Hole geometry effect on stop-band characteristics of photonic crystal in Ti-diffused LiNbO^sub 3^ waveguide
Effects of finite hole depth and non-cylindrical hole shape on stop-band characteristics of photonic crystal formed by air-hole square lattice in Ti-diffused LiNbO3 strip waveguide were studied theoretically. The study shows that hole depth determines the contrast of stop-band, and the hole radius a...
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Veröffentlicht in: | Materials chemistry and physics 2017-01, Vol.186, p.498 |
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Sprache: | eng |
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Zusammenfassung: | Effects of finite hole depth and non-cylindrical hole shape on stop-band characteristics of photonic crystal formed by air-hole square lattice in Ti-diffused LiNbO3 strip waveguide were studied theoretically. The study shows that hole depth determines the contrast of stop-band, and the hole radius and conical angle determine the bandgap and location. Cylindrical holes must be sufficiently deep so as to overlap most of waveguide mode and hence obtain a stop-band with high contrast, sharp edge and broad bandgap. Non-cylindrical holes seriously affect the stop-band features. Conical holes cause low contrast and narrow bandgap, and the stop-band shifts with the conical angle. For the cylindrical-conical hybrid holes, the cylindrical portion determines the desired features. Given the difficulty in fabricating high aspect-ratio cylindrical holes, we propose to fabricate the holes at the bottom of a shallow trench, which is introduced into waveguide surface prior to the hole milling. |
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ISSN: | 0254-0584 1879-3312 |