• Chinese Optics Letters
  • Vol. 22, Issue 3, 033602 (2024)
Rui Ge1, Jiangwei Wu1, Xiangmin Liu1, Yuping Chen1,2,*, and Xianfeng Chen1,3,4
Author Affiliations
  • 1State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
  • 2School of Physics, Ningxia University, Yinchuan 750021, China
  • 3Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
  • 4Collaborative Innovation Center of Light Manipulations and Applications, Shandong Normal University, Jinan 250358, China
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    DOI: 10.3788/COL202422.033602 Cite this Article Set citation alerts
    Rui Ge, Jiangwei Wu, Xiangmin Liu, Yuping Chen, Xianfeng Chen, "Recent progress in thin-film lithium niobate photonic crystal [Invited]," Chin. Opt. Lett. 22, 033602 (2024) Copy Citation Text show less
    Schematic of integrated LNPhC devices, including wavelength converter, sensor, modulator, opto-mechanical cavity, and superprism.
    Fig. 1. Schematic of integrated LNPhC devices, including wavelength converter, sensor, modulator, opto-mechanical cavity, and superprism.
    Schematic of (a) TF-LNPhC on silica. Adapted with permission from [20]. (b) Suspended LNPhC. Adapted with permission from [22]. (c) APE LNPhC on common LN with lateral confinement. Adapted with permission from [15].
    Fig. 2. Schematic of (a) TF-LNPhC on silica. Adapted with permission from [20]. (b) Suspended LNPhC. Adapted with permission from [22]. (c) APE LNPhC on common LN with lateral confinement. Adapted with permission from [15].
    Schematic of the LNPhC fabricated by EBL with Ar+ etching. (a) 2D LNPhC cavity. Adapted with permission from [28]. (b) LNPhC cavity with ultra-high Q-factor. Adapted with permission from [29]. (c) LNPhC modulator. Adapted with permission from [30].
    Fig. 3. Schematic of the LNPhC fabricated by EBL with Ar+ etching. (a) 2D LNPhC cavity. Adapted with permission from [28]. (b) LNPhC cavity with ultra-high Q-factor. Adapted with permission from [29]. (c) LNPhC modulator. Adapted with permission from [30].
    (a) Fabrication procedures of LNPhC based on the reactive ion etching and the IBEE technique. Adapted with permission from [10] and [25]. (b) Fabrication procedure of LNPhC based on redeposition-free FIB technique. Adapted with permission from [42]. (c) SEM image of holes fabricated by IBEE technique and redeposition-free FIB technique. Adapted with permission from [10] and [42].
    Fig. 4. (a) Fabrication procedures of LNPhC based on the reactive ion etching and the IBEE technique. Adapted with permission from [10] and [25]. (b) Fabrication procedure of LNPhC based on redeposition-free FIB technique. Adapted with permission from [42]. (c) SEM image of holes fabricated by IBEE technique and redeposition-free FIB technique. Adapted with permission from [10] and [42].
    (a) Schematic and (b) SEM image of the etchless LNPhC with silica as the mask. Adapted with permission from [43]. (c) Schematic and (d) SEM image of the etchless LNPhC with polymer as the mask. Adapted with permission from [44].
    Fig. 5. (a) Schematic and (b) SEM image of the etchless LNPhC with silica as the mask. Adapted with permission from [43]. (c) Schematic and (d) SEM image of the etchless LNPhC with polymer as the mask. Adapted with permission from [44].
    (a) Schematic of tapered fiber coupling. Adapted with permission from [28]. (b) End-face coupling. Adapted with permission from [15]. (c) Cross-polarized resonant scattering coupling. Adapted with permission from [38]. (d) Grating coupling. Adapted with permission from [34].
    Fig. 6. (a) Schematic of tapered fiber coupling. Adapted with permission from [28]. (b) End-face coupling. Adapted with permission from [15]. (c) Cross-polarized resonant scattering coupling. Adapted with permission from [38]. (d) Grating coupling. Adapted with permission from [34].
    (a), (b) Optical microscopy images of two different mode-gap cavities. (c) Spectrum of the second-harmonic signal of the mode-gap cavity. (d) Second-harmonic power as a function of the fundamental pump wave power of the mode-gap cavity. Adapted with permission from [28]. (e) Second-harmonic power as a function of the fundamental pump wave power of the L3 cavity. Adapted with permission from [38]. (f) Second-harmonic power as a function of the fundamental pump wave of the bulk cavity made by redeposition-free FIB. Adapted with permission from [42].
    Fig. 7. (a), (b) Optical microscopy images of two different mode-gap cavities. (c) Spectrum of the second-harmonic signal of the mode-gap cavity. (d) Second-harmonic power as a function of the fundamental pump wave power of the mode-gap cavity. Adapted with permission from [28]. (e) Second-harmonic power as a function of the fundamental pump wave power of the L3 cavity. Adapted with permission from [38]. (f) Second-harmonic power as a function of the fundamental pump wave of the bulk cavity made by redeposition-free FIB. Adapted with permission from [42].
    (a) Schematic of the LNPhC waveguide used for generating spectrally unentangled biphoton states. Mode profiles of pump, signal, and idler modes at the (b) z = 0 and (c) y = 0 planes. (d) Band diagram of the pump mode. (e) Band diagram of the signal and idler modes. (f) Bloch harmonic distribution of the modes. Adapted with permission from [68].
