Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Optics Letters

Q switching by saturable absorption in microdroplets: elastic scattering and laser emission

Jürgen Popp, Mitchell H. Fields, Richard K. Chang

Published Sep 1, 1997• 25 citations
Publisher

Abstract

Laser-induced modification of cavity Q's has been achieved in a microdroplet containing a saturable absorber. The elastic-scattering spectra from such droplets for higher incident intensities show that cavity Q's are increased when the absorption is bleached. The lasing spectra from a droplet containing a saturable absorber and laser dye are modified when an intense bleaching field is injected into the droplet cavity after the pump field has initiated the lasing.

DOI
10.1364/ol.22.001296

Related papers

Cavity-enhanced emission in microdroplets

A. J. Campillo, J. D. Eversole, H.‐B. Lin

Micrometer-sized transparent droplets act as natural high-Q cavities to visible light, and this paper shows them to exhibit strongly enhanced dye emission owing to cavity quantum-electrodynamic effects. A vibrating-orifice aerosol generator1 was used to produce a linear stream of virtually identical (less than 2 parts in 105 diameter variation) falling droplets 14 μm diameter, 10-5 M solution of Rhodamine 6G in ethanol; the droplets were excited by a cw argon-ion laser. Droplet emission was examined with a double 1 m Spex spectrograph and a photomultiplier. Recent development of elastic-scattering-size spectroscopy1,2 allowed identification of the various cavity modes contributing to the emission. This was necessary because of the different Q values and spatial properties of the resonant modes. Q values were calculated from Lorenz-Mie theory and were found to be consistent with observed fluorescence linewidths for the experimentally resolvable fourth-order modes. It was experimentally determined that Q's of only 103 were sufficient to observe sizable enhancements in the A coefficient. Lasing was observed to occur at reduced thresholds, e.g., 400 W/cm2 for fourth order modes having Q's of 2 × 103. This corresponds to a cavity induced enhancement in the B coefficient of 103.

Annual Meeting Optical Society of America•Jan 1, 1990•0 citations

Cavity-QED-enhanced spontaneous and stimulated emission in liquid droplets

A. J. Campillo, Jay D. Eversole, Horn-Bond Lin

Several cavity quantum electrodynamic phenomena have been observed in liquid microdroplets. These include cavity-induced spectral changes, emission lifetime modification, and enhanced lasing and Raman gains.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Oct 28, 1992•1 citation

Cavity-QED-enhanced spontaneous emission and lasing in liquid droplets

A. J. Campillo, Jay D. Eversole, Horn-Bond Lin +1 more

Significant cavity QED enhancement have been observed of both spontaneous and stimulated emission in 10- to 14-micrometers diameter liquid microdroplets containing fluorophors. Direct emission lifetime reduction was observed as well as greatly enhanced lasing gain. Use of droplets provides an excellent test of cavity QED theory for spherical geometries. The mode number and order of the spherical cavity resonances responsible for the observed emission peaks were identified and their Q values calculated from Lorenz-Mie theory. An experimental procedure, based on equating stimulated gain to cavity losses, is used to estimate the magnitude of the enhancement. Spherical cavity Qs of only 2600 were found to lead to cavity enhancements of over 100 in the emission cross-section of Rhodamine 6G in agreement with theory.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Sep 1, 1991•0 citations

Cavity-QED enhancement of fluorescence yields in microdroplets

Barnes, William Barclay Whitten, J. Michael Ramsey

Measurements of the integrated fluorescence yield of Rhodamine 6G (R6G) in levitated microdroplets (4 to 16 {mu}m diameter) display a size dependence which is attributed to a decreased probability per excitation cycle of photochemical bleaching as a result of cavity-enhanced spontaneous emission rates. The average number of fluorescence photons detected per molecule in 4 {mu}m droplets (where emission rate enhancement has been previously demonstrated) is shown to be approximately a factor of 2 larger than the yield measured for larger droplets where emission rate enhancement does not occur. Within some simple approximations, these results suggest that essentially no emission rate inhibition occurs in this system. A mechanism based on spectral diffusion is postulated for the apparent absence of cavity-inhibited emission and is illustrated by Monte Carlo calculations using time-dependent lineshape functions.

•Dec 31, 1993•0 citations

Cavity-modified spontaneous-emission rates in liquid microdroplets

H.‐B. Lin, J. D. Eversole, Charles D. Merritt +1 more

We observe significant lifetime modification (both reduction and lengthening) of 610--620-nm light spontaneously emitted by chelated europium ions in 10-\ensuremath{\mu}m-diam dimethylformamide-alcohol solution droplets. The enhancement or inhibition of the Einstein A coefficient over the familiar free-space value is direct evidence of cavity quantum-electrodynamic effects taking place in microdroplets.

