Fiber-taper coupling to Whispering-Gallery modes of fluidic resonators embedded in a liquid medium.

We demonstrate efficient coupling to the optical Whispering- Gallery (WG) modes of a fluidic resonator consisting of a droplet embedded in a liquid medium. Unlike previous experiments the droplet is not levitated in an optical or electrostatic trap and free space coupling is replaced by phase-matched, waveguide coupling using a fiber-taper. We have observed critical coupling to fundamental WG modes of a 600 mum diameter water droplet at 980 nm. The experimental challenges towards making, stabilizing and coupling to the droplet resonators are addressed in this paper.

[1]  G. M. Hale,et al.  Optical Constants of Water in the 200-nm to 200-microm Wavelength Region. , 1973, Applied optics.

[2]  M. Schlossman,et al.  X-ray reflectivity study of the water-hexane interface , 1999 .

[3]  R. Chang,et al.  Laser emission from individual droplets at wavelengths corresponding to morphology-dependent resonances. , 1984, Optics letters.

[4]  Vladimir S. Ilchenko,et al.  Narrow-line-width diode laser with a high-Q microsphere resonator , 1998 .

[5]  Parallel-plate ion trap useful for optical studies of microparticles , 2004 .

[6]  Cai,et al.  Observation of critical coupling in a fiber taper to a silica-microsphere whispering-gallery mode system , 2000, Physical review letters.

[7]  J. Michael Ramsey,et al.  Detection of single Rhodamine 6G molecules in levitated microdroplets , 1993 .

[8]  Jonathan P. Reid,et al.  Cavity Enhanced Droplet Spectroscopy: Principles, Perspectives and Prospects , 2004 .

[9]  T. J. Kippenberg,et al.  Ultra-high-Q toroid microcavity on a chip , 2003, Nature.

[10]  R L Byer,et al.  High-resolution spectroscopy of whispering gallery modes in large dielectric spheres. , 1991, Optics letters.

[11]  Sigurd Wagner,et al.  Thermocapillary actuation of droplets on chemically patterned surfaces by programmable microheater arrays , 2003 .

[12]  R. Chang,et al.  Coherent Raman mixing and coherent anti-Stokes Raman scattering from individual micrometer-size droplets. , 1985, Optics letters.

[13]  Jonathan P. Reid,et al.  Control and characterisation of a single aerosol droplet in a single-beam gradient-force optical trap , 2004 .

[14]  Arthur Ashkin,et al.  Observation of Resonances in the Radiation Pressure on Dielectric Spheres , 1977 .

[15]  Sigurd Wagner,et al.  Microfluidic detection and analysis by integration of thermocapillary actuation with a thin-film optical waveguide , 2005 .

[16]  George M. Whitesides,et al.  Integrated fluorescent light source for optofluidic applications , 2005 .

[17]  Andrea M. Armani,et al.  Heavy water detection using ultra-high-Q microcavities. , 2006 .

[18]  Demetri Psaltis,et al.  A microfluidic 2×2 optical switch , 2004 .

[19]  Andrea M Armani,et al.  Heavy water detection using ultra-high-Q microcavities. , 2006, Optics letters.

[20]  J Johansson,et al.  Levitated droplet dye laser. , 2006, Optics express.

[21]  Brent E. Little,et al.  Analytic theory of coupling from tapered fibers and half-blocks into microsphere resonators , 1999 .

[22]  George M Whitesides,et al.  A low-threshold, high-efficiency microfluidic waveguide laser. , 2005, Journal of the American Chemical Society.

[23]  J. Baret,et al.  Electrowetting: from basics to applications , 2005 .

[24]  M. Gijs,et al.  A PMMA valveless micropump using electromagnetic actuation , 2005 .

[25]  George M. Whitesides,et al.  Diffusion-controlled optical elements for optofluidics , 2005 .

[26]  S. Arnold,et al.  Shift of whispering-gallery modes in microspheres by protein adsorption. , 2003, Optics letters.

[27]  D. Psaltis,et al.  Developing optofluidic technology through the fusion of microfluidics and optics , 2006, Nature.