低温生长AlGaAs／GaAs多量子阱中的超快过程研究

半导体材料无论在应用领域，还是在基础研究中都有重要的意义，对其中超快过程的研究近年来已成为研究的热点之一．低温生长的AlGaAs／GaAs多量子阱材料具有超短的非平衡载流子复合寿命，广泛应用于超快光学元件中．我们利用飞秒激光泵浦一探测技术对其中的超快过程进行了研究。     

土壤反硝化培养气体中N_2和O_2的气相色谱测定方法

为测定土壤反硝化培养气体中的N_2和O_2的浓度,利用厌氧箱制备样品,建立了自动进样器阀进样、填充柱分离,气相色谱-热导检测器测定的方法。N_2和O_2在2min内达到基线分离。对于低浓度的样品(N2≤1.0%,O2≤0.254%),使用厌氧箱后N_2和O_2测定的峰面积比未使用时相比降低约20.0%。目标分析物的保留时间和峰面积的相对标准偏差(RSD)分别小于0.1%和1.0%。N_2和O_2的线性范围分别为780~60 100μmol/mol和290~20 000μmol/mol,线性相关系数均在0.999以上,检出限分别为232.7μmol/mol和87.5μmol/mol。厌氧箱的使用很大程度上避免了空气中的N_2和O_2进入,使培养气体中低含量N_2和O_2的测定更加准确。     

低温生长垂直场多量子阱光折变器件的工作特性研究

本文对低温生长的垂直场ＭＱＷｓ光折变器件电吸收瞬态特性进行了研究,在分析垂直场ＭＱＷｓ器件结构后,我们认为电光层并不单独由多量子阱层构成,而是包括多量子阱层和两边低温生长的缓冲层构成,为此,我们提出了改进的阻容模型,并用这一模型很好地解释ＴＭＱＷｓ光折变器件电吸收瞬态特性的实验结果,同时对ＭＱＷｓ器件性能的提高提出了建议．本文还对垂直场ＭＱＷｓ光折变器件的读光、写光与衍射效率关系进行了研究,给出了垂直场ＭＱＷｓ器件工作的最佳光强条件,并对实验现象进行了解释,指出了由于同样是读光、写光增强导致器件…     

Influence of optical nonlinearity on combining efficiency in ultrashort pulse fiber laser coherent combining system

The influence of optical nonlinearity on combining efficiency in ultrashort pulse fiber laser coherent combining system is investigated theoretically and experimentally. In the theoretical work, a new theoretical algorithm is presented for the coherent combining efficiency, which can be used to quantify the spectral coherence decay induced by optical nonlinearity imbalance between the sub-beams. The spectral information of the sub-beam is obtained by numerically solving the nonlinear Schrödinger equation (NLSE) in this algorithm to ensure an accurate prediction. In the experimental work, the coherent combining of two all-fiber picosecond lasers is achieved, and the influence of imbalanced optical nonlinearity on the combining efficiency is studied, which agrees with the theoretical prediction. This paper reveals the physical mechanism for the influence of optical nonlinearity on the combining efficiency, which is valuable for the coherent combining of ultrashort pulse fiber laser beams.     

STUDY OF THE FOUR-WAVE MIXING DIFFRACTION EFFICIENCY OF LONGITUDINAL-FIELD MULTIPLE-QUANTUM-WELL PHOTOREFRACTIVE DEVICE GROWN AT LOW TEMPERATURE

We investigate the relationship between the beam intensity and the four-wave mixing diffraction efficiency of longitudinal-field multiple-quantum-well(LMQW) photorefractive device grown at low temperature. The optimum beam intensity is found. We also explain the different mechanisms of the effect of beam intensity on the diffraction efficiency of the LMQW device and the transverse-field MQW device. Some advice on how to improve the diffraction efficiency is given.     

Oscillation conditions of cw simultaneous dual-wavelength Nd：YAG laser for transitions 4F3／2-4I9／2 and 4F3／2-4I11／2

The operating condition of a cw simultaneous dual-wavelength Nd:YAG laser for both {}^4F_{3/2}-{}^4I_{9/2} (quasi-three-level system) and {}^4F_{3/2}-{}^4I_{11/2}(four-level system) transitions is studied. According to this condition, the cw simultaneous dual-wavelength at 1.06μm and 946 nm in Nd:YAG crystal has been realized experimentally through an adaptive coating design of the cavity mirrors. A total power output of 2.5W of the dual-wavelength at 946nm and 1.06μm has been achieved with an optical conversion efficiency 14.3%. The experimental results are in good agreement with the theoretical analysis.     

Nd,Cr:YAG自调Q自锁模激光器的研究

实验采用光纤耦合激光二极管泵浦,得到了二极管泵浦Nd,CrYAG自调Q自锁模1.064 μm激光输出,其锁模调制深度达到了近100%,其输出功率最高可达1.9 W,平均输出功率稳定性优于1%.实验表明平均输出功率、重复频率和脉冲宽度随泵浦功率增加而上升.     

HPLC测定中药渣中人参皂苷Rg_1、Re与Rb_1含量

建立了一种利用反相高效液相色谱检测中药渣中人参皂苷Rg_1、Re和Rb_1含量的分析方法。考察了提取试剂、提取温度、提取溶剂倍量、提取时间对提取效果的影响,最终将样品以10倍体积的70%甲醇于40℃水浴中超声提取0.5 h。采用Zorbax SB-C_(18)(4.6 mm×150 mm,5μm)柱分离,以乙腈和水为流动相进行梯度洗脱,流速为1.0 m L/min,进样量为20μL,柱温为20℃,检测波长为203 nm,采用外标法定量。在该条件下,人参皂苷Rg_1、Re、Rb_1分别在18.74~257.61、37.48~468.54、3.88~96.93 mg/L范围内线性关系良好(r~20.999)。人参皂苷Rg_1、Re和Rb_1的定量下限(S/N=10)分别为17.69、13.94、1.14 mg/L。3个不同浓度的加标回收率为89.1%~107%,相对标准偏差(RSD,n=3)为0.6%~4.1%。该方法具有操作简便快捷、检测灵敏度高等特点。