低驱动、高调制X-Cut铌酸锂电光调制器的优化设计  

Optimized Design of Low Driving and High Modulation X-Cut LiNbO_3 Electro-Optical Modulator

作　　者：梁凤超 李敏[2] 吴东岷[2] Liang Fengchao;Li Min;Wu Dongmin(School of Physics and Optoelectronic Engineering,Shandong University of Technology,Zibo,Shandong 255000,China;International Laboratory,Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences Suzhou,Jiangsu 215123,China)

机构地区：[1]山东理工大学物理与光电工程学院,山东淄博255000 [2]中国科学院苏州纳米技术与纳米仿生研究所国际实验室,江苏苏州215123

出　　处：《光学学报》2018年第7期169-175,共7页Acta Optica Sinica

基　　金：国家自然科学基金青年科学基金(61505241)

摘　　要：利用定向耦合器代替Y形分支结构,在X-cut铌酸锂(LN)基底上设计了一款具有低驱动电压、高调制参数的马赫-曾德尔(M-Z)型电光调制器。采用有限元法对定向耦合器的原理及影响因素进行了详细分析和精确计算,并对电光调制器的关键结构参数进行了优化。结果表明:光波沿着定向耦合器传播时,能量在两波导中来回交替,呈正弦和余弦函数分布,并且耦合长度随着其间距的增大而快速增大。在调制臂长为3cm,光波长为1550nm的情况下,单臂调制所获得的半波电压Vπ为2.22V,调制参数S21为-51.13dB。通过对调制臂进行截面分析,给出了电场Ex分量、电位移矢量Dx分量和光模分布,并求得重叠积分因子为0.486。同时还表明脊形波导结构有利于提高电光作用效率。当脊高为1μm时,重叠积分因子为0.714,相较于平板波导,其电光重叠积分因子提高了46.91%。A Mach-Zehnder（M-Z）electro-optical modulator with low driving voltage and high modulation parameters is designed on the X-cut Lithium Niobate（LN）substrate by using a directional coupler instead of traditional Y-shaped branch structure.The working principle and major factors of directional coupler are analyzed and calculated precisely by the finite element method.The major structural parameters of the electro-optic modulator are optimized.The results show that when the light wave propagates along the directional coupler,the energy is alternated back and forth in the two waveguides with a distribution of sine and cosine functions.At the same position,the coupling length increases rapidly with the increase of the gap.When the electro-optical modulation arm length is 3 cm and the optical wavelength is 1550 nm,the half-wave voltage Vπobtained by the single-arm modulation is 2.22 Vand the modulation parameter S21 is-51.13 dB.With the section analysis of modulation arms,the electric field Excomponent,the electric displacement vector Dxcomponent and the optical mode distribution are given,and the integral overlap factor is 0.486.It also shows that the ridge waveguide structure can effectively improve the electro-optic efficiency.When the ridge height is 1μm,the overlap integral factor is 0.714,and the electro-optical overlap integral factor of it is 46.91%higher than the slab waveguide.

关 键 词：集成光学 有限元法 光波导 定向耦合器 电光调制器 

分 类 号：TN256[电子电信—物理电子学]