Simultaneous measurement of quality factor and wavelength shift by phase shift microcavity ring down spectroscopy

Area of Science:

• Optics and Photonics
• Biotechnology and Biosensing
• Physical Chemistry

Background:

• Optical resonant microcavities are crucial for high-sensitivity biosensing applications.
• Traditional detection relies on resonant wavelength shifts, susceptible to laser intensity noise.
• Alternative detection methods are needed to improve biosensor robustness and accuracy.

Purpose of the Study:

• To investigate the application of phase shift cavity ring down spectroscopy (PSCRDS) for microcavity biosensing.
• To demonstrate simultaneous measurement of optical cavity quality factor (Q-factor) and resonant wavelength shift.
• To assess the performance of PSCRDS in liquid-phase biosensing during kinetic measurements.

Main Methods:

• Utilized biotinylated microtoroid resonant cavities for biosensing experiments.
• Employed phase shift cavity ring down spectroscopy (PSCRDS) for simultaneous Q-factor and wavelength shift measurements.
• Conducted measurements during the dissociation phase of biotin-streptavidin interactions in a liquid environment.

Main Results:

• Successfully demonstrated simultaneous measurement of Q-factor and wavelength shift using PSCRDS on microcavities.
• Obtained dissociation curves for biotin-streptavidin reaction that align with previously published data.
• Validated the robustness of PSCRDS against laser intensity fluctuations in liquid-phase measurements.

Conclusions:

• Phase shift cavity ring down spectroscopy is a viable technique for liquid-phase microcavity biosensing.
• PSCRDS enables simultaneous monitoring of Q-factor and wavelength shift, enhancing detection capabilities.
• This method provides accurate kinetic measurements for biosensor applications, overcoming limitations of traditional techniques.