基于空芯微结构光纤拉曼探针的实验研究

表面增强拉曼散射(SERS)技术可有效增强样品分子的拉曼信号,对生物分子检测具有较高的灵敏性,因此在生化方面有着许多潜在的应用.而将空芯微结构光纤与SERS技术相结合不仅能够远端实时、分布式地检测,同时还可以增加光场与待测物的有效作用面积,减少传统光纤探针无法避免的石英背景信号等问题.本文基于空芯微结构光纤进行SERS探针的制备及性能测试研究,利用真空物理溅射法在空芯光纤内镀纳米Ag膜,从而制备成SERS探针,通过实验检测不同浓度的罗丹明6G (R6G)酒精溶液的拉曼信号.结果表明,在探针的近端正面成功探测到了浓度低至10^(-9)mol/L的R6G拉曼信号,在探针的远端反面探测到的浓度可小于10^(-6)mol/L.该实验结果为研究高灵敏度的SERS探针提供了一种新的手段.

Flat Supercontinuum Generation within the Telecommunication Wave Bands in a Photonic Crystal Fiber with Central Holes

Flat supercontinuum in the telecommunication wave bands of E+S+C is generated by coupling a train of femtosecond pulses generated by a mode-locked Ti:sapphire laser into the fundameutal mode of a photonic crystal fiber with central holes fabricated in our lab. The pulse experiences the anomalous dispersion regime,and the soliton dynamic effect plays an important role in supercontinuum generation.The output spectrum in the wavelength range of 1360 1565nm does not include significant ripples due to higher pump peak power,and the normalized intensity shows less fluctuation.

Widely Wavelength-Tunable Blue-Shifted Dispersive Waves for Broadband Visible Wavelength Generation in a Photonic Crystal Fiber Cladding

Blue-shifted dispersive waves(DWs)are efficiently generated from the red-shifted solitons by coupling the 120 fs pulses into the fundamental mode of the multi-knots of a photonic crystal fiber cladding.When the femtosecond pulses at the wavelength of 825 nm and the average power of 300 mW are coupled into knots 1–3,the conversion efficiencyηDW of 32%and bandwidth BDW of 50 nm are obtained.The ultrashort pulses generated by the DWs can be tunable over the whole visible wavelength by adjusting the wavelengths of the pump pulses coupled into different knots.It can be believed that this widely wavelength-tunable ultrashort visible pulse source has important applications in ultrafast photonics and resonant Raman scattering.

Ultraviolet Continuum Generation in the Fundamental Mode of Photonic Crystal Fibers

The ultraviolet continuum generation in the fundamental mode of photonic crystal fibers designed and fabricated in our lab are experimentally demonstrated.When the pump works in the normal dispersion regions of 780 nm and 830 nm,and the average powers increase from 100 to 500 m W,anti-Stokes signals can be efficiently generated based on the phase-matched degenerate four-wave mixing.The cross-phase modulation between the pump and the generated anti-Stokes signals can effectively extend the continuum into the ultraviolet wavelength range.This can provide an efficient light source for ultraviolet photonics and spectroscopy.

冉雪梦补肾健脾化痰祛瘀法治疗肥胖型多囊卵巢综合征经验

多囊卵巢综合征在妇科疾病中较为常见,肥胖是其常见临床表现,发病机制未明,并发症较多且容易反复。冉雪梦认为其发病与脾肾功能失调关系密切,以“补肾健脾、化痰祛瘀”辨证施治二十余年,见解较独到,临床效果佳。笔者从辨证治疗、分期治疗和周期治疗三方面总结冉雪梦治疗肥胖型多囊卵巢综合征临床经验。

极端干旱对陆地生态系统的影响:进展与展望

作为地球表层重要的组成部分,陆地生态系统是人类生存和发展的重要场所。进入21世纪以来,气候变化导致干旱事件发生的强度、频度和持续时间显著增加,对陆地生态系统带来深远的影响,严重制约甚至威胁人类社会的可持续发展。因此,开展极端干旱对陆地生态系统影响的研究并评估其生态风险效应,是当前全球变化领域研究的重点问题。该文从植物生理生态过程、生物地球化学循环、生物多样性以及生态系统结构和功能4个方面综述了极端干旱对陆地生态系统的影响,并对当前的研究热点进行探讨,深度剖析当前研究中存在的难点问题和未来可能的发展方向,以期为未来开展干旱对陆地生态系统影响的观测与预测研究提供参考,为在未来干旱影响下加强陆地生态系统风险评估和管理提供新思路。