Abstract

This paper describes the generation and optical characterization of a series of dye-doped droplet-based optical microcavities with continuously decreasing radius in a microfluidic channel. A flow-focusing nozzle generated the droplets (~21 μm in radius) using benzyl alcohol as the disperse phase and water as the continuous phase. As these drops moved down the channel, they dissolved, and their size decreased. The emission characteristics from the drops could be matched to the whispering gallery modes from spherical micro-cavities. The wavelength of emission from the drops changed from 700 to 620 nm as the radius of the drops decreased from 21 μm to 7 μm. This range of tunability in wavelengths was larger than that reported in previous work on droplet-based cavities.

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    [CrossRef] [PubMed]
  4. H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Evaporation and condensation rates of liquid droplets deduced from structure resonances in the fluorescence spectra,” Opt. Lett. 9(7), 273–275 (1984).
    [CrossRef] [PubMed]
  5. H. M. Tzeng, M. B. Long, R. K. Chang, and P. W. Barber, “Laser-induced shape distortions of flowing droplets deduced from morphology-dependent resonances in fluorescence spectra,” Opt. Lett. 10(5), 209–211 (1985).
    [CrossRef] [PubMed]
  6. S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
    [CrossRef] [PubMed]
  7. J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
    [CrossRef] [PubMed]
  8. M. Saito, H. Shimatani, and H. Naruhashi, “Tunable whispering gallery mode emission from a microdroplet in elastomer,” Opt. Express 16(16), 11915–11919 (2008).
    [CrossRef] [PubMed]
  9. S. X. Qian, J. B. Snow, H. M. Tzeng, and R. K. Chang, “Lasing droplets: highlighting the liquid-air interface by laser emission,” Science 231(4737), 486–488 (1986).
    [CrossRef] [PubMed]
  10. M. M. Mazumder, G. Chen, P. J. Kindlmann, R. K. Chang, and J. B. Gillespie, “Temperature-dependent wavelength shifts of dye lasing in microdroplets with a thermochromic additive,” Opt. Lett. 20(16), 1668–1670 (1995).
    [CrossRef] [PubMed]
  11. M. M. Mazumder, G. Chen, R. K. Chang, and J. B. Gillespie, “Wavelength shifts of dye lasing in microdroplets: effect of absorption change,” Opt. Lett. 20(8), 878–880 (1995).
    [CrossRef] [PubMed]
  12. H. B. Lin, A. L. Huston, B. L. Justus, and A. J. Campillo, “Some characteristics of a droplet whispering-gallery-mode laser,” Opt. Lett. 11(10), 614–616 (1986).
    [CrossRef] [PubMed]
  13. H. B. Lin, J. D. Eversole, and A. J. Campillo, “Spectral properties of lasing microdroplets,” J. Opt. Soc. Am. B 9(1), 43–50 (1992).
    [CrossRef]
  14. A. Kiraz, A. Kurt, M. A. Dündar, and A. L. Demirel, “Simple largely tunable optical microcavity,” Appl. Phys. Lett. 89(8), 081118 (2006).
    [CrossRef]
  15. C. G. Garrett, W. Kaiser, and W. L. Bond, “Stimulated emission into optical whispering modes of spheres,” Phys. Rev. 124(6), 1807–1809 (1961).
    [CrossRef]
  16. G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
    [CrossRef] [PubMed]
  17. A. J. Campillo, J. D. Eversole, and H. B. Lin, “Cavity quantum electrodynamic enhancement of stimulated emission in microdroplets,” Phys. Rev. Lett. 67(4), 437–440 (1991).
    [CrossRef] [PubMed]
  18. P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
    [CrossRef]
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  20. P. Garstecki, H. A. Stone, and G. M. Whitesides, “Mechanism for flow-rate controlled breakup in confined geometries: a route to monodisperse emulsions,” Phys. Rev. Lett. 94(16), 164501 (2005).
    [CrossRef] [PubMed]
  21. S. L. Anna, N. Bontoux, and H. A. Stone, “Formation of dispersions using “flow focusing” in microchannels,” Appl. Phys. Lett. 82(3), 364–366 (2003).
    [CrossRef]
  22. J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
    [CrossRef] [PubMed]
  23. P. Garstecki, M. J. Fuerstman, H. A. Stone, and G. M. Whitesides, “Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up,” Lab Chip 6(3), 437–446 (2006).
    [CrossRef] [PubMed]
  24. S. K. Y. Tang, C. A. Stan, and G. M. Whitesides, “Dynamically reconfigurable liquid-core liquid-cladding lens in a microfluidic channel,” Lab Chip 8(3), 395–401 (2008).
    [CrossRef] [PubMed]
  25. W. Lee, L. M. Walker, and S. L. Anna, “Role of geometry and fluid properties in droplet and thread formation processes in planar flow focusing,” Phys. Fluids 21(3), 032103 (2009).
    [CrossRef]
  26. The polydispersity is calculated as s/d, where s is the standard deviation in drop diameters, and d is the average drop diameter. We imaged 60 drops and used a custom-made Matlab program to extract the droplet diameters.
  27. To prepare the saturated solutions, we mixed 1:1 ratio of benzyl alcohol and water. We stirred the mixture for 30 min at 60 degree C. We then centrifuged the mixture, and extracted the top phase (water saturated with benzyl alcohol) and bottom phase (benzyl alcohol saturated with water).
  28. J. I. Park, Z. Nie, A. Kumachev, and E. Kumacheva, “A microfluidic route to small CO2 microbubbles with narrow size distribution,” Soft Matter 6(3), 630–634 (2010).
    [CrossRef]
  29. C. C. Lam, P. T. Leung, and K. Young, “Explicit asymptotic formulas for the positions, widths, and strengths of resonances in Mie scattering,” J. Opt. Soc. Am. B 9(9), 1585–1592 (1992).
    [CrossRef]
  30. J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
    [CrossRef]
  31. J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
    [CrossRef] [PubMed]
  32. J. A. Stratton, Electromagnetic Theory (McGraw-Hill, 1941).

2010

J. I. Park, Z. Nie, A. Kumachev, and E. Kumacheva, “A microfluidic route to small CO2 microbubbles with narrow size distribution,” Soft Matter 6(3), 630–634 (2010).
[CrossRef]

2009

W. Lee, L. M. Walker, and S. L. Anna, “Role of geometry and fluid properties in droplet and thread formation processes in planar flow focusing,” Phys. Fluids 21(3), 032103 (2009).
[CrossRef]

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

2008

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

M. Saito, H. Shimatani, and H. Naruhashi, “Tunable whispering gallery mode emission from a microdroplet in elastomer,” Opt. Express 16(16), 11915–11919 (2008).
[CrossRef] [PubMed]

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

S. K. Y. Tang, C. A. Stan, and G. M. Whitesides, “Dynamically reconfigurable liquid-core liquid-cladding lens in a microfluidic channel,” Lab Chip 8(3), 395–401 (2008).
[CrossRef] [PubMed]

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

2006

P. Garstecki, M. J. Fuerstman, H. A. Stone, and G. M. Whitesides, “Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up,” Lab Chip 6(3), 437–446 (2006).
[CrossRef] [PubMed]

A. Kiraz, A. Kurt, M. A. Dündar, and A. L. Demirel, “Simple largely tunable optical microcavity,” Appl. Phys. Lett. 89(8), 081118 (2006).
[CrossRef]

2005

P. Garstecki, H. A. Stone, and G. M. Whitesides, “Mechanism for flow-rate controlled breakup in confined geometries: a route to monodisperse emulsions,” Phys. Rev. Lett. 94(16), 164501 (2005).
[CrossRef] [PubMed]

2004

P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
[CrossRef]

2003

S. L. Anna, N. Bontoux, and H. A. Stone, “Formation of dispersions using “flow focusing” in microchannels,” Appl. Phys. Lett. 82(3), 364–366 (2003).
[CrossRef]

2000

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

1995

M. M. Mazumder, G. Chen, P. J. Kindlmann, R. K. Chang, and J. B. Gillespie, “Temperature-dependent wavelength shifts of dye lasing in microdroplets with a thermochromic additive,” Opt. Lett. 20(16), 1668–1670 (1995).
[CrossRef] [PubMed]

M. M. Mazumder, G. Chen, R. K. Chang, and J. B. Gillespie, “Wavelength shifts of dye lasing in microdroplets: effect of absorption change,” Opt. Lett. 20(8), 878–880 (1995).
[CrossRef] [PubMed]

1993

G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
[CrossRef] [PubMed]

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

1992

C. C. Lam, P. T. Leung, and K. Young, “Explicit asymptotic formulas for the positions, widths, and strengths of resonances in Mie scattering,” J. Opt. Soc. Am. B 9(9), 1585–1592 (1992).
[CrossRef]

H. B. Lin, J. D. Eversole, and A. J. Campillo, “Spectral properties of lasing microdroplets,” J. Opt. Soc. Am. B 9(1), 43–50 (1992).
[CrossRef]

1991

A. J. Campillo, J. D. Eversole, and H. B. Lin, “Cavity quantum electrodynamic enhancement of stimulated emission in microdroplets,” Phys. Rev. Lett. 67(4), 437–440 (1991).
[CrossRef] [PubMed]

1986

H. B. Lin, A. L. Huston, B. L. Justus, and A. J. Campillo, “Some characteristics of a droplet whispering-gallery-mode laser,” Opt. Lett. 11(10), 614–616 (1986).
[CrossRef] [PubMed]

S. X. Qian, J. B. Snow, H. M. Tzeng, and R. K. Chang, “Lasing droplets: highlighting the liquid-air interface by laser emission,” Science 231(4737), 486–488 (1986).
[CrossRef] [PubMed]

1985

H. M. Tzeng, M. B. Long, R. K. Chang, and P. W. Barber, “Laser-induced shape distortions of flowing droplets deduced from morphology-dependent resonances in fluorescence spectra,” Opt. Lett. 10(5), 209–211 (1985).
[CrossRef] [PubMed]

1984

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Laser emission from individual droplets at wavelengths corresponding to morphology-dependent resonances,” Opt. Lett. 9(11), 499–501 (1984).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Evaporation and condensation rates of liquid droplets deduced from structure resonances in the fluorescence spectra,” Opt. Lett. 9(7), 273–275 (1984).
[CrossRef] [PubMed]

1961

C. G. Garrett, W. Kaiser, and W. L. Bond, “Stimulated emission into optical whispering modes of spheres,” Phys. Rev. 124(6), 1807–1809 (1961).
[CrossRef]

Abate, A. R.

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

Agresti, J. J.

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

Anderson, J. R.

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

Anna, S. L.

W. Lee, L. M. Walker, and S. L. Anna, “Role of geometry and fluid properties in droplet and thread formation processes in planar flow focusing,” Phys. Fluids 21(3), 032103 (2009).
[CrossRef]

S. L. Anna, N. Bontoux, and H. A. Stone, “Formation of dispersions using “flow focusing” in microchannels,” Appl. Phys. Lett. 82(3), 364–366 (2003).
[CrossRef]

Barber, P. W.

H. M. Tzeng, M. B. Long, R. K. Chang, and P. W. Barber, “Laser-induced shape distortions of flowing droplets deduced from morphology-dependent resonances in fluorescence spectra,” Opt. Lett. 10(5), 209–211 (1985).
[CrossRef] [PubMed]

Baret, J.-C.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Blouwolff, J.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Bond, W. L.

C. G. Garrett, W. Kaiser, and W. L. Bond, “Stimulated emission into optical whispering modes of spheres,” Phys. Rev. 124(6), 1807–1809 (1961).
[CrossRef]

Bontoux, N.

S. L. Anna, N. Bontoux, and H. A. Stone, “Formation of dispersions using “flow focusing” in microchannels,” Appl. Phys. Lett. 82(3), 364–366 (2003).
[CrossRef]

Campillo, A. J.

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

H. B. Lin, J. D. Eversole, and A. J. Campillo, “Spectral properties of lasing microdroplets,” J. Opt. Soc. Am. B 9(1), 43–50 (1992).
[CrossRef]

A. J. Campillo, J. D. Eversole, and H. B. Lin, “Cavity quantum electrodynamic enhancement of stimulated emission in microdroplets,” Phys. Rev. Lett. 67(4), 437–440 (1991).
[CrossRef] [PubMed]

H. B. Lin, A. L. Huston, B. L. Justus, and A. J. Campillo, “Some characteristics of a droplet whispering-gallery-mode laser,” Opt. Lett. 11(10), 614–616 (1986).
[CrossRef] [PubMed]

Chang, R. K.

M. M. Mazumder, G. Chen, P. J. Kindlmann, R. K. Chang, and J. B. Gillespie, “Temperature-dependent wavelength shifts of dye lasing in microdroplets with a thermochromic additive,” Opt. Lett. 20(16), 1668–1670 (1995).
[CrossRef] [PubMed]

M. M. Mazumder, G. Chen, R. K. Chang, and J. B. Gillespie, “Wavelength shifts of dye lasing in microdroplets: effect of absorption change,” Opt. Lett. 20(8), 878–880 (1995).
[CrossRef] [PubMed]

G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
[CrossRef] [PubMed]

S. X. Qian, J. B. Snow, H. M. Tzeng, and R. K. Chang, “Lasing droplets: highlighting the liquid-air interface by laser emission,” Science 231(4737), 486–488 (1986).
[CrossRef] [PubMed]

H. M. Tzeng, M. B. Long, R. K. Chang, and P. W. Barber, “Laser-induced shape distortions of flowing droplets deduced from morphology-dependent resonances in fluorescence spectra,” Opt. Lett. 10(5), 209–211 (1985).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Laser emission from individual droplets at wavelengths corresponding to morphology-dependent resonances,” Opt. Lett. 9(11), 499–501 (1984).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Evaporation and condensation rates of liquid droplets deduced from structure resonances in the fluorescence spectra,” Opt. Lett. 9(7), 273–275 (1984).
[CrossRef] [PubMed]

Chemla, Y. R.

G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
[CrossRef] [PubMed]

Chen, G.

M. M. Mazumder, G. Chen, P. J. Kindlmann, R. K. Chang, and J. B. Gillespie, “Temperature-dependent wavelength shifts of dye lasing in microdroplets with a thermochromic additive,” Opt. Lett. 20(16), 1668–1670 (1995).
[CrossRef] [PubMed]

M. M. Mazumder, G. Chen, R. K. Chang, and J. B. Gillespie, “Wavelength shifts of dye lasing in microdroplets: effect of absorption change,” Opt. Lett. 20(8), 878–880 (1995).
[CrossRef] [PubMed]

G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
[CrossRef] [PubMed]

Chiu, D. T.

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

Clausell-Tormos, J.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Demirel, A. L.

A. Kiraz, A. Kurt, M. A. Dündar, and A. L. Demirel, “Simple largely tunable optical microcavity,” Appl. Phys. Lett. 89(8), 081118 (2006).
[CrossRef]

DiLuzio, W.

P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
[CrossRef]

Duan, H.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Duffy, D. C.

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

Dündar, M. A.

A. Kiraz, A. Kurt, M. A. Dündar, and A. L. Demirel, “Simple largely tunable optical microcavity,” Appl. Phys. Lett. 89(8), 081118 (2006).
[CrossRef]

El-Harrak, A.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Eversole, J. D.

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

H. B. Lin, J. D. Eversole, and A. J. Campillo, “Spectral properties of lasing microdroplets,” J. Opt. Soc. Am. B 9(1), 43–50 (1992).
[CrossRef]

A. J. Campillo, J. D. Eversole, and H. B. Lin, “Cavity quantum electrodynamic enhancement of stimulated emission in microdroplets,” Phys. Rev. Lett. 67(4), 437–440 (1991).
[CrossRef] [PubMed]

Frenz, L.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Fuerstman, M. J.

P. Garstecki, M. J. Fuerstman, H. A. Stone, and G. M. Whitesides, “Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up,” Lab Chip 6(3), 437–446 (2006).
[CrossRef] [PubMed]

Garrett, C. G.

C. G. Garrett, W. Kaiser, and W. L. Bond, “Stimulated emission into optical whispering modes of spheres,” Phys. Rev. 124(6), 1807–1809 (1961).
[CrossRef]

Garstecki, P.

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

P. Garstecki, M. J. Fuerstman, H. A. Stone, and G. M. Whitesides, “Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up,” Lab Chip 6(3), 437–446 (2006).
[CrossRef] [PubMed]

P. Garstecki, H. A. Stone, and G. M. Whitesides, “Mechanism for flow-rate controlled breakup in confined geometries: a route to monodisperse emulsions,” Phys. Rev. Lett. 94(16), 164501 (2005).
[CrossRef] [PubMed]

P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
[CrossRef]

Gillespie, J. B.

M. M. Mazumder, G. Chen, R. K. Chang, and J. B. Gillespie, “Wavelength shifts of dye lasing in microdroplets: effect of absorption change,” Opt. Lett. 20(8), 878–880 (1995).
[CrossRef] [PubMed]

M. M. Mazumder, G. Chen, P. J. Kindlmann, R. K. Chang, and J. B. Gillespie, “Temperature-dependent wavelength shifts of dye lasing in microdroplets with a thermochromic additive,” Opt. Lett. 20(16), 1668–1670 (1995).
[CrossRef] [PubMed]

Gitlin, I.

P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
[CrossRef]

Griffiths, A. D.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Hill, S. C.

G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
[CrossRef] [PubMed]

Holtze, C.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Humphry, K. J.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Huston, A. L.

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

H. B. Lin, A. L. Huston, B. L. Justus, and A. J. Campillo, “Some characteristics of a droplet whispering-gallery-mode laser,” Opt. Lett. 11(10), 614–616 (1986).
[CrossRef] [PubMed]

Justus, B. L.

H. B. Lin, A. L. Huston, B. L. Justus, and A. J. Campillo, “Some characteristics of a droplet whispering-gallery-mode laser,” Opt. Lett. 11(10), 614–616 (1986).
[CrossRef] [PubMed]

Kaiser, W.

C. G. Garrett, W. Kaiser, and W. L. Bond, “Stimulated emission into optical whispering modes of spheres,” Phys. Rev. 124(6), 1807–1809 (1961).
[CrossRef]

Kindlmann, P. J.

M. M. Mazumder, G. Chen, P. J. Kindlmann, R. K. Chang, and J. B. Gillespie, “Temperature-dependent wavelength shifts of dye lasing in microdroplets with a thermochromic additive,” Opt. Lett. 20(16), 1668–1670 (1995).
[CrossRef] [PubMed]

Kiraz, A.

A. Kiraz, A. Kurt, M. A. Dündar, and A. L. Demirel, “Simple largely tunable optical microcavity,” Appl. Phys. Lett. 89(8), 081118 (2006).
[CrossRef]

Köster, S.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Kumachev, A.

J. I. Park, Z. Nie, A. Kumachev, and E. Kumacheva, “A microfluidic route to small CO2 microbubbles with narrow size distribution,” Soft Matter 6(3), 630–634 (2010).
[CrossRef]

Kumacheva, E.

J. I. Park, Z. Nie, A. Kumachev, and E. Kumacheva, “A microfluidic route to small CO2 microbubbles with narrow size distribution,” Soft Matter 6(3), 630–634 (2010).
[CrossRef]

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
[CrossRef]

Kurt, A.

A. Kiraz, A. Kurt, M. A. Dündar, and A. L. Demirel, “Simple largely tunable optical microcavity,” Appl. Phys. Lett. 89(8), 081118 (2006).
[CrossRef]

Lam, C. C.

C. C. Lam, P. T. Leung, and K. Young, “Explicit asymptotic formulas for the positions, widths, and strengths of resonances in Mie scattering,” J. Opt. Soc. Am. B 9(9), 1585–1592 (1992).
[CrossRef]

Lee, W.

W. Lee, L. M. Walker, and S. L. Anna, “Role of geometry and fluid properties in droplet and thread formation processes in planar flow focusing,” Phys. Fluids 21(3), 032103 (2009).
[CrossRef]

Leung, P. T.

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

C. C. Lam, P. T. Leung, and K. Young, “Explicit asymptotic formulas for the positions, widths, and strengths of resonances in Mie scattering,” J. Opt. Soc. Am. B 9(9), 1585–1592 (1992).
[CrossRef]

Lewis, P. C.

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

Li, Z.

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

Lieber, D.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Lin, H. B.

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

H. B. Lin, J. D. Eversole, and A. J. Campillo, “Spectral properties of lasing microdroplets,” J. Opt. Soc. Am. B 9(1), 43–50 (1992).
[CrossRef]

A. J. Campillo, J. D. Eversole, and H. B. Lin, “Cavity quantum electrodynamic enhancement of stimulated emission in microdroplets,” Phys. Rev. Lett. 67(4), 437–440 (1991).
[CrossRef] [PubMed]

H. B. Lin, A. L. Huston, B. L. Justus, and A. J. Campillo, “Some characteristics of a droplet whispering-gallery-mode laser,” Opt. Lett. 11(10), 614–616 (1986).
[CrossRef] [PubMed]

Liu, S. Y.

