The performance of on-chip gas sensors based on light absorption is mainly determined by the light–gas interaction. In this paper, slow-light Bloch slot waveguides (BSW) are proposed to improve sensing performance. The sensing performance is enhanced in two mechanisms. On the one hand, light is confined in the slot to increase the overlap of the mode field and the gas; on the other hand, the slow-light effect is achieved by adjusting the subwavelength grating period to increase the group index. By joint engineering the evanescent fields and group index, for a low pump power of 10 mW and a propagation loss of 3 dB/cm, the detection limit of 0.034 ppm in the near-infrared and the detection limit of 0.29 ppm in the mid-infrared at the optimum propagation length of 1.45 cm are obtained, respectively. The proposed BSW provides a promising platform for high-performance gas sensing.

中文翻译：

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片上气体传感慢光Bloch缝隙波导的设计与分析

基于光吸收的片上气体传感器的性能主要取决于光气相互作用。本文提出了慢光布洛赫缝隙波导（BSW），以提高传感性能。通过两种机制增强了感测性能。一方面，光被限制在缝隙中以增加模场和气体的重叠；另一方面，光被限制在缝隙中。另一方面，通过调节亚波长光栅周期以增加组指数来实现慢光效果。通过联合设计渐逝场和组指数，对于10 mW的低泵浦功率和3 dB / cm的传输损耗，近红外的检出限为0.034 ppm，中红外的检出限为0.29 ppm。分别获得最佳传播长度为1.45厘米的红外光。