Slow-light enhanced subwavelength plasmonic waveguide refractive index sensors

Area of Science:

• Photonics and Nanophotonics
• Optical Sensing Technologies

Background:

• Subwavelength scale refractive index sensors are crucial for various applications.
• Metal-dielectric-metal (MDM) waveguides offer potential for miniaturized optical devices.
• Slow-light phenomena can enhance light-matter interactions.

Purpose of the Study:

• To introduce and analyze slow-light enhanced subwavelength scale refractive index sensors.
• To compare the performance of slow-light based sensors with conventional MDM waveguide sensors.
• To investigate the impact of group velocity reduction on sensor sensitivity and required sensing length.

Main Methods:

• Utilizing plasmonic metal-dielectric-metal (MDM) waveguide structures.
• Designing slow-light systems using stub and double-stub resonators coupled to MDM waveguides.
• Systematically analyzing the sensing characteristics, including effective index sensitivity and reflection/transmission coefficients.
• Comparing performance metrics against a reference MDM waveguide with a small width structure.

Main Results:

• Slow-light enhanced sensors exhibit significantly increased sensitivity to refractive index variations.
• Reduced group velocity in slow-light systems leads to enhanced sensitivity of waveguide modes.
• The proposed slow-light sensors demonstrate 3.9x and 3.5x improvements in refractive index sensitivity.
• A reduction in the required sensing length by 2x and 3x was achieved compared to the reference sensor.

Conclusions:

• Slow-light engineering in plasmonic MDM waveguides provides a powerful approach for enhanced refractive index sensing.
• These enhanced sensors offer superior performance in terms of sensitivity and length efficiency.
• The findings pave the way for more compact and sensitive optical sensing devices.