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

Long, M. B.

H. M. Tzeng, M. B. Long, R. K. Chang, and P. W. Barber, “Laser-induced shape distortions of flowing droplets deduced from morphology-dependent resonances in fluorescence spectra,” Opt. Lett. 10(5), 209–211 (1985).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Laser emission from individual droplets at wavelengths corresponding to morphology-dependent resonances,” Opt. Lett. 9(11), 499–501 (1984).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Evaporation and condensation rates of liquid droplets deduced from structure resonances in the fluorescence spectra,” Opt. Lett. 9(7), 273–275 (1984).
[CrossRef] [PubMed]

Lu, Z. H.

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

Mazumder, M. M.

M. M. Mazumder, G. Chen, R. K. Chang, and J. B. Gillespie, “Wavelength shifts of dye lasing in microdroplets: effect of absorption change,” Opt. Lett. 20(8), 878–880 (1995).
[CrossRef] [PubMed]

M. M. Mazumder, G. Chen, P. J. Kindlmann, R. K. Chang, and J. B. Gillespie, “Temperature-dependent wavelength shifts of dye lasing in microdroplets with a thermochromic additive,” Opt. Lett. 20(16), 1668–1670 (1995).
[CrossRef] [PubMed]

G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
[CrossRef] [PubMed]

McDonald, J. C.

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

Merten, C. A.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Miller, O. J.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Mok, M.

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

Mondia, J. P.

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

Naruhashi, H.

M. Saito, H. Shimatani, and H. Naruhashi, “Tunable whispering gallery mode emission from a microdroplet in elastomer,” Opt. Express 16(16), 11915–11919 (2008).
[CrossRef] [PubMed]

Nie, Z.

J. I. Park, Z. Nie, A. Kumachev, and E. Kumacheva, “A microfluidic route to small CO2 microbubbles with narrow size distribution,” Soft Matter 6(3), 630–634 (2010).
[CrossRef]

Nie, Z. H.

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

Park, J. I.

J. I. Park, Z. Nie, A. Kumachev, and E. Kumacheva, “A microfluidic route to small CO2 microbubbles with narrow size distribution,” Soft Matter 6(3), 630–634 (2010).
[CrossRef]

Psaltis, D.

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

Qian, S. X.

S. X. Qian, J. B. Snow, H. M. Tzeng, and R. K. Chang, “Lasing droplets: highlighting the liquid-air interface by laser emission,” Science 231(4737), 486–488 (1986).
[CrossRef] [PubMed]

Rogach, A. L.

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

Saito, M.

M. Saito, H. Shimatani, and H. Naruhashi, “Tunable whispering gallery mode emission from a microdroplet in elastomer,” Opt. Express 16(16), 11915–11919 (2008).
[CrossRef] [PubMed]

Schäfer, J.

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

Schueller, O. J.

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

Seo, M. S.

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

Serpenguzel, A.

G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
[CrossRef] [PubMed]

Sharma, R.

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

Shimatani, H.

M. Saito, H. Shimatani, and H. Naruhashi, “Tunable whispering gallery mode emission from a microdroplet in elastomer,” Opt. Express 16(16), 11915–11919 (2008).
[CrossRef] [PubMed]

Snow, J. B.

S. X. Qian, J. B. Snow, H. M. Tzeng, and R. K. Chang, “Lasing droplets: highlighting the liquid-air interface by laser emission,” Science 231(4737), 486–488 (1986).
[CrossRef] [PubMed]

Stan, C. A.

S. K. Y. Tang, C. A. Stan, and G. M. Whitesides, “Dynamically reconfigurable liquid-core liquid-cladding lens in a microfluidic channel,” Lab Chip 8(3), 395–401 (2008).
[CrossRef] [PubMed]

Stone, H. A.

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

P. Garstecki, M. J. Fuerstman, H. A. Stone, and G. M. Whitesides, “Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up,” Lab Chip 6(3), 437–446 (2006).
[CrossRef] [PubMed]

P. Garstecki, H. A. Stone, and G. M. Whitesides, “Mechanism for flow-rate controlled breakup in confined geometries: a route to monodisperse emulsions,” Phys. Rev. Lett. 94(16), 164501 (2005).
[CrossRef] [PubMed]

P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
[CrossRef]

S. L. Anna, N. Bontoux, and H. A. Stone, “Formation of dispersions using “flow focusing” in microchannels,” Appl. Phys. Lett. 82(3), 364–366 (2003).
[CrossRef]

Susha, A. S.

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

Tang, S. K. Y.

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

S. K. Y. Tang, C. A. Stan, and G. M. Whitesides, “Dynamically reconfigurable liquid-core liquid-cladding lens in a microfluidic channel,” Lab Chip 8(3), 395–401 (2008).
[CrossRef] [PubMed]

Tzeng, H. M.

