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.     

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。     

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.     

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.     

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。     

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.     

气相色谱法测定大气中的CO、CO_2以及低级烃类物质

建立了运用气相色谱对大气中一氧化碳、二氧化碳以及3种低级烃类甲烷、乙烯和乙炔进行同时分析的方法。气相色谱分析系统由自动进样器、1个十通阀协同1个六通阀,以及1个十通阀协同1个四通阀组成,可以实现进样、分离和反吹功能。HP-PLOT Q开口毛细管柱用于5种气体的分离,柱后连接热导检测器;分离完成后,一氧化碳和二氧化碳通过甲烷转化炉中的镍催化作用转化为甲烷,用氢火焰离子化检测器进行检测。5种目标分析物在9 min内完全分离。一氧化碳、甲烷、二氧化碳、乙烯以及乙炔的线性范围分别为3.3~4 990.0、3.3~5 010.0、6.6~4 990.0、4.2~5 080.0、3.9~5 030.0μmol/mol,检出限为1.0~2.0μmol/mol,相关系数不低于0.997,相对标准偏差(RSD,n=5)不大于3.5%。该方法简单、准确,可操作性强。     

Diode-Pumped Passive Q-Switched 946-nm Nd：YAG Laser with 2.1-W Average Output Power

We demonstrate a diode-pumped passive Q-switched 946nm Nd: YAG laser with a diffusion-bonded composite laser rod and a co-doped Nd, Cr:YAG as saturable absorber. The average output power of 2.1 W is generated at an incident pump power of 14.3 W. The peak power of the Q-switched pulse is 643 W with 80kHz repetition rate and 40.8 ns pulse width. The slope efficiency and optical conversion efficiency are 17.6% and 14.7%, respectively.     

高效液相色谱法测定土壤中香豆素类灭鼠药残留

建立了测定土壤中杀鼠灵、杀鼠醚、溴敌隆、氟鼠灵、溴鼠隆5种香豆素类灭鼠药残留量的柱后衍生荧光检测高效液相色谱方法。样品在加入内标物氯杀鼠灵后用丙酮-氨水-甲醇（体积比为100：3：100）混合液提取,浓缩的提取液用5 mL正己烷-氯仿（体积比为3：1）混合液溶解,NH₂固相萃取小柱净化,用15 mL 50 mmol/L四丁基磷酸二氢铵甲醇溶液洗脱分析物,移除溶剂,用甲醇-0.25%（体积分数）乙酸水溶液（体积比为3：2）混合液溶解,过滤后,经高效液相色谱分离,以甲醇-氨水-水（体积比为1：1：8）混合液为衍生试剂进行柱后衍生,采用荧光检测器检测。杀鼠灵、杀鼠醚、溴敌隆、氟鼠灵、溴鼠隆5种鼠药在0.02～10.00 mg/L范围内线性关系良好,相关系数均大于0.999,定量限（LOQ,S/N=10）为2.2～18.5 μg/L。在0.1～0.3 mg/kg添加水平内,5种灭鼠药的回收率为94.6%～118.0%,相对标准偏差（RSD）为0.8%～10.2% （n=3）。实验结果表明该方法灵敏、准确,重复性好。