共查询到18条相似文献,搜索用时 125 毫秒
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准相位匹配(QPM)技术研究新进展 总被引:5,自引:1,他引:4
准相位匹配是一种人为地制备周期结构以实现非线性频率转换技术,它拓宽了非线性晶体应用范围,提高了频率转换效率。本文详细介绍了准相位匹配主要技术优势,并描述周期极化畴反转技术,这一当前普遍用来制备准相位匹配非线性晶体的实验方法,同时总结了这一领域国内外研究的最新进展。 相似文献
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在光子晶体的一维周期极化结构中,其频率转换只允许在单一方向上进行,而二维准相位匹配光子晶体比一维准相位匹配光子晶体具有更多方向上的倒格矢。故可实现多方向、多波长的同时倍频。文中在各向异性非线性FDTD算法的基础上。对周期为6.82方形格子二维周期性极化的LiNbO3非线性光子晶体进行了分析,给出了利用一阶准相位匹配来实现1.06μm波长的二倍频方法。 相似文献
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扫描电镜加工铌酸锂晶体电畴反转光栅的研究 总被引:3,自引:0,他引:3
本文简单介绍了非线性晶体相位匹配和铌酸锂光波导准相位匹配倍频原理,开展了扫描电子显微镜电子束辐照反转极化实验,分析了实验结果,摸索出合适的工艺条件,证明利用扫描电镜可以加工出满足准相位匹配条件的电畴反转我栅。 相似文献
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准相位匹配有利于实现高效的自发参量下转换,它由非线性晶体的极化周期和依赖于温度的折射率决定。为了确定特定波长处所需的晶体温度,需要测量相位匹配波长随晶体温度的变化关系。单色仪的传统测量方法具有测量精度较低且耗时长等缺点。提出了一种实验方法,该方法能快速准确测量纠缠光子相位匹配波长随晶体温度变化的关系。在信号和闲置光路中先后加入色散元件,通过测量纠缠光子对到达时间关联峰值处的时间延迟随晶体温度的变化关系,利用波长到时间的映射关系将其转化为波长随晶体温度的变化关系。给出了周期极化铌酸锂(PPLN)波导和周期极化磷酸氧钛钾(PPKTP)晶体的实验测量结果,测量精度优于0.1 nm,测量时间约为几分钟。测量精度受限于单光子探测器的抖动时间和色散元件色散量的大小。原则上,抖动时间越小,色散量越大,测量精度越高。最后讨论了Sellmeier方程计算的结果与实验结果存在差异的可能原因。所提方法可以用来校准相位匹配波长与晶体温度的关系及极化周期,并有望实现温度依赖的Sellmeier方程的修正或改进。 相似文献
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基于周期极化晶体的准相位匹配理论,对周期极化RbTiOAsO4(PPRTA)晶体的倍频允许参量的调谐特性进行了理论分析.通过数值模拟计算,获得了PPRTA晶体的极化反转光栅周期、晶体温度和基频光波长的允许参量的调谐曲线,并且与PPKTP晶体和PPLN晶体的倍频允许参量的调谐特性进行了比较.当晶体长度10 mm时,在相同条件下,PPRTA晶体的允许极化反转周期△A和允许温度调谐范围△tmax最大,分别对应的基频波长为2.743 3 μm和2.247 4 μm,PPLN晶体的允许波长调谐范围△λmax最大,对应的基频波长为2.704 6 μm.理论结果为周期极化晶体的准相位匹配倍频实验提供了依据. 相似文献
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Paul A. Gibson E.A. Xiaoshi Zhang Lytle A. Popmintchev T. Xibin Zhou Murnane M.M. Christov I.P. Kapteyn H.C. 《Quantum Electronics, IEEE Journal of》2006,42(1):14-26
Coherent beams at soft X-ray (SXR) wavelengths can be generated using extreme nonlinear optics by focusing an intense laser into a gas. In this paper, we discuss phase-matching and quasi-phase-matching techniques that use gas-filled modulated waveguides to enhance the frequency conversion process. This leads to the generation of SXR beams that are both spatially and temporally coherent. 相似文献
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Webjorn J. Siala S. Nam D.W. Waarts R.G. Lang R.J. 《Quantum Electronics, IEEE Journal of》1997,33(10):1673-1686
This paper reviews nonlinear quasi-phase-matching (QPM) waveguides and laser diodes with application to conversion of infrared laser diode wavelengths to the visible. The discussion of nonlinear QPM waveguides includes Ti-diffusion poled and E-field poled LiNbO3 and KTP waveguides. Up to 25 mW of blue output power has been demonstrated for 120-mW infrared power injected into a nonlinear waveguide. Semiconductor laser sources suitable for frequency doubling are discussed, including distributed Bragg reflection (DBR) lasers operating at up to 200 mW output power, master oscillator power amplifiers with over 1 W output power, and wavelength-tunable flared semiconductor lasers with over 0.5 W output. A compact blue laser with 1-4 mW output power at 425-nm wavelength has been demonstrated based on a DBR laser frequency doubled in a nonlinear waveguide 相似文献
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We present a quantitative theory of nonlinear frequency conversion in stacks of crystals where the phase mismatch due to dispersion is compensated by changing the sign of the nonlinear coupling coefficient in successive crystals-a method first proposed by Armstrong et al. We include pump depletion in our calculations of the second harmonic generation and sum and difference frequency generation. We start with ideal stacks in which the crystal lengths are tailored to achieve perfect phase compensation. When the conversion in each coherence length is small, all crystal lengths tend to equal the coherence lengthpi/Deltak . Frequency conversion in such stacks is well approximated by that in an equivalent phase-matched crystal with the nonlinear coupling coefficient reduced by a factor of2/pi . The effect of systematic as well as random departures in crystal lengths are studied with special attention to the evolution of the relative phase. We show that with appropriate choice of the signs of the nonlinear coupling coefficient in various crystals, high efficiency frequency conversion should be possible using practically any sufficiently large set of nonlinear crystals. The theory of second harmonic generation in periodic stacks and in rotationally twinned crystals of zinc-blend structure is described in detail. 相似文献
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We present a theoretical analysis of second-order nonlinear difference frequency generation (DFG) in a generalized mirrorless quasi-phase-matching (QPM) frame, aimed at a comparison of counterpropagating DFG configuration (CDFG) to other DFG schemes, in view of all-optical processing applications. Field nonlinear coupling equations have been numerically solved under the hypothesis of phase-matched interaction. The evolution of propagating fields within the material and the wavelength conversion efficiency have been calculated in dependence of operating parameters. The increased complexity in the evolution of amplitude and phase for fields interacting in CDFG with respect to forward-propagating DFG (FDFG) is at the basis of a dramatic increase in the wavelength conversion efficiency under particular settings of device parameters 相似文献
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Waveguide quasi-phase matching second-harmonic generation (QPM-SHG) using an organic molecular crystal as a nonlinear material was demonstrated for the first time. The device is constructed with an array of SiN channel guides with grooves of a fan-out grating pattern and mNA single crystal grown over the waveguides. A normalized efficiency of 0.04%/W was obtained in an experiment involving frequency doubling of CW Nd:YAG laser light 相似文献
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高功率窄线宽光纤激光器具有光束质量好、结构紧凑等优点,在相干合成、光谱合成以及非线性频率变换等领域具有广泛的应用前景,基于窄线宽光纤激光相干合成、光谱合成的激光系统性能指标已经超越单束激光的最高性能,基于窄线宽光纤激光非线性频率变换的激光也实现了同类波段激光的最高性能。分析窄线宽光纤激光功率提升同时保持光束质量过程中产生的物理机制和面临的技术挑战,详细介绍学校课题组在高功率窄线宽光纤激光方面取得的代表性成果,特别是高光束质量的7 kW级非线偏振窄线宽激光和5 kW级线偏振窄线宽激光,不仅是同类激光的最高功率值,也逼近了同等条件下非窄线宽光纤激光的功率极限。根据近年来理论研究和技术攻关结果,结合国内外研究现状,对高功率窄线宽光纤激光未来几个发展趋势进行预判。 相似文献
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Advances in nonlinear crystals and pumps prepare optical parametric devices (OPDs) for service as a reliable, broadly tunable light source. Fundamental optical parametric processes in crystals are examples of nonlinear, multibeam mixing processes. The processes that have recently experienced an explosion of interest involve conversion of a pump photon at high frequency into two photons at lower frequencies. The spectrum of frequencies in the downconverted beams is not restricted by this relation 相似文献