S. X. Qian, J. B. Snow, H. M. Tzeng, and R. K. Chang, “Lasing droplets: highlighting the liquid-air interface by laser emission,” Science 231(4737), 486–488 (1986).
[CrossRef] [PubMed]

H. M. Tzeng, M. B. Long, R. K. Chang, and P. W. Barber, “Laser-induced shape distortions of flowing droplets deduced from morphology-dependent resonances in fluorescence spectra,” Opt. Lett. 10(5), 209–211 (1985).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Laser emission from individual droplets at wavelengths corresponding to morphology-dependent resonances,” Opt. Lett. 9(11), 499–501 (1984).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Evaporation and condensation rates of liquid droplets deduced from structure resonances in the fluorescence spectra,” Opt. Lett. 9(7), 273–275 (1984).
[CrossRef] [PubMed]

Walker, L. M.

W. Lee, L. M. Walker, and S. L. Anna, “Role of geometry and fluid properties in droplet and thread formation processes in planar flow focusing,” Phys. Fluids 21(3), 032103 (2009).
[CrossRef]

Wall, K. F.

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Laser emission from individual droplets at wavelengths corresponding to morphology-dependent resonances,” Opt. Lett. 9(11), 499–501 (1984).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Evaporation and condensation rates of liquid droplets deduced from structure resonances in the fluorescence spectra,” Opt. Lett. 9(7), 273–275 (1984).
[CrossRef] [PubMed]

Wang, L. J.

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

Weitz, D. A.

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Whitesides, G. M.

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

S. K. Y. Tang, C. A. Stan, and G. M. Whitesides, “Dynamically reconfigurable liquid-core liquid-cladding lens in a microfluidic channel,” Lab Chip 8(3), 395–401 (2008).
[CrossRef] [PubMed]

P. Garstecki, M. J. Fuerstman, H. A. Stone, and G. M. Whitesides, “Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up,” Lab Chip 6(3), 437–446 (2006).
[CrossRef] [PubMed]

P. Garstecki, H. A. Stone, and G. M. Whitesides, “Mechanism for flow-rate controlled breakup in confined geometries: a route to monodisperse emulsions,” Phys. Rev. Lett. 94(16), 164501 (2005).
[CrossRef] [PubMed]

P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
[CrossRef]

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

Wu, H.

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

Xu, S. Q.

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

Young, K.

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

C. C. Lam, P. T. Leung, and K. Young, “Explicit asymptotic formulas for the positions, widths, and strengths of resonances in Mie scattering,” J. Opt. Soc. Am. B 9(9), 1585–1592 (1992).
[CrossRef]

Appl. Phys. Lett.

A. Kiraz, A. Kurt, M. A. Dündar, and A. L. Demirel, “Simple largely tunable optical microcavity,” Appl. Phys. Lett. 89(8), 081118 (2006).
[CrossRef]

P. Garstecki, I. Gitlin, W. DiLuzio, G. M. Whitesides, E. Kumacheva, and H. A. Stone, “Formation of monodisperse bubbles in a microfluidic flow-focusing device,” Appl. Phys. Lett. 85(13), 2649–2651 (2004).
[CrossRef]

S. L. Anna, N. Bontoux, and H. A. Stone, “Formation of dispersions using “flow focusing” in microchannels,” Appl. Phys. Lett. 82(3), 364–366 (2003).
[CrossRef]

Chem. Biol.

J. Clausell-Tormos, D. Lieber, J.-C. Baret, A. El-Harrak, O. J. Miller, L. Frenz, J. Blouwolff, K. J. Humphry, S. Köster, H. Duan, C. Holtze, D. A. Weitz, A. D. Griffiths, and C. A. Merten, “Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms,” Chem. Biol. 15(5), 427–437 (2008).
[CrossRef] [PubMed]

Electrophoresis

J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. Schueller, and G. M. Whitesides, “Fabrication of microfluidic systems in poly(dimethylsiloxane),” Electrophoresis 21(1), 27–40 (2000).
[CrossRef] [PubMed]

J. Opt. Soc. Am. B

H. B. Lin, J. D. Eversole, and A. J. Campillo, “Spectral properties of lasing microdroplets,” J. Opt. Soc. Am. B 9(1), 43–50 (1992).
[CrossRef]

C. C. Lam, P. T. Leung, and K. Young, “Explicit asymptotic formulas for the positions, widths, and strengths of resonances in Mie scattering,” J. Opt. Soc. Am. B 9(9), 1585–1592 (1992).
[CrossRef]

J. D. Eversole, H. B. Lin, A. L. Huston, A. J. Campillo, P. T. Leung, S. Y. Liu, and K. Young, “High-precision identification of morphology-dependent resonances in optical processes in microdroplets,” J. Opt. Soc. Am. B 10(10), 1955–1968 (1993).
[CrossRef]

Lab Chip

P. Garstecki, M. J. Fuerstman, H. A. Stone, and G. M. Whitesides, “Formation of droplets and bubbles in a microfluidic T-junction-scaling and mechanism of break-up,” Lab Chip 6(3), 437–446 (2006).
[CrossRef] [PubMed]

S. K. Y. Tang, C. A. Stan, and G. M. Whitesides, “Dynamically reconfigurable liquid-core liquid-cladding lens in a microfluidic channel,” Lab Chip 8(3), 395–401 (2008).
[CrossRef] [PubMed]

S. K. Y. Tang, Z. Li, A. R. Abate, J. J. Agresti, D. A. Weitz, D. Psaltis, and G. M. Whitesides, “A multi-color fast-switching microfluidic droplet dye laser,” Lab Chip 9(19), 2767–2771 (2009).
[CrossRef] [PubMed]

Microfluid. Nanofluid.

