Plasmonic Refractive Index and Temperature Sensor Based on Graphene and LiNbO₃

Area of Science:

• Plasmonics
• Nanophotonics
• Sensor Technology

Background:

• Plasmonic perfect absorbers offer high light-matter interaction.
• Graphene and LiNbO3 are promising materials for advanced sensor applications.
• Dual-purpose sensors can enhance efficiency and reduce complexity.

Purpose of the Study:

• To investigate a dual-purpose plasmonic perfect absorber sensor.
• To evaluate its performance for refractive index and thermal sensing.
• To demonstrate a simple and efficient sensor design for fabrication.

Main Methods:

• Numerical investigation of a sensor comprising LiNbO3, graphene, gold nanorods, and a nanocavity.
• Analysis of electromagnetic energy penetration into subsurface layers.
• Testing with a functional layer for thermal sensing capabilities.

Main Results:

• Achieved 99.9% reflection for easy detection.
• Demonstrated high sensitivity of 981 nm/RIU for refractive index sensing (biomedical range).
• Obtained a figure-of-merit of 61.31 RIU⁻¹ and thermal sensitivity of -0.23 nm/°C.

Conclusions:

• The proposed sensor design is highly efficient and suitable for dual-purpose sensing.
• Simple fabrication and high performance make it promising for biomedical and thermal monitoring.
• The sensor shows excellent potential for practical applications requiring high sensitivity and detection.