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Active and passive optical waveguides are fundamental elements in modern telecommunications systems. A great number of optical crystals and glasses were identified and are used as good optoelectronic materials. However, fabrication of waveguides in some of those materials remains still a challenging task due to their susceptibility to mechanical or chemical damages during processing. Ion beam has...
SU-8 based polymeric microbottle resonators are fabricated by an innovative self-assembled process. The dispensing of a precise quantity of SU-8 on a fiber stem combined with UV cross-linking process allows the development of high quality microbottle resonators. Geometrical size, in terms of bottle radii and neck-to-neck distance, can be widely modified by controlling the dispensed resist volume....
We implement a mathematical model able to predict the amplitude variation of the optical field inside a coupled high-Q resonator as a function of the scanning wavelength. Similarly to a Fabry-Perot cavity with its two highly reflecting mirrors, the resonator has two fiber based tap couplers. By fitting experimental data with this model, it is possible to determine the physical characteristics of the...
In the last two decades, a remarkable progress has occurred in the development of biosensor photonic devices and their application in areas ranging from environmental monitoring to food safety, medical diagnostics, drug screening. As an example, recent developments have greatly improved the sensitivity of optical sensors based on metal nanoparticle arrays and single nanoparticles; plasmonic nanosensors...
In this paper, a brief analysis is presented of two critical issues for the full exploitation of the unique properties of microresonators based on Whispering Gallery Modes (WGM), namely the coupling of light into/out-of a WGM resonator (WGMR), and the integration of the WGMR with the light injection system and with other sub-systems (e.g. with microfluidics, in the case of biochemical sensors). The...
High-Q whispering gallery mode resonators (WGMs) made both in glasses or crystals attract growing interest not only for the investigation of fundamental processes but also for the implementation of advanced photonics devices and biological sensors [1]. For practical applications of WGM resonators the crucial issue is the implementation of an efficient and robust coupling scheme. Fiber taper based...
Bismuth germanate crystal (BGO) has gained considerable attention due to its very attractive physical and optical properties. Thanks to its very good radiation length, short decay time, emission efficiency and response linearity, it is widely used as scintillator material for radiation detectors in high-energy physics and in medical diagnostic systems such as PET (positron emission tomography) [1]...
Er3+-acticated silica-hafnia glass-ceramic waveguides were fabricated by bottom-up and top-down approaches. The pros and cons of the procedures in terms of optical, spectroscopic and structural properties are reported, in particular regarding attenuation coefficient, NIR emission, and local environment for the rare-earth ions. The results confirm the significance of SiO2-HfO2 glass ceramic waveguides...
Sol-gel route is employed to prepare three nanostructured systems, namely core-shell Er3+-activated silica particles, Er3+-activated silica inverse opal; and spherical microresonators coated by Er3+-activated silica-hafnia film. Fabrication protocol, morphology, and spectroscopic assessment are presented. All the structures exhibit high compositional homogeneity leading to a significant 4I13/2 luminescence...
In this paper, we present a short review of the activity performed in developing glass-based photonic structures on the nano and micro scale, based on the sol-gel techniques and activated by rare earth ions. Optical and spectroscopic assessment of glass ceramic waveguides is discussed. Luminescence enhancement is demonstrated. Refractive index modulation upon UV exposure is measured in SiO2-SnO2 film...
In this paper we propose a method to overcome one the major fundamental limitation of silica spherical micro resonators for frequency reference, i.e. temperature stabilization, by coating the micro resonator with an appropriate material through the use of an innovative sol-gel method. We experimentally characterize the thermal drift of a resonant frequency of a silica microsphere coated by a Polymethyl...
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