Z. H. Nie, M. S. Seo, S. Q. Xu, P. C. Lewis, M. Mok, E. Kumacheva, G. M. Whitesides, P. Garstecki, and H. A. Stone, “Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids,” Microfluid. Nanofluid. 5, 585–594 (2008).

Nano Lett.

J. Schäfer, J. P. Mondia, R. Sharma, Z. H. Lu, A. S. Susha, A. L. Rogach, and L. J. Wang, “Quantum dot microdrop laser,” Nano Lett. 8(6), 1709–1712 (2008).
[CrossRef] [PubMed]

Opt. Express

M. Saito, H. Shimatani, and H. Naruhashi, “Tunable whispering gallery mode emission from a microdroplet in elastomer,” Opt. Express 16(16), 11915–11919 (2008).
[CrossRef] [PubMed]

Opt. Lett.

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Laser emission from individual droplets at wavelengths corresponding to morphology-dependent resonances,” Opt. Lett. 9(11), 499–501 (1984).
[CrossRef] [PubMed]

H. M. Tzeng, K. F. Wall, M. B. Long, and R. K. Chang, “Evaporation and condensation rates of liquid droplets deduced from structure resonances in the fluorescence spectra,” Opt. Lett. 9(7), 273–275 (1984).
[CrossRef] [PubMed]

H. M. Tzeng, M. B. Long, R. K. Chang, and P. W. Barber, “Laser-induced shape distortions of flowing droplets deduced from morphology-dependent resonances in fluorescence spectra,” Opt. Lett. 10(5), 209–211 (1985).
[CrossRef] [PubMed]

G. Chen, M. M. Mazumder, Y. R. Chemla, A. Serpenguzel, R. K. Chang, and S. C. Hill, “Wavelength variation of laser emission along the entire rim of slightly deformed microdroplets,” Opt. Lett. 18(23), 1993–1995 (1993).
[CrossRef] [PubMed]

M. M. Mazumder, G. Chen, P. J. Kindlmann, R. K. Chang, and J. B. Gillespie, “Temperature-dependent wavelength shifts of dye lasing in microdroplets with a thermochromic additive,” Opt. Lett. 20(16), 1668–1670 (1995).
[CrossRef] [PubMed]

M. M. Mazumder, G. Chen, R. K. Chang, and J. B. Gillespie, “Wavelength shifts of dye lasing in microdroplets: effect of absorption change,” Opt. Lett. 20(8), 878–880 (1995).
[CrossRef] [PubMed]

H. B. Lin, A. L. Huston, B. L. Justus, and A. J. Campillo, “Some characteristics of a droplet whispering-gallery-mode laser,” Opt. Lett. 11(10), 614–616 (1986).
[CrossRef] [PubMed]

Phys. Fluids

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[CrossRef]

Phys. Rev.

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[CrossRef]

Phys. Rev. Lett.

A. J. Campillo, J. D. Eversole, and H. B. Lin, “Cavity quantum electrodynamic enhancement of stimulated emission in microdroplets,” Phys. Rev. Lett. 67(4), 437–440 (1991).
[CrossRef] [PubMed]

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[CrossRef] [PubMed]

Science

S. X. Qian, J. B. Snow, H. M. Tzeng, and R. K. Chang, “Lasing droplets: highlighting the liquid-air interface by laser emission,” Science 231(4737), 486–488 (1986).
[CrossRef] [PubMed]

Soft Matter

J. I. Park, Z. Nie, A. Kumachev, and E. Kumacheva, “A microfluidic route to small CO2 microbubbles with narrow size distribution,” Soft Matter 6(3), 630–634 (2010).
[CrossRef]

Other

The polydispersity is calculated as s/d, where s is the standard deviation in drop diameters, and d is the average drop diameter. We imaged 60 drops and used a custom-made Matlab program to extract the droplet diameters.

To prepare the saturated solutions, we mixed 1:1 ratio of benzyl alcohol and water. We stirred the mixture for 30 min at 60 degree C. We then centrifuged the mixture, and extracted the top phase (water saturated with benzyl alcohol) and bottom phase (benzyl alcohol saturated with water).

J. A. Stratton, Electromagnetic Theory (McGraw-Hill, 1941).

S. C. Hill, and R. E. Benner, “Morphology-dependent resonances,” in Optical Effects Associated with Small Particles, R. K. Chang, and P. W. Barber, eds. (World Scientific Publishing Co., 1988), pp. 3–61.

R. K. Chang, and A. J. Campillo, Optical Processes in Microcavities (World Scientific Publishing Co., 1996).

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Figures (5)

Fig. 1
Fig. 1

a) shows a schematic diagram of the droplet laser. The width of the channel at the flow-focusing nozzle was 15 μm. The width of the channel was 60 μm at y = 0, and narrowed to 20 μm at y = 16 cm. The height of the channel (in the z-direction) was 43 μm. Drops containing 1 mM solution of rhodamine 640 perchlorate in benzyl alcohol dissolved into water as they travelled in the channel, and their sizes decreased. The concentration of rhodamine increased as the volume of the drops decreased. This effect on the emission spectrum from the droplet cavities was insignificant (see text). b) The droplets were optically excited by a pulsed frequency-doubled Nd:YAG at repetition rate of 1 kHz, much higher than the rate of generation of drops (~125 drops/second). The excitation beam was directed perpendicular to the plane of the microchannel (in the z-direction). The optical output from the drops was collected through an objective behind the channel in the same direction as the pump beam (z-direction). The dichroic mirror reflects light with wavelength at 532 nm, and transmits light with wavelengths > 532 nm.

