A novel, to the best of our knowledge, mid-infrared chalcogenide (ChG) on magnesium fluoride (${{\rm MgF} _{2}}$) waveguide gas sensor was fabricated by using the lift-off method. ${{\rm MgF} _{2}}$ was used as a lower cladding layer to increase the external confinement factor for enhancing light–gas interaction. Wavelength modulation spectroscopy (WMS) was used in carbon dioxide (${{\rm CO} _{2}}$) detection at the wavelength of 4319 nm (${2315.2}\;{{\rm cm}^{- 1}}$). The limit of detection for the 1-cm-long sensing waveguide based on WMS is ${\sim} {0.3}\%$, which is ${\gt} {8}$ times lower than the same sensor using direct absorption spectroscopy (DAS). The combination of WMS with the waveguide gas sensor provides a new measurement scheme for the performance improvement of on-chip gas detection.

中文翻译：

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基于波长调制光谱的中红外 ChG-on-MgF2 波导气体传感器

据我们所知，一种新颖的中红外硫族化物（ChG）在氟化镁（${{\rm MgF} _{2}}$）波导气体传感器上是通过使用剥离方法制造的。${{\rm MgF} _{2}}$被用作较低的包层以增加外部限制因子以增强光-气相互作用。波长调制光谱 (WMS) 用于二氧化碳 ( ${{\rm CO} _{2}}$ ) 检测，波长为 4319 nm ( ${2315.2}\;{{\rm cm}^{- 1 }}$）。基于 WMS 的 1 cm 长传感波导的检测限为${\sim} {0.3}\%$，即${\gt} {8}$比使用直接吸收光谱 (DAS) 的相同传感器低几倍。WMS与波导气体传感器的结合为片上气体检测的性能提升提供了一种新的测量方案。