Resonance Frequency of Optical Microbubble Resonators: Direct Measurements and Mitigation of Fluctuations.

This work shows the improvements in the sensing capabilities and precision of an Optical Microbubble Resonator due to the introduction of an encaging poly(methyl methacrylate) (PMMA) box. A frequency fluctuation parameter σ was defined as a score of resonance stability and was evaluated in the presence and absence of the encaging system and in the case of air- or water-filling of the cavity. Furthermore, the noise interference introduced by the peristaltic and the syringe pumping system was studied.

Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators.

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres can be thought as a store of energy with a huge variety of applications: compact laser sources, highly sensitive biochemical sensors and nonlinear phenomena. A protocol for the fabrication of both the microspheres and coupling system is given.

Confocal reflectance microscopy for determination of microbubble resonator thickness.

Optical Micro Bubble Resonators (OMBR) are emerging as new type of sensors characterized by high Q-factor and embedded micro-fluidic. Sensitivity is related to cavity field penetration and, therefore, to the resonator thickness. At the state of the art, methods for OMBR's wall thickness evaluation rely only on a theoretical approach.

Optical fiber nanotips coated with molecular beacons for DNA detection.

Optical fiber sensors, thanks to their compactness, fast response and real-time measurements, have a large impact in the fields of life science research, drug discovery and medical diagnostics. In recent years, advances in nanotechnology have resulted in the development of nanotools, capable of entering the single cell, resulting in new nanobiosensors useful for the detection of biomolecules inside living cells. In this paper, we provide an application of a nanotip coupled with molecular beacons (MBs) for the detection of DNA.

Stimulated anti-Stokes Raman scattering resonantly enhanced in silica microspheres.

Efficient stimulated anti-Stokes Raman scattering has been observed in silica microspherical resonators pumped by CW laser. This process is observed in the normal dispersion regime. The lack of correlation between stimulated anti-Stokes and Stokes scattering spectra indicates that the signal has to be resonant with the cavity.

Performance of Eudragit coated whispering gallery mode resonator-based immunosensors.

Whispering gallery mode resonators (WGMR) are an efficient tool for the realization of optical biosensors. A high Q factor preservation is a crucial requirement for good biosensor performances. In this work we present an Eudragit®L100 coated microspherical WGMR as an efficient immunosensor.

Characterization technique of optical whispering gallery mode resonators in the microwave frequency domain for optoelectronic oscillators.

Optical Q factor measurements are performed on a whispering gallery mode (WGM) disk resonator using a microwave frequency domain approach instead of using an optical domain approach. An absence of hysteretic behavior and a better linearity are obtained when performing linewidth measurements by using a microwave modulation for scanning the resonances instead of the piezoelectric-based frequency tuning capability of the laser. The WGM resonator is then used to stabilize a microwave optoelectronic oscillator.

Whispering gallery mode aptasensors for detection of blood proteins.

Whispering gallery mode resonators (WGMR), as silica microspheres, have been recently proposed as an efficient tool for the realisation of optical biosensors. In this work we present a functionalization procedure based on the DNA-aptamer sequence immobilization on WGMR, able to recognize specifically thrombin or VEGF protein, preserving a high Q factor. The protein binding was optically characterized in terms of specificity in buffer solution or in 10% diluted human serum.

Optical microspherical resonators for biomedical sensing.

Optical resonators play an ubiquitous role in modern optics. A particular class of optical resonators is constituted by spherical dielectric structures, where optical rays are total internal reflected. Due to minimal reflection losses and to potentially very low material absorption, these guided modes, known as whispering gallery modes, can confer the resonator an exceptionally high quality factor Q, leading to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown.