Lithium niobate has received interest in nonlinear frequency conversion due to its wide transparency window,from ultraviolet to mid-infrared spectral regions,and large second-order nonlinear susceptibility.However,its...Lithium niobate has received interest in nonlinear frequency conversion due to its wide transparency window,from ultraviolet to mid-infrared spectral regions,and large second-order nonlinear susceptibility.However,its nanostructure is generally difficult to etch,resulting in low-Q resonance and lossy nanostructures for second harmonic generation.By applying the concept of bound states in the continuum,we performed theoretical and experimental investigations on high-Q resonant etchless thin-film lithium niobate with Si O_(2) nanostructures on top for highly efficient second harmonic generation.In the fabricated nanostructured devices,a resonance with a Q factor of 980 leads to the strong enhancement of second harmonic generation by over 1500 times compared with that in unpatterned lithium niobate thin film.Although the pump slightly deviates from central resonance,an absolute conversion efficiency of 6.87×10^(-7) can be achieved with the fundamental pump peak intensity of 44.65 MW/cm^(2),thus contributing to the normalized conversion efficiency of 1.54×10^(-5)cm^(2)/GW.Our work establishes an etchless lithium niobate device for various applications,such as integrated nonlinear nanophotonics,terahertz frequency generation,and quantum information processing.展开更多
Recently, nonlinear photonics has attracted considerable interest. Among the nonlinear effects, second harmonic generation(SHG) remains a hot research topic. The recent development of thin film lithium niobate(TFLN) t...Recently, nonlinear photonics has attracted considerable interest. Among the nonlinear effects, second harmonic generation(SHG) remains a hot research topic. The recent development of thin film lithium niobate(TFLN) technology has superior performances to the conventional counterparts. Herein, this review article reveals the recent progress of SHG based on TFLN and its integrated photonics. We mainly discuss and compare the different techniques of TFLN-based structures to boost the nonlinear performances assisted by localizing light in nanostructures and structured waveguides.Moreover, our conclusions and perspectives indicate that more efficient methods need to be further explored for higher SHG conversion efficiency on the TFLN platform.展开更多
An all-optical light–control–light functionality with the structure of a microfiber knot resonator (MKR) coated with tin disulfide (SnS_2) nanosheets is experimentally demonstrated. The evanescent light in the MKR [...An all-optical light–control–light functionality with the structure of a microfiber knot resonator (MKR) coated with tin disulfide (SnS_2) nanosheets is experimentally demonstrated. The evanescent light in the MKR [with a resonance Q of ～59,000 and an extinction ratio (ER) of ～26 dB] is exploited to enhance light–matter interaction by coating a two-dimensional material SnS_2 nanosheet onto it. Thanks to the enhanced light–matter interaction and the strong absorption property of SnS_2, the transmitted optical power can be tuned quasi-linearly with an external violet pump light power, where a transmitted optical power variation rate ΔT with respect to the violet light power of ～0.22 dB∕mW is obtained. In addition, the MKR structure possessing multiple resonances enables a direct experimental demonstration of the relationship between resonance properties (such as Q and ER), and the obtained ΔT variation rate with respect to the violet light power. It verifies experimentally that a higher resonance Q and a larger ER can lead to a higher ΔT variation rate. In terms of the operating speed, this device runs as fast as ～3.2 ms. This kind of all-optical light–control–light functional structure may find applications in future all-optical circuitry, handheld fiber sensors, etc.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 61775084, and 62075088)the National Safety Academic Fund (Grant No. U2030103)+2 种基金the Natural Science Foundation of Guangdong Province (Grant Nos. 2020A1515010791, and 2021A0505030036)the Open Fund of Guangdong Provincial Key Laboratory of Information Photonics Technology of Guangdong University of Technology (Grant No. GKPT20-03)the Fundamental Research Funds for the Central Universities (Grant Nos. 21622107, and 21622403)。
文摘Lithium niobate has received interest in nonlinear frequency conversion due to its wide transparency window,from ultraviolet to mid-infrared spectral regions,and large second-order nonlinear susceptibility.However,its nanostructure is generally difficult to etch,resulting in low-Q resonance and lossy nanostructures for second harmonic generation.By applying the concept of bound states in the continuum,we performed theoretical and experimental investigations on high-Q resonant etchless thin-film lithium niobate with Si O_(2) nanostructures on top for highly efficient second harmonic generation.In the fabricated nanostructured devices,a resonance with a Q factor of 980 leads to the strong enhancement of second harmonic generation by over 1500 times compared with that in unpatterned lithium niobate thin film.Although the pump slightly deviates from central resonance,an absolute conversion efficiency of 6.87×10^(-7) can be achieved with the fundamental pump peak intensity of 44.65 MW/cm^(2),thus contributing to the normalized conversion efficiency of 1.54×10^(-5)cm^(2)/GW.Our work establishes an etchless lithium niobate device for various applications,such as integrated nonlinear nanophotonics,terahertz frequency generation,and quantum information processing.