Fig. 2
Fig. 2

a) shows a snapshot of the device during its operation. b) shows the distribution of sizes of drops generated by the flow-focusing nozzle. The polydispersity of drop sizes was less than 1% (see text). c) shows the radius of the drops at different distances down the channel. The rate of flow of the carrier fluid was 200 μL h−1, and that of the disperse phase was 20 μL h−1. The insets show images of the drops at different positions in the channel. The image of the smallest drop appears smeared because the drop was moving faster than the frame rate of the camera. d) shows the surface area of the drops as a function of their residence time in the channel. The decrease in surface area follows a first-order kinetics with rate constant k = −0.92 s−1. The R2 value for the fit was 0.94.

Fig. 3
Fig. 3

a) Optical micrographs of emitted light (> 600 nm) from a droplet with radius ~17.4 μm imaged in the x-y plane when illuminated (i) by a low-power (100 mW) continuous-wave green laser with energy below lasing threshold, and (ii) by a pulsed green laser (0.24 mJ/pulse) with energy above lasing threshold. The dotted line in (a)(i) shows the outline of the drop. (b) shows a rendering image of a spherical micro-cavity and the cross-section of a WGM energy density profile (p = 1, m = l = 238), generated using finite element method (FEM) simulations. The radius of the cavity simulated was 17.352 μm. The index of the cavity was 1.54, and that in the surroundings was 1.33. (c) Absorption (solid line) and fluorescence spectra (dashed line) from rhodamine 640 perchlorate in benzyl alcohol. (d) shows the output intensity from the droplet integrated over wavelengths from 650 nm to 690 nm as a function of input pulse energy. The lasing threshold was about 2 μJ/pulse. The points in this inset were averages of 14 sets of data. The error bar equals to one standard deviation. (e) Emission spectrum of a single droplet containing 1-mM solution of rhodamine 640 in benzyl alcohol at input pulse energy of 0.24 mJ/pulse, corresponding to the image in (a)(ii). The spectrum is representative of emission from a single drop. The dashed line shows the fluorescence spectrum below lasing threshold, corresponding to the image in (a)(i). The calculated WGM positions for a spherical cavity with radius = 17.35 μm for transverse magnetic modes with p = 1 to 3 and m = 230 to 250 were aligned above the lasing spectrum. The linewidth of the modes was 0.16 nm, close to the spectral resolution of the spectrometer (0.1 nm).

Fig. 4
Fig. 4

a) Lasing spectra from drops possessing different radius R. The baseline value of each spectrum indicates the radius of the drop. The resolution of the spectrometer was 0.3 nm. Each spectrum is representative of emission from a single drop. b) Free spectral range (FSR) as a function of drop radius.

Fig. 5
Fig. 5

(a) Schematic diagram showing the gain spectrum (red) and the out-coupling efficiency β (black) of light from the droplet cavity. β shifts to shorter wavelengths as the radius of the cavity R decreases. (b) Schematic diagram showing the gain spectrum (red) and V/λ 3 (black), where V is the optical mode volume of the cavity. V/λ 3 shifts to shorter wavelengths as R decreases. (c) shows a diagram of the output power from the droplet laser. Since the output power is proportional to the product of the gain spectrum, the mode volume, and the out-coupling efficiency, the emission peak shifts to shorter wavelengths as the radius of the cavity decreases. (d) shows the calculated output power envelopes for droplet cavities with R = 8.9 μm and R = 19.4 μm respectively. The shift in the peak output power from λpeak ~700 nm (for drops with R = 19.4 μm) to λpeak ~600 nm (for drops with R = 8.9 μm) was approximately equal to that observed in Fig. 4a.

Equations (7)

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β = Q r a d 1 Q t o t a l 1 = Q r a d 1 Q r a d 1 + Q a b s 1
P o ~ V ( R , λ ) λ 3 g ( λ ) β ( R , λ )
[ n 1 k R j l ( n 1 k R ) ] n 1 2 j l ( n 1 k R ) = [ n 2 k R h l ( n 2 k R ) ] n 2 2 h l ( n 2 k R )
[ n 1 k R j l ( n 1 k R ) ] j l ( n 1 k R ) = [ n 2 k R h l ( n 2 k R ) ] h l ( n 2 k R )
Q r a d = Re [ x ] 2 Im [ x ] = n 1 2 ( n 1 2 n 2 2 ) 1 / 2 Re [ x ] 2 n 2 2 exp [ 2 T ]
Q r a d x
λ 1 ( R , n 1 , n r , p , m ) = 1 2 π R n 1 [ m + 1 2 + 2 1 / 3 α ( p ) ( m + 1 2 ) 1 / 3 L ( n r 2 1 ) 1 / 2 + 3 10 2 2 / 3 α 2 ( p ) ( m + 1 2 ) 1 / 3                         2 1 / 3 L ( n r 2 2 3 L 2 ) α ( p ) ( m + 1 2 ) 2 / 3 ( n r 2 1 ) 3 / 2 ]

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