Broadband-Tunable Vanadium Dioxide (VO₂)-Based Linear Optical Cavity Sensor.

Area of Science:

• Photonics and Optical Sensing
• Materials Science
• Nanotechnology

Background:

• Silicon-on-insulator (SOI) platforms offer advantages in miniaturization and power efficiency for optical sensors.
• Existing sensors face limitations in detecting complex mixtures and require specific wavelength reflectors.
• Vanadium dioxide (VO2) exhibits phase-change properties, enabling tunable optical responses.

Purpose of the Study:

• To propose and investigate a broadband, thermally tunable optical sensor model based on vanadium dioxide (VO2).
• To address limitations of current sensors, including size, power consumption, and ternary mixture detection.
• To leverage the Fabry-Pérot (FP) effect for enhanced sensing capabilities.

Main Methods:

• Utilized a finite element method to model a linear optical cavity sensor.
• Integrated a silicon wire waveguide on an SOI platform with VO2 phase-change materials.
• Simulated optical transmission modulation and sensitivity across a broad spectral region (125-230 THz).

Main Results:

• Achieved a smooth transmission modulation range of 0.8 (insulator) and 0.03 (conductive) for VO2.
• Demonstrated a high sensitivity of 20.2 THz/RIU (179.56 nm/RIU) with a 3.84 μm cavity length.
• Observed a change in resonating mode line width (Δν) of 6.94 THz/RIU (59.96 nm/RIU) with changes in the imaginary part of the refractive index (k).

Conclusions:

• The proposed VO2-based SOI optical sensor exhibits significantly higher sensitivity than existing technologies.
• The sensor's ability to detect changes in the imaginary refractive index enables ternary mixture sensing without chemical modification.
• Potential applications include chemical industries, environmental monitoring, and biomedical sensing.