Vernier Effect-Enhanced Temperature Sensing Based on On-Chip Spiral Resonant Cavities

Area of Science:

• Photonics and Optical Sensing
• Integrated Optics
• Nanotechnology

Background:

• The optical Vernier effect enhances optical sensor sensitivity and resolution.
• On-chip waveguide resonant cavities face limitations in cavity length and free spectral range.
• Existing Vernier effect detection systems struggle with large envelope periods.

Purpose of the Study:

• To propose a novel on-chip waveguide structure to optimize the detection range of the cascaded Vernier effect.
• To overcome space limitations in on-chip resonant cavities.
• To enhance the sensitivity and range of optical sensing technologies.

Main Methods:

• Designed a spiral resonant cavity to extend effective cavity length within a limited area.
• Utilized whispering gallery modes in on-chip optical waveguide resonant cavities.
• Connected two similar-length resonant cavities in series to leverage the Vernier effect.

Main Results:

• The spiral cavity achieved a length of 7.50 m, significantly increasing the effective cavity length.
• The envelope free spectral width was reduced to 371.29 MHz, facilitating easier detection.
• Temperature sensing demonstrated a 14.19-fold increase in sensitivity compared to a single resonant cavity.

Conclusions:

• The proposed spiral resonant cavity structure effectively optimizes the detection range of the cascaded Vernier effect.
• This approach significantly enhances the sensitivity of on-chip optical sensors.
• The study offers a new pathway for developing wide-range, high-sensitivity Vernier sensing technologies.