Mid-Infrared Serial Microring Resonator Array for Real-Time Detection of Vapor-Phase Volatile Organic Compounds.

Area of Science:

• Photonics and Spectroscopic Sensing
• Materials Science for Optoelectronics
• Chemical Sensing Technologies

Background:

• Conventional spectrometers are often bulky and expensive.
• Volatile organic compound (VOC) detection is crucial for environmental monitoring and healthcare.
• Existing microring resonator (MR) devices typically use single-ring configurations for sensing.

Purpose of the Study:

• To develop a compact, chip-scale infrared spectrometer for VOC detection.
• To demonstrate multiwavelength mid-infrared (mid-IR) sensing using a microring resonator array (MRA).
• To enable wafer-level manufacturing and packaging of miniaturized spectrometers via CMOS processes.

Main Methods:

• Fabrication of MRAs on silicon-rich silicon nitride (SiN) thin films using CMOS processes.
• Design and optimization of microring structures using finite-difference time-domain (FDTD) modeling.
• Characterization using laser spectrum scanning and monitoring intensity variations at mid-IR absorption bands.

Main Results:

• Developed a MRA capable of multiwavelength mid-IR sensing with four spectral channels and a 100 nm free spectral range (FSR) without crosstalk.
• Demonstrated specific detection of hexane and ethanol vapor pulses by monitoring intensity variations at characteristic mid-IR absorption bands.
• Achieved discrimination among various VOC vapors through multiwavelength detection.

Conclusions:

• The mid-IR MRA is a viable component for compact spectroscopic sensing modules.
• This technology has potential applications in remote environmental monitoring and portable healthcare devices.
• CMOS-compatible wafer-level manufacturing enables scalable production of these sensors.