基金supported by the National Natural Science Foundation of China(Nos.61775084,61705089,61705087,62075088,and 61505069)NSAF(No.U2030103)+3 种基金Guangdong Special Support Program(No.2016TQ03X962)Natural Science Foundation of Guangdong Province(Nos.2021A0505030036,2020A151501791,and 2021A1515011875)Open Fund of Guangdong Provincial Key Laboratory of Information PhotonicsTechnologyofGuangdongUniversityof Technology(No.GKPT20-03)Fundamental Research Funds for the Central Universities(No.11620444)。
文摘Recently, nonlinear photonics has attracted considerable interest. Among the nonlinear effects, second harmonic generation(SHG) remains a hot research topic. The recent development of thin film lithium niobate(TFLN) technology has superior performances to the conventional counterparts. Herein, this review article reveals the recent progress of SHG based on TFLN and its integrated photonics. We mainly discuss and compare the different techniques of TFLN-based structures to boost the nonlinear performances assisted by localizing light in nanostructures and structured waveguides.Moreover, our conclusions and perspectives indicate that more efficient methods need to be further explored for higher SHG conversion efficiency on the TFLN platform.
基金National Natural Science Foundation of China (NSFC) (61475066,61505069,61675092,61705087,61705089,61775084)Guangdong Special Support Program (2016TQ03X962)+3 种基金Natural Science Foundation of Guangdong Province (2015A030306046,2016A030310098,2016A030311019)Science and Technology Project of Guangzhou (201605030002,201607010134,201704030105)Science and Technology Projects of Guangdong Province (2014B090905001)Rail Transit Healthy Operation Cooperative Innovation Center of Zhuhai (55560307)
文摘An all-optical light–control–light functionality with the structure of a microfiber knot resonator (MKR) coated with tin disulfide (SnS_2) nanosheets is experimentally demonstrated. The evanescent light in the MKR [with a resonance Q of ～59,000 and an extinction ratio (ER) of ～26 dB] is exploited to enhance light–matter interaction by coating a two-dimensional material SnS_2 nanosheet onto it. Thanks to the enhanced light–matter interaction and the strong absorption property of SnS_2, the transmitted optical power can be tuned quasi-linearly with an external violet pump light power, where a transmitted optical power variation rate ΔT with respect to the violet light power of ～0.22 dB∕mW is obtained. In addition, the MKR structure possessing multiple resonances enables a direct experimental demonstration of the relationship between resonance properties (such as Q and ER), and the obtained ΔT variation rate with respect to the violet light power. It verifies experimentally that a higher resonance Q and a larger ER can lead to a higher ΔT variation rate. In terms of the operating speed, this device runs as fast as ～3.2 ms. This kind of all-optical light–control–light functional structure may find applications in future all-optical circuitry, handheld fiber sensors, etc.
