Diamonds Are a Spectroscopist鈥檚 Best Friend: Thin-Film Diamond Mid-Infrared Waveguides for Advanced Chemical Sensors/Biosensors

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• 作者：Xiaofeng Wang ; Mikael Karlsson ; Pontus Forsberg ; Markus Sieger ; Fredrik Nikolajeff ; Lars 脰sterlund ; Boris Mizaikoff
• 刊名：Analytical Chemistry
• 出版年：2014
• 出版时间：August 19, 2014
• 年：2014
• 卷：86
• 期：16
• 页码：8136-8141
• 全文大小：292K
• ISSN：1520-6882

文摘

The first combination of mid-infrared (MIR) tunable quantum cascade lasers (tQCLs) with thin-film diamond strip waveguides (DSWGs) suitable for advanced chemical sensing/biosensing is demonstrated. The sensing system is composed of thin diamond films grown on surface-passivated Si wafers via chemical vapor deposition (CVD) and microstructured using inductively coupled plasma (ICP) etching, serving as photonic waveguides for radiation emitted by a broadly tunable quantum cascade laser (tQCL) in the spectral regime of 5.78鈥?.35 渭m (1570鈥?730 cm^鈥?). The characterization of the free-standing diamond waveguides reveals excellent transmission properties across a broad MIR band. As a proof of concept, the detection of acetone in D₂O via evanescent field absorption is demonstrated achieving a limit of detection (LOD) as low as 200 pL, which indicates a significant sensitivity improvement compared to conventional MIR slab/strip waveguides reported to date. Providing characteristic absorption features within the tuning range of the tQCL, studies using anisaldehyde as an analyte further corroborate the potential of tQCL-DSWG-based chemical sensors/biosensors.