Fig. 1. Schematic diagram of silicon nitride sandwich waveguide structure.
Fig. 2. Mode field cross-section of silicon nitride sandwich waveguide at different wavelengths
Fig. 3. The dispersion coefficient diagram of the silicon nitride sandwich waveguide. The gray area represents the abnormal dispersion region,and the white area represents the normal dispersion region.
Fig. 4. Phase matching (PM) diagram of silicon nitride sandwich waveguide at 1550 nm input wavelength.
Fig. 5. Effect of different W on phase matching and SCG under 1 550 nm pulse,Hl=500 nm,Hs=50 nm,Hu=200 nm conditions:(a) Phase matching plots of silicon nitride sandwich waveguides under different W conditions; (b) SCG spectra of silicon nitride sandwich waveguides under different W conditions
Fig. 6. Effect of different Hl on phase matching and SCG under 1 550 nm pulse,W=1 800 nm,Hs=50 nm,Hu=200 nm conditions:(a) Phase matching plots of silicon nitride sandwich waveguides under different Hl conditions; (b) SCG spectra of silicon nitride sandwich waveguides under different Hl conditions
Fig. 7. Effect of different Hu on phase matching and SCG under 1 550 nm pulse,W=1 800 nm,Hs=50 nm,Hl=500 nm conditions: (a) Phase matching plots of silicon nitride sandwich waveguides under different Hu conditions; (b) SCG spectra of silicon nitride sandwich waveguides under different Hu conditions
Fig. 8. Effect of different Hs on phase matching and SCG under 1 550 nm pulse,W=1 800 nm,Hu=200 nm,Hl=500 nm conditions: (a) Phase matching plots of silicon nitride sandwich waveguides under different Hs conditions; (b) SCG spectra of silicon nitride sandwich waveguides under different Hs conditions
Fig. 9. SEM image of silicon nitride waveguide covered with ALD sapphire film: (a) Side view of waveguide; (b) Cross-section of waveguide
材料 | C1 | C2 | C3 | λ1 | λ2 | λ3 | Reference |
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Si | 10.668 429 33 | 0.003 043 475 | 1.541 334 08 | 0.301 516 485 5 | 1.134 751 15 | 1 104 | [15] | SiO2 | 0.696 166 3 | 0.407 942 6 | 0.897 479 4 | 0.684 043 | 0.116 241 4 | 9.896 161 | [16] | Al2O3 | 1.431 349 3 | 0.650 547 13 | 5.341 402 1 | 0.072 663 1 | 0.119 324 2 | 18.028 251 | [17] |
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Table 1. Sellmeier equation constant of refractive index of each material
Waveguide | Structure parameters/nm (w×h) | DW position/μm | SC bandwidth/μm | Reference |
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Si | 850×220 | 1.25/2.8 | 1.25~2.75 | [19] | Si3N4 | 1 100×720 | 0.7/1.8 | 0.67~2.03 | [6] | Si3N4/SiO2 | 1 000×750 | 0.7/2.1 | 0.46~2.13 | [20] | Si3N4/SiO2 | 1 300×2 700 | 0.5/4.5 | 0.5~4.5 | [21] | Si3N4/Al2O3 | 1 800×750 | 0.5/3.5 | 0.5~3.55 | This work |
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Table 2. Comparison of waveguide size, DW position and SC bandwidth in each report