Whispering-gallery-mode(WGM)microresonators can greatly enhance light-matter interaction,making them indispensable units for frequency conversion in nonlinear optics.Efficient nonlinear wave mixing in microresonators ...Whispering-gallery-mode(WGM)microresonators can greatly enhance light-matter interaction,making them indispensable units for frequency conversion in nonlinear optics.Efficient nonlinear wave mixing in microresonators requires stringent simultaneous optical resonance and phase-matching conditions.Thus,it is challenging to achieve efficient frequency conversion over a broad bandwidth.Here,we demonstrate broadband second-harmonic generation(SHG)in the x-cut thinfilm lithium niobate(TFLN)microdisk with a quality factor above 107by applying the cyclic quasi-phase-matching(CQPM)mechanism,which is intrinsically applicable for broadband operation.Broadband SHG of continuous-wave laser with a maximum normalized conversion efficiency of~15%/m W is achieved with a bandwidth spanning over 100 nm in the telecommunication band.Furthermore,broadband SHG of femtosecond lasers,supercontinuum lasers,and amplified spontaneous emission in the telecommunication band is also experimentally observed.The work is beneficial for integrated nonlinear photonics devices like frequency converters and optical frequency comb generator based on second-order nonlinearity on the TFLN platform.展开更多
Optical frequency conversion based on the second-order nonlinearity(χ^((2))) only occurs in anisotropic media(or at interfaces) and thus is intrinsically polarization-dependent. But for practical applications, polari...Optical frequency conversion based on the second-order nonlinearity(χ^((2))) only occurs in anisotropic media(or at interfaces) and thus is intrinsically polarization-dependent. But for practical applications, polarization-insensitive or independent operation is highly sought after. Here, by leveraging polarization coupling and second-order nonlinearity, we experimentally demonstrate a paradigm of TE/TM polarization-independent frequency upconversion, i.e., sum frequency generation, in the periodically poled lithium niobate-on-insulator ridge waveguide. The cascading of quasi-phase-matched polarization coupling and nonlinear frequency conversion is exploited. With a proper transverse electric field, TE and TM mode fundamental waves can be frequency-upconverted with an equal efficiency in the frequency converter. The proposed method may find ready application in all-optical wavelength conversion and upconversion detection technologies.展开更多
We design and fabricate an unbalanced Mach–Zehnder interferometer(MZI)via electron beam lithography and inductively coupled plasma etching on lithium niobate thin film.The single unbalanced MZI exhibits a maximum ext...We design and fabricate an unbalanced Mach–Zehnder interferometer(MZI)via electron beam lithography and inductively coupled plasma etching on lithium niobate thin film.The single unbalanced MZI exhibits a maximum extinction ratio of 32.4 dB and a low extra loss of 1.14 dB at the telecommunication band.Furthermore,tunability of the unbalanced MZI by harnessing the thermo-optic and electro-optic effect is investigated,achieving a linear tuning efficiency of 42.8 pm/℃ and 55.2 pm/V,respectively.The demonstrated structure has applications for sensing and filtering in photonic integrated circuits.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12074252,12192252,and 62022058)the National Key Research and Development Program of China(No.2022YFA1205101)+1 种基金the Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01-ZX06)and the Yangyang Development Fund。
文摘Whispering-gallery-mode(WGM)microresonators can greatly enhance light-matter interaction,making them indispensable units for frequency conversion in nonlinear optics.Efficient nonlinear wave mixing in microresonators requires stringent simultaneous optical resonance and phase-matching conditions.Thus,it is challenging to achieve efficient frequency conversion over a broad bandwidth.Here,we demonstrate broadband second-harmonic generation(SHG)in the x-cut thinfilm lithium niobate(TFLN)microdisk with a quality factor above 107by applying the cyclic quasi-phase-matching(CQPM)mechanism,which is intrinsically applicable for broadband operation.Broadband SHG of continuous-wave laser with a maximum normalized conversion efficiency of~15%/m W is achieved with a bandwidth spanning over 100 nm in the telecommunication band.Furthermore,broadband SHG of femtosecond lasers,supercontinuum lasers,and amplified spontaneous emission in the telecommunication band is also experimentally observed.The work is beneficial for integrated nonlinear photonics devices like frequency converters and optical frequency comb generator based on second-order nonlinearity on the TFLN platform.
基金supported by the National Natural Science Foundation of China(Nos.12074252,12192252,62005159,62022058,61705127,and 12104289)the National Key Research and Development Program of China(No.2018YFA0306301)+2 种基金the Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01-ZX06)the Shanghai Rising-Star Program(No.20QA1405400)the Yangyang Development Fund.
文摘Optical frequency conversion based on the second-order nonlinearity(χ^((2))) only occurs in anisotropic media(or at interfaces) and thus is intrinsically polarization-dependent. But for practical applications, polarization-insensitive or independent operation is highly sought after. Here, by leveraging polarization coupling and second-order nonlinearity, we experimentally demonstrate a paradigm of TE/TM polarization-independent frequency upconversion, i.e., sum frequency generation, in the periodically poled lithium niobate-on-insulator ridge waveguide. The cascading of quasi-phase-matched polarization coupling and nonlinear frequency conversion is exploited. With a proper transverse electric field, TE and TM mode fundamental waves can be frequency-upconverted with an equal efficiency in the frequency converter. The proposed method may find ready application in all-optical wavelength conversion and upconversion detection technologies.
基金supported by the National Natural Science Foundation of China(Nos.12074252,62022058,62005159,and 11734011)National Key Research and Development Program of China(Nos.2017YFA0303701 and 2018YFA0306301)+2 种基金Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01-ZX06)Shanghai Rising-Star Program(No.20QA1405400)Shanghai Jiao Tong University(No.21X010200828)。
文摘We design and fabricate an unbalanced Mach–Zehnder interferometer(MZI)via electron beam lithography and inductively coupled plasma etching on lithium niobate thin film.The single unbalanced MZI exhibits a maximum extinction ratio of 32.4 dB and a low extra loss of 1.14 dB at the telecommunication band.Furthermore,tunability of the unbalanced MZI by harnessing the thermo-optic and electro-optic effect is investigated,achieving a linear tuning efficiency of 42.8 pm/℃ and 55.2 pm/V,respectively.The demonstrated structure has applications for sensing and filtering in photonic integrated circuits.