High pressure tuning of whispering gallery mode resonances in a neodymium doped glass microsphere (original) (raw)
Related papers
Pressure tuning of whispering gallery mode resonators
Journal of the Optical Society of America B, 2007
The effect of hydrostatic pressure on solid and hollow microsphere optical resonators was investigated. The primary goal was to explore the feasibility of a micro-optical pressure sensor based on whispering gallery modes (WGMs) and to quantify the deleterious effect of environmental pressure changes on other WGM-based sensors. Expressions were developed for WGM shifts due to changes in hydrostatic pressure of the environment surrounding the spherical resonators. These expressions were validated through experiments in which the pressure-induced WGM shifts of hollow polymethyl methacrylate microspheres were monitored. The effect of atmospheric pressure variations on silica resonators is negligible, but hydrostatic pressure may be effective in the optical tuning of hollow polymer spheres.
Optics Communications, 2017
In this work a refractometric air pressure sensing platform based on spherical whispering-gallery mode microresonators is presented and analyzed. The sensitivity of this sensing approach is characterized by measuring the whispering-gallery mode spectral shifts caused by a change of air refractive index produced by dynamic sinusoidal pressure variations that lie between extremes of ±1.8 kPa. A theoretical frame of work is developed to characterize the refractometric air pressure sensing platform by using the Ciddor equation for the refractive index of air, and a comparison is made against experimental results for the purpose of performance evaluation.
Whispering gallery modes in a glass microsphere as a function of temperature
Optics Express, 2011
Microspheres of Nd 3+ doped barium titano silicate glass were prepared and the whispering gallery mode resonances were observed in a modified confocal microscope. A bulk sample of the same glass was calibrated as temperature sensor by the fluorescence intensity ratio technique. After that, the microsphere was heated by laser irradiation process technique in the microscope and the surface temperature was estimated using the fluorescence intensity ratio. This temperature is correlated with the displacement of the whispering gallery mode peaks, showing an average red-shift of 10 pm/K in a wide range of surface temperatures varying from 300 K to 950K. The limit of resolution in temperature was estimated for the fluorescence intensity ratio and the whispering gallery mode displacement, showing an improvement of an order of magnitude for the second method.
Effects of uniaxial pressure on polar whispering gallery modes in microspheres
Journal of Applied Physics, 2013
We investigate the detuning of whispering gallery modes (WGMs) in solid polystyrene microspheres (PM) as a function of axisymmetric stress applied to two antipodal points of the microsphere we call poles. We specifically investigate WGMs passing close to these poles, so-called polar WGMs. The applied uniaxial pressure reduces the geometrical circumference of the PM but also increases locally the refractive index at the flattened poles. Our experiments show that the WGMs shift to higher frequencies with increasing pressure and that the magnitude of the strain-induced shift depends on the radial mode number n. Furthermore an energy splitting between azimuthal modes linearly increasing with the pressure is observed. A theoretical model based on a classical ray optics approach is presented which reproduces the main results of our experimental observations. V
Spherical whispering‐gallery‐mode microresonators
Laser & Photonics …, 2010
Whispering-gallery modes (WGM) on a spherical surface were first described by Lord Rayleigh at the beginning of the last century, but only after the invention of laser did they start to have some scientific relevance and only during the last two decades there has been a substantial move towards real devices and practical applications. WGM resonators have peculiar properties, the most notable being the potential of having an ultrahigh quality factor Q, which makes them very appealing both as laser cavities and as extremely sensitive sensors. Among the different types of WGM resonators, the microspherical ones represent a very important category, due to their simplicity, easy fabrication, and very high quality. In this review we provide a description of their fundamental properties and we summarize recent works on their application as filters, sensors and lasers.
Whispering gallery mode microresonators: Fundamentals and applications
Confinement of light into small volumes has become an essential requirement for photonic devices; examples of this trend are provided by optical fibers, integrated optical circuits, semiconductor lasers, and photonic crystals. Optical dielectric resonators supporting Whispering Gallery Modes (WGMs) represent another class of cavity devices with exceptional properties, like extremely small mode volume, very high power density, and very narrow spectral linewidth. WGMs are now known since more than 100 years, after the papers published by John William Strutt (Lord Rayleigh), but their importance as unique tools to study nonlinear optical phenomena or quantum electrodynamics, and for application to very lowthreshold microlasers as well as very sensitive microsensors, has been recognized only in recent years. This paper presents a review of the field of WGM resonators, which exist in several geometrical structures like cylindrical optical fibers, microspheres, microfiber coils, microdisks, microtoroids, photonic crystal cavities, etc. up to the most exotic structures, such as bottle and bubble microresonators. For the sake of simplicity, the fundaments of WGM propagation and most of the applications will be described only with reference to the most common structure, i.e. microspherical resonators.
Photoluminescence and lasing in whispering gallery mode glass microspherical resonators
Journal of Luminescence, 2016
We report experimental results regarding the development of Er 3 þ-doped glass microspherical cavities for the fabrication of compact sources at 1.55 μm. We investigate several different approaches in order to fabricate the microspheres including direct melting of Er 3 þ-doped glass powders, synthesis of Er 3 þdoped monolithic microspheres by drawing Er 3 þ-doped glass, and coating of silica microspheres with an Er 3 þ-doped sol-gel layer. Details of the different fabrication processes are presented together with the photoluminescence characterization in free space configuration of the microspheres and of the glass precursor. We have analyzed the photoluminescence spectra of the whispering gallery modes of the microspheres excited using evanescent coupling and we demonstrate tunable laser action in a wide range of wavelengths around 1.55 μm. As much as 90 μW of laser output power was measured in Er 3 þdoped glass microspheres.
Journal of Applied Physics, 2010
A simple plane wave, ray-tracing approach was used to derive approximate equations for the dielectric microsphere whispering gallery mode ͑WGM͒ resonant wavenumber and quality factor, as dependent on the surrounding medium's refractive index. These equations are then used to determine the feasibility of a micro-optical sensor for species concentration. Results indicate that the WGMs are not sensitive enough to refractive index changes in the case of gas media. However, they can be sufficiently sensitive for measurements in liquids. Experiments were carried out to validate the analysis and to provide an assessment of this sensor concept.
Measurement of hydrostatic pressure using a hollow bottle microresonator
Journal of Physics: Conference Series
In this paper, we report the experimental results of the design and manufacture of a device in the form of a hollow bottle manufactured from a polymer for the measurement of hydrostatic pressure of microfluids in microcavities. The fabricated device bases its operation on the optical resonances of a capillary optical microresonator that couples the light coming from the evanescent field of an optical fiber taper with a central diameter in the range of 3-ȝP, exciting the resonant optical modes WGMs inside the cavity. The microcavity was manufactured using a heating-pressurization technique by a system built to measure which allowed reaching a minimum wall thickness in the central region of the order RI ȝP ZLWK D VHQVLWivity of the order of 0.5567 nm/bar.