High pressure tuning of whispering gallery mode resonances in a neodymium-doped glass microsphere

Abstract

The effects of pressure on the behavior of optical microspherical resonators, prepared from Nd 3 doped, barium titanium silicate glass, have been studied up to 5 GPa inside a diamond anvil cell using silicone oil as the hydrostatic transmission medium and ruby emission lines as the pressure gauge. The optical resonances, known as whispering gallery modes, were observed within the broad emission band of the Nd 3 ions, and the resonances were identified as a function of pressure. By means of simulations, it was found that the average wavelength position of both transverse electric and magnetic modes depended on the radius and refractive index of the sphere, but not on the refractive index of the pressure transmitting medium under the experimental conditions. This was used to define the average sensitivity of the resonant modes with the pressure. Therefore, a value of 6.5 × 10 −4 GPa −1 has been obtained for this sensitivity, which is higher than the value for ruby, the most conventional pressure sensor.

Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications

“…Strain tuning of microresonators is an effective, fast and stable tuning method and has been reported previously for passive glass microcavities 19 20 22 24 25 , as well as for passive and doped polymer cavities 21 56 57 . Its use for tuning doped glass resonators has been limited 26 58 . Strain tuning of an erbium-doped microbottle laser was reported by Pöllinger et al .…”

“…Tuning a micron-scale whispering gallery resonator in a fashion that does not add to the footprint of the device or require complicated fabrication is a nontrivial task. The main approaches so far include the use of external heaters 17 18 , application of stress/strain via an external clamp 19 20 21 22 , pressure tuning 23 24 25 26 27 , electric field tuning 28 , chemical etching 29 30 , on-chip resistance heating 31 32 , photorefractive tuning 33 and thermo-optic tuning 34 35 36 . Each of these methods has its own distinct advantages and disadvantages and the choice of method depends ultimately on the final application.…”

Whispering Gallery Mode Devices for Sensing and Biosensing

“…The first point is the wavelength shift resolution, R. If one is trying to find the central wavelength, λ 0 , of a single WGM, one often uses either centroid [55] or curve-fitting [56] methods. The centroid method simply finds the center-of-mass of the resonance profile, whereas curve fitting requires an adequate model (e.g., a Lorentzian) and initial parameters.…”

Temperature dependence of the whispering gallery modes obtained in a glass microsphere codoped with Er3+–Yb3+ ions

“…The dependence of the WGM with temperature in the emission band of ytterbium will be analysed. WGM are very sensitive to the variation of the refractive index of the microsphere and also to changes in the dimensions of the cavity, which are both caused by a shift in temperature [16]. The sensitivity with temperature of this method is compared with that of the FIR technique applied to the thermalized bands of Er 3+ ions.…”