X射线荧光光谱分析样品烧增量的影响及校正

研究采用熔融法制备矿石样品时出现的烧增量问题,建立新的校正方法.硫化物矿的烧增量有百分之几十,它改变基体组成,造成基体校正的错误,新方法先将具有烧增量的样品转换成具有烧失量的新样品,然后用差减法校正烧失量,用理论影响系数法校正基体效应,求得新样品的结果,最后再换算回原样的结果.此方法以铜精矿为实验对象,比较差减法和重量...     

超二代及三代像增强器不同响应波段的参数测量及比较

对A光源分别进行550 nm、625 nm以及675 nm的短波截止,对比测量了超二代和三代像增强器的光谱响应、阴极灵敏度、增益、分辨力以及信噪比。在10^-1lx照度条件下,当对A光源进行675 nm的短波截止之后,三代像增强器的分辨力未出现下降,而超二代像增强器的分辨力却下降到初始值的94%;但在10^-4lx照度条件下,当对A光源进行675 nm的短波截止之后,三代像增强器的分辨力下降到初始值的90%,而超二代像增强器的分辨力下降到初始值的85%。但信噪比越高的像增强器,分辨力降低的比例越低。对于超二代和三代像增强器而言,如果在A光源条件下的性能参数相同,但在不同的短波截止条件下使用时,其性能并不相同,三代像增强器的性能更好。尽管超二代像增强器在不同短波截止波长条件下性能参数下降的比例较三代像增强器下降的比例高,但差距并不大,因此使用过程中的性能差距也不大。     

Suppression of Output Power and NF Excursions in Cascades of Highly Inverted EDFAs with Packet-Switched Traffic

Significant output power excursions in cascades of erbium-doped fiber amplifiers (EDFAs) can cause serious problems in wavelength division multilexing (WDM) packet-switched burst-mode networks. Signal power excursions more serious than those induced by channel addition/removal in circuit switched networks can arise when data on the WDM channels is highly variable in nature. Self-similar traffic can be subject to large variation in EDFA gain. In order to prevent unacceptable error bursts, due, for example, to channel power becoming too low to preserve adequate eye opening or exceeding thresholds for optical nonlinearities, the channel power should be maintained constant. In this letter, it is shown that the sizable power and noise figure swings arising in a cascade of EDFAs with WDM burst-mode packet-switched networks with self-similar traffic can be effectively suppressed when highly inverted amplifiers are employed. The analysis is based on the application of a numerical model, which solves the transcendental equation for length averaged metastable level population of an EDFA.     

Gain Controlling of Erbium-Doped Fiber Amplifier by Samarium Doped Inner-Cladding in the 1.5µm Region

In this work, WDM transmission with 40-Gbit/s per channel bit rate has been experimentally demonstrated over a 500-km link. Different chromatic dispersion conditions have been managed and in-line all-optical wavelength conversion has been carried out with a periodical poled lithium niobate (PPLN) device in a polarization-independent scheme. The link was obtained by connecting the fibers contained in an installed cable between Roma and Pomezia (25 km), encompassing single-mode (G.652) and high-end (G.655, non-zero dispersion with a particular value and flat curve for chromatic dispersion) fibers. Some 40 Gb/s channels were propagated in the link 500 km long and one channel was dropped from the link after 300-km propagation, wavelength converted, and added to the other channels for the next 200 km. The electrical data interfaces exploited a 4 × 10 Gbit/s to 1 × 40 Gbit/s MUX at the transmitter, along with a 1 × 40 Gbit/s to 4 × 10 Gbit/s DMUX at the receiver. Successful transmission of 4 channels, 200-GHz spaced, has been achieved over 500 km along both G.652 and G.655 links. No evidence of penalty comparing converted and unconverted channels has been reported. Transmission experiments of 8 × 40 Gbit/s, with 100 GHz frequency spacing, are also reported. No significant degradation has been observed in the case of the G.652 link.     

