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用标量有限元方法计算了周期性极化的铌酸锂光波导中模折射率和模场分布,并在计算中引入铌酸锂晶体折射率与温度变化的关系,分析了准位相匹配铌酸锂波导倍频效率与极化反转光栅周期、基频光波长、波导器件温度等关系.理论分析与实验结果符合得很好.在此基础上,分析了波导制作参数与倍频效率、光栅周期与晶体温度,以及温度带宽与光栅通光方向长度等关系,进而对铌酸锂波导倍频器件进行优化设计.
关键词:
铌酸锂
光波导
准位相匹配
有限元 相似文献
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半导体激光直接倍频的488nm蓝光激光器 总被引:4,自引:0,他引:4
利用波导型准相位匹配周期极化反转铌酸锂(PPLN)晶体直接倍频波长为976 nm的连续半导体激光二极管,在最佳晶体工作温度(28℃)下,获得了波长为488 nm的连续蓝光输出,最大输出功率大于20 mW。所用的晶体尺寸为8 mm×1.4 mm×1 mm,波导截面为4.5μm×3.5μm,极化周期为5.2μm。研究了波导型周期极化反转铌酸锂晶体的倍频效率与温度的关系,与普通的周期极化反转铌酸锂相比,倍频效率与温度关系的敏感度较低。同时,由于晶体可以在室温下工作,简化了加温与温控部件,提高了整机的工作效率。在此实验的基础上,制成了一台小型的全固态488 nm连续蓝光激光器。 相似文献
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提出一种将质子交换技术和刻蚀技术结合的体铌酸锂波导和器件加工方案,基于质子交换的铌酸锂晶体相变特性改变,降低了质子交换区直接刻蚀难度,结合质子交换的纵向折射率改变和刻蚀波导的横向结构改变,波导尺寸显著降低,采用粒子群算法优化波导尺寸,最小可达2.5μm。基于该工艺方案设计了中心波长为1550 nm、四通道且通道间隔为400 GHz的阵列波导光栅,该阵列波导光栅的传输损耗约为6 dB,相邻通道间串扰均低于22 dB,整体尺寸仅为850μm×620μm,在高密度铌酸锂光子集成互连等场景具有较大的应用潜力。 相似文献
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钛扩散铌酸锂光波导是应用很广的一种光波导器件,知道铌酸锂扩散波导的有效折射率和扩散后表面折射率对于进一步设计波导和分析波导特性很有意义。本文用在0.6328μm可见光下测量波导的有效折射率,利用色散方程推导出铌酸锂波导在其它各个波长的折射率。介绍了通过z切的折射率修正到x切向下的折射率的方法,该方法可以推广到任意切向。此外,还给出了计算波导表面折射率方法,即可以计算出波导扩散后形成的最大折射率差。文中给出了在1.55μm下x切y传铌酸锂波导有效折射率的计算实例。 相似文献
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准相位匹配扇形光栅铌酸锂光波导倍频绿光输出 总被引:2,自引:2,他引:0
采用外加电场极化方式对具有扇形光栅的 0 .5mm厚Z切铌酸锂晶体进行极化反转 ,制成了退火质子交换光波导。极化反转周期为 5 .8μm~ 6 .2 μm ,采用Nd∶YAG激光器输出的 1.0 6 4 μm连续激光为基频光波 ,实现了0 .5 32 μm倍频绿光输出 ,相互作用长度为 4mm ,耦入波导的基频光波功率为 10mW ,获得了 2 0 μW的绿色倍频光输出 ,归一化转换效率为 12 5 % (W·cm2 )。 相似文献
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研究了质子交换铌酸锂多模波导中的非线性上转换Cerenkov辐射,包括同一导模的直接Cerenkov倍频辐射和不同导模之间耦合产生的Cerenkov和频辐射.实验测得各个点的Cerenkov辐射角,实验值与理论计算结果符合得很好. 相似文献
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《Optics Communications》2002,201(1-3):179-190
The coupled-mode equation in dissipative waveguides in Cherenkov configuration has been detailedly discussed for the first time, to our knowledge. Based on this equation, Cherenkov second harmonic generation (SHG) and Cherenkov nonlinear phase shift (NPS) caused by Cherenkov cascading second order nonlinear (CSON) effects have been analyzed and optimized comprehensively and systematically by an analytical method, taking into account both the conversion depletion and the waveguide loss, and the analytical expressions for Cherenkov SHG and NPS has been presented. The dependence of the NPS and the conversion efficiency on varied parameters, such as the waveguide thickness, the fundamental wavelength, the input fundamental power and the temperature, has been discussed completely. The results show that a large enough NPS (>10π) can be attained for nondissipative waveguides with a very small depletion of the fundamental power, at the same time, this Cherenkov CSON configuration has some advantages over the quasi-phase matching CSON configuration, e.g., the much looser tolerances of the waveguide parameters and the noncollinear feature of the fundamental wave and the second harmonic wave, these characteristics make the Cherenkov CSON configuration a promising direction to realize all-optical devices. 相似文献
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Carbon ion irradiation and precise diamond blade dicing are applied to fabricate Nd:GdCOB ridge waveguides. The propagation properties of the fabricated Nd:GdCOB waveguides are investigated through experiments and theoretical analysis. Micro-Raman analysis reveals that the Nd:GdCOB crystal lattice expands during the irradiation process. Micro-second harmonic spectroscopic analysis suggests that the original nonlinear properties of the Nd:GdCOB crystal are greatly enhanced within the waveguide volume. Under pulsed 1064 nm laser pumping, second harmonic generation (SHG) at 532 nm has been achieved in the fabricated waveguides. The maximum SHG conversion efficiencies are determined to be ~ 8.32 %·W-1 and ~ 22.36 %·W-1 for planar and ridge waveguides, respectively. 相似文献
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Efficient three-wave mixing devices have numerous applications, including wavelength conversion, dispersion compensation, and all-optical switching. Second-harmonic generation (SHG) is a useful diagnostic for near-degenerate operation of these devices. With buried waveguides formed in periodically poled lithium niobate by annealed and reverse proton exchange, we demonstrate what is believed to be the highest normalized conversion efficiency (150%/W cm(2)) for SHG in the 1550-nm communications band reported to date. 相似文献
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We demonstrate second-harmonic generation (SHG) from sub-micrometer-sized AlGaAs/AlxOy artificially birefringent waveguides. The normalized conversion efficiency is the highest ever reported. We further enhanced the SHG using a waveguide-embedded cavity formed by dichroic mirrors. Resonant enhancements as high as approximately 10x were observed. Such devices could be potentially used as highly efficient, ultracompact frequency converters in integrated photonic circuits. 相似文献