Physical Review A•May 1, 1992•105 citations

Detection of Single Molecules in Microcavities

N. Lermer, Michael D. Barnes, C-Y. Kung +2 more

A significant limitation in the detection and spectroscopy of individual dye molecules in liquid room temperature samples is the loss of fluorescence signal through chromophore photobleaching. Although often considered a fundamental restriction on sensitivity, it has been shown that the probability per excitation cycle of photobleaching may be reduced by enhancing the spontaneous emission rate of the chromophore located inside a microdroplet, which acts as a optical cavity. Studies of glycerol microdroplets containing R6G dye molecules, and levitated in a three-dimensional electrodynamic trap, have demonstrated a significant enhancement of both the fluorescence decay rate [1] and the total fluorescence yield [2] of the chromophore. Modification of the emission rate is greatest for molecules located near the surface of small (< 10 μm) microdroplets, where the influence of the droplet cavity modes of the droplet is most significant. To exploit this surface sensitivity, surfactant forms of rhodamine dyes were recently studied [3]. Fluorescence emission of the dye molecules, constrained to the droplet surface and with fixed transition moments perpendicular to the surface normal, were shown to be significantly enhanced at small droplet sizes. Additionally, at larger droplet sizes corresponding to higher droplet Q’s, preferential emission into the cavity modes was observed, however the detection of fluorescence photons was delayed by the storage time of the cavity, which may be on the same order as the fluorescence lifetime. These measurements, performed on relatively concentrated dye solutions, suggest that microcavity effects may be exploited to greatly enhance single molecule detection sensitivity in glycerol microdroplets. Furthermore, the large cavity storage time of the high-Q droplets opens the possibility for re-excitation of the molecule following emission into the droplet resonance, and subsequent stimulated emission, that is, single-molecule lasing.

Laser Applications to Chemical, Security and Environmental Analysis•Jan 1, 1998•0 citations
Laser-induced modification of cavity Q's has been achieved in a microdroplet containing a saturable absorber. The elastic-scattering spectra from such droplets for higher incident intensities show that cavity Q's are increased when the absorption is bleached. The lasing spectra from a droplet containing a saturable absorber and laser dye are modified when an intense bleaching field is injected into the droplet cavity after the pump field has initiated the lasing.
Micrometer-sized transparent droplets act as natural high-Q cavities to visible light, and this paper shows them to exhibit strongly enhanced dye emission owing to cavity quantum-electrodynamic effects. A vibrating-orifice aerosol generator1 was used to produce a linear stream of virtually identical (less than 2 parts in 105 diameter variation) falling droplets 14 μm diameter, 10-5 M solution of Rhodamine 6G in ethanol; the droplets were excited by a cw argon-ion laser. Droplet emission was examined with a double 1 m Spex spectrograph and a photomultiplier. Recent development of elastic-scattering-size spectroscopy1,2 allowed identification of the various cavity modes contributing to the emission. This was necessary because of the different Q values and spatial properties of the resonant modes. Q values were calculated from Lorenz-Mie theory and were found to be consistent with observed fluorescence linewidths for the experimentally resolvable fourth-order modes. It was experimentally determined that Q's of only 103 were sufficient to observe sizable enhancements in the A coefficient. Lasing was observed to occur at reduced thresholds, e.g., 400 W/cm2 for fourth order modes having Q's of 2 × 103. This corresponds to a cavity induced enhancement in the B coefficient of 103.
Significant cavity QED enhancement have been observed of both spontaneous and stimulated emission in 10- to 14-micrometers diameter liquid microdroplets containing fluorophors. Direct emission lifetime reduction was observed as well as greatly enhanced lasing gain. Use of droplets provides an excellent test of cavity QED theory for spherical geometries. The mode number and order of the spherical cavity resonances responsible for the observed emission peaks were identified and their Q values calculated from Lorenz-Mie theory. An experimental procedure, based on equating stimulated gain to cavity losses, is used to estimate the magnitude of the enhancement. Spherical cavity Qs of only 2600 were found to lead to cavity enhancements of over 100 in the emission cross-section of Rhodamine 6G in agreement with theory.
Measurements of the integrated fluorescence yield of Rhodamine 6G (R6G) in levitated microdroplets (4 to 16 {mu}m diameter) display a size dependence which is attributed to a decreased probability per excitation cycle of photochemical bleaching as a result of cavity-enhanced spontaneous emission rates. The average number of fluorescence photons detected per molecule in 4 {mu}m droplets (where emission rate enhancement has been previously demonstrated) is shown to be approximately a factor of 2 larger than the yield measured for larger droplets where emission rate enhancement does not occur. Within some simple approximations, these results suggest that essentially no emission rate inhibition occurs in this system. A mechanism based on spectral diffusion is postulated for the apparent absence of cavity-inhibited emission and is illustrated by Monte Carlo calculations using time-dependent lineshape functions.
A significant limitation in the detection and spectroscopy of individual dye molecules in liquid room temperature samples is the loss of fluorescence signal through chromophore photobleaching. Although often considered a fundamental restriction on sensitivity, it has been shown that the probability per excitation cycle of photobleaching may be reduced by enhancing the spontaneous emission rate of the chromophore located inside a microdroplet, which acts as a optical cavity. Studies of glycerol microdroplets containing R6G dye molecules, and levitated in a three-dimensional electrodynamic trap, have demonstrated a significant enhancement of both the fluorescence decay rate [1] and the total fluorescence yield [2] of the chromophore. Modification of the emission rate is greatest for molecules located near the surface of small (< 10 μm) microdroplets, where the influence of the droplet cavity modes of the droplet is most significant. To exploit this surface sensitivity, surfactant forms of rhodamine dyes were recently studied [3]. Fluorescence emission of the dye molecules, constrained to the droplet surface and with fixed transition moments perpendicular to the surface normal, were shown to be significantly enhanced at small droplet sizes. Additionally, at larger droplet sizes corresponding to higher droplet Q’s, preferential emission into the cavity modes was observed, however the detection of fluorescence photons was delayed by the storage time of the cavity, which may be on the same order as the fluorescence lifetime. These measurements, performed on relatively concentrated dye solutions, suggest that microcavity effects may be exploited to greatly enhance single molecule detection sensitivity in glycerol microdroplets. Furthermore, the large cavity storage time of the high-Q droplets opens the possibility for re-excitation of the molecule following emission into the droplet resonance, and subsequent stimulated emission, that is, single-molecule lasing.