基于铌酸锂薄膜波导的电光调谐光栅辅助定向耦合器研究  

Electro-optic Tunable Grating-assisted Optical Waveguide Directional Coupler in Lithium Niobate on Insulator

作　　者：李俊慧 姚昊 邓佳瑶 陈开鑫 LI Junhui;YAO Hao;DENG Jiayao;CHEN Kaixin(School of Optoelectronic Science and Engineering,University of Electronic Science and Technology of China,Chengdu 611731,China)

机构地区：[1]电子科技大学光电科学与工程学院,成都611731

出　　处：《光子学报》2023年第10期189-198,共10页Acta Photonica Sinica

基　　金：国家自然科学基金(No.62075027);国家重点研究发展计划(No.2021YFB2800104);深圳市关键技术研发计划(No.JSGG20210802154413040)。

摘　　要：提出并实验研究了一种基于铌酸锂薄膜光波导的电光调谐的光栅辅助定向耦合器。该耦合器由单模与双模脊形波导及制作于双模波导侧壁的长周期光栅构成。长周期光栅的引入补偿了单模与双模波导中基模的相位失配,可在共振波长实现两波导中基模的高效耦合。进一步地,在双模脊形波导两侧制作调谐电极实现了高速、低驱动电压的电光调谐功能。优化了器件的制作工艺,并采用单次干法刻蚀将耦合器的光栅与波导同步制作于X切铌酸锂薄膜上。测试结果表明所制作的器件在1595.3 nm波长处实现了14.8 dB的隔离度,其电光调谐效率为0.38 nm/V(1595.3 nm~1599.0 nm),热光调谐效率为0.14 nm/℃(25℃~50℃)。该器件可用于实现可调谐滤波、滤模、电光调制及高灵敏度温度传感等功能。Grating Assisted Directional Coupler(GADC)is an important optical waveguide device because it is capable of achieving efficient coupling between the two modes having mismatched phase.GADC provides a new way to improve the performances of the coupler and the grating.Due to its compact structure,easy integration,versatility,and good wavelength selectivity,GADC is now widely used in various scenarios,such as codirectional coupler,optical add-drop filter,tunable delay line,wavelength division multiplexer,mode division multiplexer,filter,mode filter,and so on.However,most of these devices do not have tunability,while tunability is the key for improving the device performance,realizing device reconfiguration,and enlarging the device fabrication tolerance.Up to now,the tunability of optical waveguide devices are usually realized based on the Electro-Optic(EO)and the Thermo-Optic(TO)effects.Among them,EO tuning is more fascinating due to its high tuning speed and low power consumption.Lithium Niobite(LN)On Insulator(LNOI),a newly emerging integrated optics platform in recent years,not only keeps the excellent EO,acousto-optic,and nonlinear optical properties of LN,but also enables high-index-contrast and hence high-confinement waveguide,which makes it an excellent platform for developing compact and high-performance EO devices.In this paper,a high-performance electro-optical tunable GADC in LNOI is proposed and demonstrated.Our proposed device consists of an Asymmetric Directional Coupler(ADC),a sidewall Long Period Waveguide Grating(LPWG),and a set of electrodes.The ADC is composed of a Single-Mode Waveguide(SMW)and a Two-Mode Waveguide(TMW),and both are rib waveguides with identical etch depth.The LPWG is formed on the inner side of the ridge of the TMW.Both ADC and the LPWG are formed with the Inductively Coupled Plasma(ICP)process simultaneously.Due to the large birefringence of LN,the LPWG can not meet the phase matching of the two polarized fundamental modes in the SMW and the TMW simultaneously,thus it is designed

关 键 词：光栅辅助的定向耦合器 长周期波导光栅 铌酸锂薄膜 电光调谐 热光调谐 

分 类 号：TN256[电子电信—物理电子学]