    Fig. 8. (a) Schematic of the LNPhC waveguide used for generating spectrally unentangled biphoton states. Mode profiles of pump, signal, and idler modes at the (b) z = 0 and (c) y = 0 planes. (d) Band diagram of the pump mode. (e) Band diagram of the signal and idler modes. (f) Bloch harmonic distribution of the modes. Adapted with permission from [68].
    (a) SEM image, (b) experimental setup, and (c) results for Fano resonance-based LNPhC sensor. Adapted with permission from [75]. (d) Simulated transmission of the BIC LNPhC sensor. Adapted with permission from [80].
    Fig. 9. (a) SEM image, (b) experimental setup, and (c) results for Fano resonance-based LNPhC sensor. Adapted with permission from [75]. (d) Simulated transmission of the BIC LNPhC sensor. Adapted with permission from [80].
    (a) Structure and (b) SEM image and enlarged SEM image of the mode-gap LNPhC modulator. (c) Eye diagrams of the electro-optic switch. Adapted with permission from [30].
    Fig. 10. (a) Structure and (b) SEM image and enlarged SEM image of the mode-gap LNPhC modulator. (c) Eye diagrams of the electro-optic switch. Adapted with permission from [30].
    (a) SEM image of suspended LNPhC nanobeam and (b) observed mechanical lasing. Adapted with permission from [31]. (c) SEM image of the LNPhC transducer. Adapted with permission from [33]. (d) Transmission spectrum and power spectral density change for the mechanical mode. Adapted with permission from [54].
    Fig. 11. (a) SEM image of suspended LNPhC nanobeam and (b) observed mechanical lasing. Adapted with permission from [31]. (c) SEM image of the LNPhC transducer. Adapted with permission from [33]. (d) Transmission spectrum and power spectral density change for the mechanical mode. Adapted with permission from [54].
    Ref.Cavity TypeQ-factorFabrication MethodYear
    [38]L3775 (Sim.), 535 (Exp.)IBEE2013
    [52]Mode-gap3.9 × 106 (Sim.)2015
    [21]Mode-gap330 (Sim.), 156 (Exp.)FIB2016
    [27]Mode-gap6 × 106 (Sim.), 1.09 × 105 (Exp.)EBL + Ar+ etching2017
    [53]Mode-gap5.43 × 104 (Exp.)EBL + Ar+ etching2018
    [28]Mode-gap1.5 × 106 (Sim.), 3.51 × 105 (Exp.)EBL + Ar+ etching2019
    [29]Mode-gap1.23 × 108 (Sim.), 1.41 × 106 (Exp.)EBL + Ar+ etching2019
    [31]Mode-gap4 × 106 (Sim.), 3.5 × 105 (Exp.)EBL + Ar+ etching2019
    [51]L4/3 with inverse design9.7 × 106 (Sim.)2020
    [54]Mode-gap6.29 × 104 (Exp.)EBL + Ar+ etching2020
    [30]Mode-gap1.34 × 105 (Exp.)EBL + Ar+ etching2020
    [32]Mode-gap1.7 × 104 (Exp.)EBL + Ar+ etching2020
    [33]Mode-gap4.7 × 105 (Exp.)EBL + Ar+ etching2020
    [42]Bulk75 (Exp.)Redeposition-free FIB2022
    [44]BIC12,010 (Exp.)Etchless LNPhC2022
    [34]Mode-gap1.58 × 105 (Exp.)EBL + Ar+ etching2023
    Table 1. Q-Factors of the Recent Works Based on the TF-LNPhC Cavity
    Ref.Modulator StructureVπ · L (V · cm)Vπ (V)L (mm)3 dB Bandwidth (GHz)Sim./Exp.Year
    [87]MZI0.66100Sim.2013
    [84]Slow light waveguide0.006311.80.00531Exp.2014
    [30]Nanobeam17.5Exp.2020
    [44]Etchless waveguide28Exp.2022
    [85]Nanobeam0.0874100.0874600Sim.2022
    [86]Nanobeam1.4280Sim.2023
    Table 2. Performance Parameters of the Modulator Based on the TF-LNPhCa
    Ref.Q-factor (Optical)Q-factor (Mechanical)Coupling RateYear
    [27]1 × 105619271 kHz2017
    [31]3 × 10517,000120 kHz2019
    [54]6.3 × 104652020
    [32]1.7 × 104202020
    Table 3. Optomechanic Properties of the LNPhC Nanobeam for Some State-of-the-Art Experimental Works
    MethodSidewall Angle (°)Etching Technique of HolesFabrication Scale
    FIBNear 83Ga+ millingSmall scale
    EBL + Ar+ plasma etching55–85Ar+ millingWafer scale
    Redeposition-free FIBNear 90Ga+ millingSmall scale
    IBEE90HF wet etchingWafer scale
    Table 4. Comparison of Different Fabrication Processes of TF-LNPhC
    Rui Ge, Jiangwei Wu, Xiangmin Liu, Yuping Chen, Xianfeng Chen, "Recent progress in thin-film lithium niobate photonic crystal [Invited]," Chin. Opt. Lett. 22, 033602 (2024)
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