113 research outputs found
Localization of light on a cone: theoretical evidence and experimental demonstration for an optical fiber
The classical motion at a conical surface is bounded at one (narrower) side
of the cone and unbounded at the other. However, it is shown here that a
dielectric cone with a small half-angle gamma can perform as a high Q-factor
optical microresonator which completely confines light. The theory of the
discovered localized conical states is in excellent agreement with experimental
data. It provides both a unique approach for extremely accurate local
characterization of optical fibers (which usually have gamma ~10^-5 or less)
and a new paradigm in the field of high Q-factor resonators
Trapping and unlimited delay of light pulses at microscale without distortion
A tunable bottle microresonator can trap an optical pulse of the given
spectral width, hold it as long as the material losses permit, and release
without distortion
Slow light microfluidics: a proposal
The resonant slow light structures created along a thin-walled optical
capillary by nanoscale deformation of its surface can perform comprehensive
simultaneous detection and manipulation of microfluidic components. This
concept is illustrated with a model of a 0.5 millimeter long 5 nm high
triangular bottle resonator created at a 50 micron radius silica capillary
containing floating microparticles. The developed theory shows that the
microparticle positions can be determined from the bottle resonator spectrum.
In addition, the microparticles can be driven and simultaneously positioned at
predetermined locations by the localized electromagnetic field created by the
optimized superposition of eigenstates of this resonator, thus, exhibiting a
multicomponent near field optical tweezers
Surface nanoscale axial photonics: Robust fabrication of high quality factor microresonators
Recently introduced Surface Nanoscale Axial Photonics (SNAP) makes it
possible to fabricate high Q-factor microresonators and other photonic
microdevices by dramatically small deformation of the optical fiber surface. To
become a practical and robust technology, the SNAP platform requires methods
enabling reproducible modification of the optical fiber radius at nanoscale. In
this Letter, we demonstrate super-accurate fabrication of high Q-factor
microresonators by nanoscale modification of the optical fiber radius and
refractive index using the CO2 laser and the UV excimer laser beam exposures.
The achieved fabrication accuracy is better than 2 angstroms in variation of
the effective fiber radius
Surface nanoscale axial photonics at a capillary fiber
We present the theory and first experimental demonstration, to the best of our knowledge, of a sensing platform based on surface nanoscale axial photonics (SNAP) at a capillary fiber. The platform explores optical whispering gallery modes, which circulate inside the wall of a capillary and slowly propagate along its axis. Due to the small thickness of the capillary wall, these modes are sensitive to spatial and temporal variations of the refractive index of the media adjacent to the internal capillary surface. In particular, the developed theory allows us to determine the internal effective radius variation of the capillary from the measured mode spectra. Experimentally, a SNAP resonator is created by local annealing of the capillary with a focused CO2 laser followed by internal etching with hydrofluoric acid. The comparison of the spectra of this resonator in the cases when it is empty and filled with water allows us to determine the internal surface nonuniformity introduced by etching. The results obtained pave the way for a novel advanced approach in sensing of media adjacent to the internal capillary surface and, in particular, in microfluidic sensing
Optical frequency combs generated mechanically
An elongated bottle microresonator with nanoscale parabolic effective radius variation can possess a series of dense equally spaced optical eigenfrequencies whose separation can match the eigenfrequency of its axially symmetric acoustic mode. It is shown that this acoustic mode can parametrically excite optical modes and give rise to a highly equidistant and moderately broadband optical frequency comb with the teeth spacing independent of the input laser power and the amplitude of mechanical vibrations
Tunable photonic elements at the surface of an optical fiber with piezoelectric core
Tunable photonic elements at the surface of an optical fiber with piezoelectric core are proposed and analyzed theoretically. These elements are based on whispering gallery modes whose propagation along the fiber is fully controlled by nanoscale variation of the effective fiber radius, which can be tuned by means of a piezoelectric actuator embedded into the core. The developed theory allows one to express the introduced effective radius variation through the shape of the actuator and the voltage applied to it. In particular, the designs of a miniature tunable optical delay line and a miniature tunable dispersion compensator are presented. The potential application of the suggested model to the design of a miniature optical buffer is also discussed
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