束通道越大, 衰减常数越大, 耦合阻抗和小信号增益降低得越多。相对于电子束通道, 增益和损耗对直边高度的敏感程度显著降低。因此为了提高器件功率容量, 可适当增加折叠波导的高度;在保证电子束能够顺利传输的前提下, 电子束通道越小越好。在折叠波导行波管的实际研制中, 可依据具体的实验条件和要求, 在适当的范围内合理选取互作用区各结构参数的值。     

结构参数对折叠波导行波管工作性能的影响

分析和计算了互作用区折叠波导截面长宽比(b/a)、直边高度和电子束通道大小等结构参数对太赫兹波段折叠波导行波管工作性能的影响。结果表明:互作用区衰减常数随b/a的增大而减小, 耦合阻抗和小信号增益则随b/a的增大先增加而后减小, 存在最优值。电子束通道越大, 衰减常数越大, 耦合阻抗和小信号增益降低得越多。相对于电子束通道, 增益和损耗对直边高度的敏感程度显著降低。因此为了提高器件功率容量, 可适当增加折叠波导的高度;在保证电子束能够顺利传输的前提下, 电子束通道越小越好。在折叠波导行波管的实际研制中, 可依据具体的实验条件和要求, 在适当的范围内合理选取互作用区各结构参数的值。     

Yb3+sensitized Er3+-doped waveguide amplifiers: a theoretical approach

Silicate and phosphate glass waveguide amplifiers doped with Er³⁺, and co-doped with Er³⁺/Yb³⁺ are theoretically studied. Configurations for core and core–cladding doped waveguide amplifiers are considered. It is shown that gain in the core–cladding doped amplifiers is considerably higher than core doped amplifiers. It is also shown that with input signal power up to 1 and 200mW pump power, a 12.5dB gain can be achieved in a 3cm long waveguide amplifier, with a noise figure of 3dB.     

Kα波段介质加载回旋行波管小信号分析与设计

应用分析回旋行波管绝对不稳定性的Briggs-Bers相碰判据与小信号色散方程,并结合介质加载波导的冷场分析,通过数值计算比较了不同介质加载条件下回旋行波管工作模式的起振电流与寄生模式的起振长度,通过改变加载介质的特性参数从而增加行波损耗可以显著提高工作模式起振电流,并抑制掉寄生模式的返波振荡.结合介质加载波导冷场分析与回旋行波管小信号色散方程,分析了介质加载条件下回旋行波管小信号增益,给出了不同介质加载条件下的回旋行波管的小信号增益带宽曲线.在对介质回旋行波管自激振荡与小信号增益的综合分析基础上,对Kα 关键词： Kα波段介质加载回旋行波管 绝对不稳定性 自激振荡 小信号增益     

Linear Analysis of Folded Double-Ridged Waveguide

A novel slow-wave structure (SWS), the folded double-ridged waveguide structure, is presented and its linear gain properties are investigated. The perturbed dispersion equation is derived and the small signal growth rate is calculated for dimensions of the ridge-loaded region and the parameters of the electron beam. The novel structure has potential applications in the production of high power and broad band radiation. For a cold beam, the linear theory predicts a gain of 1.1-1.27dB/period and a 3-dB small-signal gain bandwidth of 30% in W-band. A comparison between the folded double-ridged waveguide SWS and folded waveguide SWS (FWSWS) shows that with the same physical parameters, the novel SWS has an advantage over the FWSWS on the bandwidth and electron efficiency.     

Influence of multimode-pump propagation on the gain characteristics of erbium–ytterbium doped waveguide amplifier

Channel waveguides with channel opening widths (COWs) from 4.5 to 7.5 μm with increment of 0.5 μm have been fabricated by two-step ion exchange on the same erbium-ytterbium uniformly doped phosphate glass substrate of 4.3-cm length. Experimental results indicate that the gain for 1534-nm small signal light pumped at saturation is maximized and shows a 3.6-dB enhancement for these erbium-ytterbium doped waveguide amplifiers (EYDWAs). The intensity profile overlap between signal and multimode-pump light in waveguide leads to the improvement in the gain of EYDWA. This can be used to explain the experimental results and shows the general dependence of the gain characteristics on the modal behavior of EYDWA. The presence of higher order modes of pump light and the optimization of this intensity profile overlap are significant to improve the gain properties of EYDWA.     

Effect of betatron oscillations on waveguide free electron laser gain

In this paper we analyse the spontaneous emission and gain spectrum of a waveguide free electron laser with betatron motion included in the analysis. The zero slippage condition and the small signal gain in the waveguide free electron laser is discussed.     

Estimation of efficiency of vertical antenna arrays in underwater sound channels

The gain of the vertical antenna array in a randomly inhomogeneous ocean waveguide is numerically simulated on the assumption that the useful signal is generated by a finite set of mutually uncorrelated discrete spectrum modes and is received against the ocean noise background. It is shown that the choice of themost effective weight distribution of the array and the thus obtained gain strongly depend on both the modal spectra of the signal and noise and the number and position of the receiving elements in the channel. The critical factor is the mutual orthogonality of the waveguide modes at the array input, which indicates the possibility of specially arranging the elements for the known (expected) mode spectrum of the signal.     

掺铒聚合物光波导放大器的数值分析

针对掺铒聚合物光波导放大器(EDWA),提出了一种基于Douglas离散格式改进的有限差光束传播法(FD-BPM)的数值计算方法。对每一传输步长结合多能级速率方程计算出EDWA中光场传输强度分布,及掺铒光波导放大器的增益传输特性。设计并研究了掺铒聚合物通道波导和Y形分束器的放大增益特性。在掺铒聚合物直波导中,Er3 浓度为9.0×1025ions·m-3,输入信号和泵浦光功率分别为1μW和2mW,其增益为1.6dB/cm;在掺铒聚合物Y形分束器中,输出信号光分束比相等,并能实现无损耗分束。