217 research outputs found
Scatterer induced mode splitting in poly(dimethylsiloxane) coated microresonators
We investigate scatterer induced mode splitting in a composite microtoroidal
resonator (Q ~ 10^6) fabricated by coating a silica microtoroid (Q ~ 10^7) with
a thin poly(dimethylsiloxane) layer. We show that the two split modes in both
coated and uncoated silica microtoroids respond in the same way to the changes
in the environmental temperature. This provides a self-referencing scheme which
is robust to temperature perturbations. Together with the versatile
functionalities of polymer materials, mode splitting in polymer and polymer
coated microresonators offers an attractive sensing platform that is robust to
thermal noise.Comment: 9 pages, 3 figures, 15 reference
Estimation of Purcell factor from mode-splitting spectra in an optical microcavity
We investigate scattering process in an ultra-high-Q optical microcavity
coupled to subwavelength scatterers by introducing "splitting quality" Qsp, a
dimensionless parameter defined as the ratio of the scatterer-induced mode
splitting to the total loss of the coupled system. A simple relation is
introduced to directly estimate the Purcell factor from single-shot measurement
of transmission spectrum of scatterer-coupled cavity. Experiments with
polystyrene (PS) and gold (Au) nanoparticles, Erbium ions and Influenza A
virions show that Purcell-factor-enhanced preferential funneling of scattering
into the cavity mode takes place regardless of the scatterer type.
Experimentally determined highest Qsp for single PS and Au nanoparticles are
9.4 and 16.19 corresponding to Purcell factors with lower bounds of 353 and
1049, respectively. The highest observed Qsp was 31.2 for an ensemble of Au
particles. These values are the highest Qsp and Purcell factors reported up to
date.Comment: 5 Pages, 4 Figures, 12 Reference
Nanoemulsion from Piper aduncum, Cymbopogon nardus, and Bacillus thuringiensis to Control Xanthomonas axonopodis pv. allii
The bacterial species Xanthomonas axonopodis pv allii (Xaa) is an important pathogen causing leaf blight in shallots. The use of botanical pesticides with nanoemulsion formulations has become a common alternative. This study aims to determine the characteristics and optimum concentration of the mixture of essential oil of Piper aduncum and fragrant Cymbopogon nardus waste. Nanoemulsion formulations are made using spontaneous emulsification methods. Besides, testing Bacillus thuringiensis strain MRSNR3.1 and its secondary metabolites toxicity against Xaa was carried out by the diffusion method using paper discs to determine the diameter of the inhibition zone. The results demonstrate that all four concentrations, 1%, 2.5%, 5%, and 7.5%, could control Xaa bacteria. A concentration of 1% is considered more optimal than the other three concentrations in bactericidal effects against Xaa, as manifested in the formed clear zone (diameter of 3.17 cm). Besides, Bacillus thuringiensis strain MRSNR3.1 and its secondary metabolites were also effective againstXaa after four days of incubation with inhibition zones of 3.04 ± 0.44and 2.21 ± 0.28, respectively. Hence, it is concluded that nanoemulsion at 1% concentration and Bacillus thuringiensis strain MRSNR3.1 have bactericidal properties that can be used to control Xa
Controlled Manipulation of Mode Splitting in an Optical Microcavity by Two Rayleigh Scatterers
We report controlled manipulation of mode splitting in an optical
microresonator coupled to two nanoprobes. It is demonstrated that, by
controlling the positions of the nanoprobes, the split modes can be tuned
simultaneously or individually and experience crossing or anti-crossing in
frequency and linewidth. A tunable transition between standing wave mode and
travelling wave mode is also observed. Underlying physics is discussed by
developing a two-scatterer model which can be extended to multiple scatterers.
Observed rich dynamics and tunability of split modes in a single microresonator
will find immediate applications in optical sensing, opto-mechanics, filters
and will provide a platform to study strong light-matter interactions in
two-mode cavities.Comment: 9 pages, 5 figures, 14 references. Major revision. Published version
in Optics Expres
Epithelial Migration and Non-adhesive Periderm Are Required for Digit Separation during Mammalian Development.
The fusion of digits or toes, syndactyly, can be part of complex syndromes, including van der Woude syndrome. A subset of van der Woude cases is caused by dominant-negative mutations in the epithelial transcription factor Grainyhead like-3 (GRHL3), and Grhl3-/-mice have soft-tissue syndactyly. Although impaired interdigital cell death of mesenchymal cells causes syndactyly in multiple genetic mutants, Grhl3-/- embryos had normal interdigital cell death, suggesting alternative mechanisms for syndactyly. We found that in digit separation, the overlying epidermis forms a migrating interdigital epithelial tongue (IET) when the epithelium invaginates to separate the digits. Normally, the non-adhesive surface periderm allows the IET to bifurcate as the digits separate. In contrast, in Grhl3-/- embryos, the IET moves normally between the digits but fails to bifurcate because of abnormal adhesion of the periderm. Our study identifies epidermal developmental processes required for digit separation
Demonstration of mode splitting in an optical microcavity in aqueous environment
Scatterer induced modal coupling and the consequent mode splitting in a
whispering gallery mode resonator is demonstrated in aqueous environment. The
rate of change in splitting as particles enter the resonator mode volume
strongly depends on the concentration of particle solution: The higher is the
concentration, the higher is the rate of change. Polystyrene nanoparticles of
radius 50nm with concentration as low as 5x10^(-6)wt% have been detected using
the mode splitting spectra. Observation of mode splitting in water paves the
way for constructing advanced resonator based sensors for measuring
nanoparticles and biomolecules in various environments.Comment: 8 pages, 4 figures, 21 Reference
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