Thin-film lithium niobate(TFLN)modulators have gained significant attention for their high electro-optic modulation efficiency and large bandwidth.However,achieving efficient coupling to single-mode fibers remains a c...Thin-film lithium niobate(TFLN)modulators have gained significant attention for their high electro-optic modulation efficiency and large bandwidth.However,achieving efficient coupling to single-mode fibers remains a challenge.In this work,we present a large-bandwidth TFLN modulator with a low fiber-to-fiber loss,employing grating couplers with metal mirrors for perfectly vertical coupling,which facilitates wafer-scale testing and packaging.The modulator with electrodes and metal mirrors is initially fabricated on a lithium niobate(LN)-on-insulator with a silicon substrate,followed by bonding to a quartz wafer using UV adhesive,with subsequent removal of the silicon substrate.By incorporating periodic capacitively loaded traveling-wave electrodes,the modulator achieves high modulation efficiency while maintaining a large bandwidth.The final device demonstrates a low fiber-to-fiber loss of 6.5 d B,a 3-dB bandwidth exceeding 67 GHz,and a half-wave voltage of 3.8 V in a 7 mm long modulation section.Additionally,successful data transmission using on-off keying modulation at rates up to 100 Gbit/s is achieved.The proposed modulator is compatible with wafer-scale production and holds promising potential for high-capacity,low-loss optical communication systems.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62135012 and 62105107)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(No.2021R01001)+1 种基金the Basic and Applied Basic Research Foundation of Guangdong Province(Nos.2024A1515011710 and 2022A1515011258)the Guangdong Provincial Key Laboratory of Optical Information Materials and Technology(No.2023B1212060065)。
文摘Thin-film lithium niobate(TFLN)modulators have gained significant attention for their high electro-optic modulation efficiency and large bandwidth.However,achieving efficient coupling to single-mode fibers remains a challenge.In this work,we present a large-bandwidth TFLN modulator with a low fiber-to-fiber loss,employing grating couplers with metal mirrors for perfectly vertical coupling,which facilitates wafer-scale testing and packaging.The modulator with electrodes and metal mirrors is initially fabricated on a lithium niobate(LN)-on-insulator with a silicon substrate,followed by bonding to a quartz wafer using UV adhesive,with subsequent removal of the silicon substrate.By incorporating periodic capacitively loaded traveling-wave electrodes,the modulator achieves high modulation efficiency while maintaining a large bandwidth.The final device demonstrates a low fiber-to-fiber loss of 6.5 d B,a 3-dB bandwidth exceeding 67 GHz,and a half-wave voltage of 3.8 V in a 7 mm long modulation section.Additionally,successful data transmission using on-off keying modulation at rates up to 100 Gbit/s is achieved.The proposed modulator is compatible with wafer-scale production and holds promising potential for high-capacity,low-loss optical communication systems.
