Laser diagnostics for droplet characterization: Application of morphology dependent resonances

Whispering gallery modes in bottle microresonators

“…Modes with very large q-number show very rapid oscillation of fields around the center of the bottle in the axial direction [9] and therefore are not excited as the field overlap averages to zero. The breaking of degeneracy due to ellipticity results in very dense spectra similar to deformed microspheres [10,15]. The apparent differences in modal density shown in the transmission spectra as the tapered fiber is moved from the bottle centre to the neck is primarily due to differences in modal excitation and selectivity and not inherent modal density changes.…”

“…(azimuthal), p (radial) and q (axial) [8,9] and a corresponding characteristic wavelength λ mpq . Due to the strong asphericity of the bottle resonator, all the supported modes are degenerate with strongly overlapping FSRs and very large mode density [10,15]. The wavelength selectivity and the strength of evanescent excitation of the resonator will depend upon the degree of phase-matching and spatial overlap between the tapered-fiber field and the resonator mode fields at the different positions of the tapered fiber.…”

Microtaper fiber excitation effects in bottle microresonators

“…BMR WGMs are defined by m (azimuthal), ρ (radial) and q (axial) mode numbers and characteristic wavelength λ mρq . In contrast with near-perfect-microspheres, azimuthal mode degeneracy is broken in BMRs and the strong overlap of different mode families' result in very dense and complex transmission spectra [10][11][12] .…”

“…We have previously demonstrated a simple and versatile way of fabricating BMRs through "soften-and-compress" technique 10 . As a result of strong asphericity of the BMR, dense and complex resonance spectral feature were generated due to degenerate supported modes with strongly overlapping FSRs and very large mode density 11,12 . Although the dense spectral features could be greatly beneficial for CQED studies, it would be a major drawback should the BMR is to be utilized for sensing purposes.…”

Vibrating Orifice Droplet Generator for Studying Fast Processes Associated with Microdroplets

“…Chang and his coworkers have determined droplet size and species concentration (Serpengiizel et al, 1990), droplet temperature (Chen et al, 1996), and droplet deformations (Chen et al, 1992) from resonances observed in light scattered inelastically by droplets generated from a VOAG. Swindal et al (1996) used the approximate ~eriodicitv relations for resonances observed in lasing spectra to estimate the evaporation rates of segmented streams of Rhodamine 6G doped ethanol droplets generated by a VOAG. From the results on different configurations of droplets they indicated that the evaporation rate is affected by interparticle interactions.…”