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C. Deng J. W. Haus A. Sarangan A. Mahfoud C. Sibilia M. Scalora A. Zheltikov 《Laser Physics》2006,16(6):927-947
Enhanced second-harmonic generation (SHG) conversion efficiency was theoretically predicted in waveguide geometry with coupling to a one-dimensional grating photonic band gap (PBG). We report a series of experiments using samples made with lithium niobate. A waveguide was fabricated near the surface by applying the proton-exchange technique. The characteristics of waveguide modes were determined by several techniques: prism coupling, diffraction, and Cherenkov radiation. The WKB method was used to analyze the results. Ultraviolet laser lithography was applied to make PBG gratings on the sample. We further investigated Cherenkov second-harmonic generation (CSHG), i.e., SHG radiated into the substrate, under the condition of a band-edge PBG resonance in the waveguides. The SHG inside planar waveguides was also experimentally investigated. We fabricated waveguides with multiple pump modes and found that the second mode was more efficient in enhancing the second harmonic signal. This result is explained by our model. Several samples were investigated in detail; the highest conversion efficiency of CSHG with a PBG was enhanced around 50 times above the CSHG signal without a PBG. A numerical model was constructed with parameters calculated from our sample characterization data to interpret the experimental results. 相似文献
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We demonstrate ultrasensitive intensity autocorrelation measurements of subpicosecond optical pulses in the telecommunication band by using aperiodically poled lithium niobate (A-PPLN) waveguides. The tightly confined optical beam in the waveguides and the chirped poling period facilitate simultaneous high second-harmonic generation (SHG) efficiency and broad phase-matching (PM) bandwidth. The resulting measurement sensitivity is 3.2 x 10(-7) mW2, approximately 500 times better than the previous record for intensity autocorrelations. We also show that chirped A-PPLN waveguides retain nearly the same SHG efficiency as the unchirped guide as long as the PM bandwidth is not significantly broader than the input spectrum. 相似文献
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We investigate the thermo-optic effects on second harmonic generation (SHG) in AlGaAs/AlO(x) microring (MR) waveguides. We show that SHG can be utilized to enhance the thermal sensitivity of MRs. This sensitivity makes this structure appropriate for thermal modulation and switching of optical signals or temperature sensing. 相似文献
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A. C. Busacca R. L. Oliveri A. C. Cino S. Riva-Sanseverino A. Parisi G. Assanto 《Laser Physics》2007,17(6):884-888
The compatibility of low concentration (α-phase) proton exchange channel waveguides with electric field surface periodic poling of congruent lithium niobate (SPPLN) crystals has been experimentally demonstrated. With such waveguides, we obtained ultraviolet second harmonic generation (SHG) by first order quasi-phase-matching (QPM), a result made possible by the fabrication, on Z-cut LN crystals, of periodic structures with a pitch down to 750 nm. Nonlinear copropagating QPM-SHG measurements have been carried out on such structures. The pump source was a Ti:sapphire laser with a tunability range of 700–980 nm and a 40 GHz linewidth. We have measured UV continuous wave light at 390 nm by means of a lock-in amplifier and a photodiode with an enhanced response in the UV. The measured conversion efficiency was about 1% W?1 cm?2. 相似文献
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Y.N. Korkishko V.A. Fedorov A.N. Alkaev F. Laurell 《Applied physics. B, Lasers and optics》2001,73(5-6):519-522
A detailed correlation between the fabrication conditions, crystallographic phase state of HxLi1-xTaO3 waveguides and second-order optical non-linearity has been investigated by using reflected SHG measurements from the polished
waveguide end face. The non-linearity, strongly reduced after the initial proton exchange, is found to be restored and even
increased after annealing. However, this apparent increase in the non-linearity is accompanied by a strong degradation of
the quality of the SHG reflected beam in the region of the initial as-exchanged waveguide due to beam scattering. The high
temperature proton exchange technique has been shown to produce high-quality α-phase waveguides with essentially undegraded
non-linear optical properties. There is no phase transition when the α-phase waveguides are fabricated by direct exchange.
This phase presents the same crystalline structure as that of LiTaO3 and maintains the excellent non-linear properties of the bulk material. The results obtained are important for the design,
fabrication and optimization of guided-wave non-linear optical devices in LiTaO3.
Received: 21 May 2001 / Published online: 23 October 2001 相似文献