Heinsalu Siim, Utaka Katsuyuki
Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8050, Japan.
Sensors (Basel). 2022 May 29;22(11):4136. doi: 10.3390/s22114136.
We present two methods of improving wavelength sensitivity for multi-slot sub-wavelength Bragg grating (MS-SW BG) refractive index sensors. The sensor structure is designed to have high optical mode confinement in the gaps between the silicon pillars whereby the surrounding medium interaction is high, thus improving the sensitivity. Further sensitivity improvements are achieved by increasing the waveguide height or suspending the sensor. The second option, sensor suspension, additionally requires supporting modifications in which case various configurations are considered. After the optimization of the parameters the sensors were fabricated. For the case of a waveguide height increase to 500 nm, the sensitivity of 850 nm/RIU was obtained; for sensor suspension with fully etched holes, 922 nm/RIU; for the case of not fully etched holes, 1100 nm/RIU; with the sensor lengths of about 10 µm for all cases. These values show improvements by 16.5%, 25%, and 50.5%, respectively, compared to the previous result where the height was fixed to 340 nm.
我们提出了两种提高多槽亚波长布拉格光栅（MS-SW BG）折射率传感器波长灵敏度的方法。该传感器结构设计为在硅柱之间的间隙中具有高光学模式限制，从而与周围介质的相互作用很强，进而提高了灵敏度。通过增加波导高度或悬浮传感器可进一步提高灵敏度。第二种选择，即传感器悬浮，还需要进行支撑结构的修改，在这种情况下考虑了各种配置。在对参数进行优化之后制作了传感器。对于波导高度增加到500 nm的情况，获得了850 nm/RIU的灵敏度；对于具有完全蚀刻孔的传感器悬浮情况，为922 nm/RIU；对于未完全蚀刻孔的情况，为1100 nm/RIU；在所有情况下传感器长度约为10 µm。与之前高度固定为340 nm的结果相比，这些值分别提高了16.5%、25%和50.5%。
