Strong localization and suppression of Anderson modes in an asymmetrical optical waveguide.

In this paper, transverse Anderson localization of light waves in a 3D random network is achieved inside an asymmetrical type optical waveguide, formed within a fused-silica fiber by capillary process. Scattering waveguide medium originates from naturally formed air inclusions and Ag nanoparticles in rhodamine dye doped-phenol solution. Multimode photon localization is controlled by changing the degree of the disorder in the optical waveguide to suppress unwanted extra modes and obtain only one targeted strongly localized single optical mode confinement at the desired emission wavelength of the dye molecules. Additionally, the fluorescence dynamics of the dye molecules coupled into the Anderson localized modes in the disordered optical media are analyzed through time resolved experiments based on a single photon counting technique. The radiative decay rate of the dye molecules is observed to be enhanced up to a factor of about 10.1 through coupling into the specific Anderson localized cavity within the optical waveguide, providing a milestone for investigation of transverse Anderson localization of light waves in 3D disordered media to manipulate light-matter interaction.

A hybrid photonic-plasmonic resonator based on a partially encapsulated 1D photonic crystal waveguide and a plasmonic nanoparticle.

In this paper, a hybrid photonic-plasmonic resonator is proposed. The device consists of a partially encapsulated 1D photonic crystal waveguide and a plasmonic nanoparticle to yield high radiation efficiency for integrated photonic platforms, owing to a high Q-factor and a small mode volume. The design of the resonator is accomplished in two consecutive steps: first of all, a partially encapsulated photonic crystal nanobeam with a robust mechanical stability and a high-Q factor is prepared; secondly, a plasmonic nanoparticle is placed on the surface of the nanobeam to interact the optical mode with the localized surface plasmons of the gold nanoparticle which is being present in the vicinity of the radiating dipole. Strongly enhanced electromagnetic field, regenerated through the optical mode field inside the hybrid resonator, enables to reduce the optical mode volume of the device and significantly enhance the Purcell factor.

Enhancement of the spontaneous emission rate of Rhodamine 6G molecules coupled into transverse Anderson localized modes in a wedge-type optical waveguide.

In this paper, the dynamics of the spontaneous emission rate of Rhodamine 6G dye molecules, coupled into disorder-induced optical cavities in a scattering medium, is investigated by a time-resolved spectroscopic technique. The system is a wedge-type wave-guiding system formed by a polymer with randomly positioned air inclusions. The scattering of light in the medium induces transverse Anderson localization, which gives rise to quasi-optical modes or Anderson-localized cavities. The presence of these modes strongly enhances the decay emission of the emitters. The waveguide is fabricated by a conventional fiber drawing technique inside a fused silica micro-rod. Localized optical modes are observed to appear in the form of sharp spectral resonance peaks at various frequencies throughout the photoluminescence spectrum of the dye molecules. The spontaneous emission rate of the molecules on resonance with the localized modes is measured to enhance by a factor of up to 6.8, which elucidates that the transverse Anderson localization enables an efficient way to alter the spontaneous emission rate of quantum emitters in an optically asymmetric simple wedge-type photonic waveguide, offering a moderate alternative to highly engineered sophisticated light-wave devices.

Scanning Acoustic Microscopy and Time-Resolved Fluorescence Spectroscopy for Characterization of Atherosclerotic Plaques.

Atherosclerotic plaques constitute the primary cause of heart attack and stroke. However, we still lack a clear identification of the plaques. Here, we evaluate the feasibility of scanning acoustic microscopy (SAM) and time-resolved fluorescence spectroscopy (TRFS) in atherosclerotic plaque characterization. We perform dual-modality microscopic imaging of the human carotid atherosclerotic plaques. We first show that the acoustic impedance values are statistically higher in calcified regions compared with the collagen-rich areas. We then use CdTe/CdS quantum dots for imaging the atherosclerotic plaques by TRFS and show that fluorescence lifetime values of the quantum dots in collagen-rich areas are notably different from the ones in calcified areas. In summary, both modalities are successful in differentiating the calcified regions from the collagen-rich areas within the plaques indicating that these techniques are confirmatory and may be combined to characterize atherosclerotic plaques in the future.

Four-core optical fiber as a calorimetric gauge.

A four-core optical fiber is demonstrated as a calorimetric gauge for investigation of one-dimensional heat transfer measurements. Transient heat pulses from a Nd:YAG laser of 600 ms duration with a repetition rate of the order of 10 s are delivered onto the cleaved distal end face of the four-core fiber, aiming at one of the single cores only, which cause an optical path length difference between four guiding cores due to the temperature-induced change in the index of refraction and physical length of the targeted fiber core of concern. This results in a shift in the fringe pattern, which is operated in the reflection scheme. A phase shift of 0.43±0.015 rad is measured with a CMOS camera for 40 mW pulses. The thermal heat diffusion length in the selected fiber core is determined to be 2.8 mm, which contains 10.9±0.38 kJ/m2s heat, causing a temperature rise of 1.43±0.05 K.