Schematic of experimental setup.
Fine spectrum of the green emissions from a ZBNA microsphere. An estimate of the sphere’s -factor can be obtained by measuring the width of the fine peaks.
Intensity of the 550 nm output vs estimated pump power coupled into the microsphere. The solid line is a linear fit. Inset (a): SEM image of a ZBNA microsphere. Inset (b): optical image of ZBNA microsphere showing multiple scattering points. Inset (c): optical image of a ZBNA microsphere (right) and corresponding intensity map of the image (left), showing the WGM ring around the sphere’s circumference. The two large bright points are due to scattering from internal or surface defects
(a) Launched, scattered and transmitted pump power from a sphere plotted as a function of time. The launched pump power has a curved shape due to the response of the electronic variable attenuator. As the launched pump power increases, pump/cavity resonant dips appear in the transmitted pump power, When the pump power is decreasing the same resonant dips appear again but at different pump powers and with a broadened line shape. The maximum launched pump power was and the maximum temperature recorded was 440 K. (b) Launched, scattered, and transmitted pump power from a sphere plotted as a function of time. The maximum temperature recorded was 566 K giving an estimated mode shift of 2.2 nm.
(a) Launched pump power and scattered green emission from a sphere as a function of time. The multiple jumps in the green intensity correspond to multiple, coincidental pump/cavity resonances. (b) Launched pump power and scattered green emission from a sphere as a function of time. Only a single pump/cavity resonance was encountered over the whole pump power range. The maximum pump power launched into the tapered fiber, in both cases, was 50 mW.
Scattered green emission (black curve) and pump power (red curve) vs time. Points 1–4 indicate the switching states for the fluorescence.
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