Fabrication of high-aspect-ratio α-Si pillar photonic crystalcoupled plasmonic waveguide for on-chip gas sensing

This paper presents the nanofabrication of a photonic crystal waveguide made on a plasmonic integrated photonics platform for on-chip gas sensing applications. A complex fabrication procedure involving 5 different electron-beam lithography (EBL) steps followed by lift-off and inductively coupled plasma-reactive ion etching (ICP-RIE) processes are successfully developed to realize almost smooth-surface and high-aspect-ratio big area nano-pillars. Preliminary optical test results measured on fabricated hybrid plasmonic-photonic crystal waveguides prove the device concept and the fabrication’s success.
Non-dispersive infrared (NDIR) spectroscopy is the most widely used spectroscopic method to detect chemicals and gas in the ambient. In recent years, miniaturizing NDIR sensors has attracted considerable industrial interest in addressing the high market demand for portable devices and multifunctional sensors for the internet of things. Many device structures and concepts have been proposed including integrated plasmonic emitters and sensors, and integrated photonic waveguides utilizing evanescent field sensing with integrated detectors and sensors. In our previous works, we proposed an efficient miniaturized sensing concept utilizing a hybrid plasmonic-photonic waveguide platform