Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input

Area of Science:

• Photonics
• Optical Sensing
• Microresonator Technology

Background:

• Optical microresonators are valuable for sensing applications.
• Sensing mechanisms include dispersive (resonance frequency shift) and dissipative (analyte absorption affecting mode linewidth and dip depth).
• Achieving high dip-depth sensitivity often requires challenging overcoupling conditions.

Purpose of the Study:

• To experimentally validate theoretical predictions of enhanced sensitivity using multimode input in optical microresonators.
• To demonstrate a significant increase in dip-depth sensitivity compared to single-mode input and linewidth sensitivity.
• To explore the practical application of multimode excitation for improved sensing.

Main Methods:

• Theoretical modeling of multimode input effects on microresonator sensitivity.
• Experimental setup utilizing a hollow bottle resonator with an absorbing dye in methanol.
• Fabrication and characterization of an asymmetrically tapered fiber for generating multimode input.
• Measurement and analysis of resonance shifts, linewidth changes, and dip depth variations.

Main Results:

• Experimental confirmation of theoretically predicted sensitivity enhancements.
• Achieved a sensitivity enhancement of several thousand times for dip depth with multimode input compared to single-mode input.
• Observed a nearly 100-fold enhancement in dip-depth sensitivity over linewidth sensitivity.
• Results align with theoretical predictions for multimode-enhanced dissipative sensing.

Conclusions:

• Multimode input is a highly effective strategy for dramatically enhancing the sensitivity of optical microresonator-based sensors.
• This approach offers a significant advantage over conventional single-mode excitation, particularly for dissipative sensing mechanisms.
• The demonstrated technique provides a practical pathway to achieving ultra-sensitive optical detection.