线性啁啾光脉冲在具有纵向增益光纤中的自相似传播研究

非线性薛定谔方程是光脉冲在光纤中传播时所遵循的基本方程.本文利用分步傅里叶方法从数值结算的角度研究了具有线性啁啾的光脉冲在具有横向增益光纤中的自相似传播特性.研究表明:当群速度色散系数和光脉冲的啁啾系数符号相同时,由于在传播过程中自相位调制和群速度色散分别起主要作用,不论何种形式的光脉冲在传输过程中均会受到压缩,但随着传播距离的增加压缩的光脉冲会展宽;埃尔米特高斯输入和正弦输入在传播过程中的光强分布是对称的,拉盖尔高斯输入在传播过程中会发生能量交换而表现出明显的偏转;当群速度色散系数和光脉冲的啁啾系数符号不相同时,在传播过程中群速度色散始终起主要作用,脉冲一直展宽.这些研究结论可能为未来光纤压缩器、光纤放大器以及新型THz调制波源的制备提供新的理论基础和方法.     

Gain and gain-flatness improved photonic crystal fiber Raman amplifier based on a dual-pass amplification configuration with single pump laser

A gain and gain-flatness improved L-band dual-pass Raman fiber amplifier (RFA) utilizing a photonic crystal fiber (PCF) as gain medium is demonstrated. By introducing complementary gain spectra of typical forward and backward pumping single-pass RFA using the same PCF, we finally achieve average net gain level of 22.5 dB with a ±0.8 dB flattening gain in 20-nm bandwidth from 1595 nm to 1615 nm, which is rare in RFAs with only one single pump and no flattening filter. Compared with the single-pass pump configurations, gain level, flatness and bandwidth are greatly improved by using the dual-pass amplification configuration. The limitation of this configuration caused by multi-path interference (MPI) noise and stimulated Brillouin scattering (SBS) is also discussed.     

Design of dual-core resonant leaky optical fibre based gain flattening filters for erbium doped fibre amplifiers

We propose optical fibre based filters employing dual-core resonant leaky structure for gain equalization of erbium doped fibre amplifier (EDFA). Spectral loss variation of the structure has been utilized to suppress gain peak and, thus, flatten overall gain profile in the C-band. We show 15.7 dB flat gain with ± 1.6 dB ripple in the wavelength range from 1525 nm to 1555 nm using a single filter and 18±0.7 dB gain using two cascaded filters.     

Solving traveling-wave rate equations of semiconductor lasers including gain compression factor

An implicit analytical solution for the geometric mean of the photon density of the counter-propagating fields inside the diode laser (LD) cavity has been derived from the steady-state traveling-wave rate equations including the gain suppression factor. Together with the expression of the position-dependent photon density and carrier density in terms of the geometric mean, the implicit analytical solution for the rate equations has been obtained. With the aid of the solutions, the effects of the gain suppression on static characteristics of LDs have been quantified.     

基于腔衰荡技术的光纤双环路一氧化碳浓度监测系统研究

对光纤环形腔技术的传感原理进行了理论推导,并设计了一种双环路一氧化碳浓度测量系统.分析了掺铒光纤放大器在系统中的作用及其增益波动对系统的影响,通过对掺铒光纤放大器的增益进行反馈控制,进一步了提高了测量系统的稳定性和精确性.通过实验,得出了不同浓度的一氧化碳所对应的衰荡曲线.分析了不同浓度的气体对光的吸收特性及衰荡时间与浓度的关系,为实现气体浓度的高准确度在线测量提供了重要的依据.     

电子倍增CCD倍增要件研究

讨论了信号栽流子倍增寄存器(CCM)结构及其工作原理,在此基础上建立了电子倍增CCD的碰撞电离模型.通过对CCM倍增结构的研究发现实现倍增的三个必要条件:适中的倍增级电场、适当的浅掺杂浓度以及与电子碰撞平均自由程相当的倍增距离.通过建模研究均匀场强中增益情况表明增益因子为0.01时对应的偏置电压接近EMCCD所用倍增电压.