A whispering-gallery scanning microprobe for Raman spectroscopy and imaging

Area of Science:

• Optics
• Nanotechnology
• Spectroscopy

Background:

• Optical whispering-gallery-mode microsensors offer potential for various sensing applications.
• Existing micro/nanosensors struggle to achieve both high sensitivity and large detection areas simultaneously.
• These limitations hinder widespread adoption in fields like biomedical monitoring and material characterization.

Purpose of the Study:

• To develop a novel scanning whispering-gallery-mode microprobe.
• To overcome the trade-off between sensitivity and detection area in micro/nanosensors.
• To demonstrate enhanced Raman spectroscopy with improved molecular detection and imaging capabilities.

Main Methods:

• Integration of whispering-gallery modes with nanoplasmonics in a scanning microprobe design.
• Utilizing the microprobe for enhanced Raman spectroscopy.
• Performing two-dimensional micron-resolution Raman imaging of molecular distribution.

Main Results:

• The microprobe achieved a two-orders-of-magnitude sensitivity improvement over traditional plasmonics-only enhancement.
• Demonstrated molecular detection with stronger signals and lower optical power requirements compared to surface-enhanced-Raman-spectroscopy substrates.
• Successfully realized two-dimensional micron-resolution Raman imaging, expanding the effective detection area.

Conclusions:

• The developed scanning microprobe successfully combines ultrahigh sensitivity and a large detection area.
• This novel configuration significantly enhances Raman spectroscopy for molecular fingerprinting.
• The versatile microprobe is beneficial for material characterization, chemical imaging, and quantum-enhanced sensing.