Solar🌄Garden" #Microlaser detects individual molecule...." Everyone in #photonics is probably doing this now but it seems such a simple yet clever idea. #RabbitHole of the afternoon - and well enough explained for a non-specialist to follow.
"The resonators we used in this study were microspheres with diameters ranging from 70 to 110 μm, ⭐fabricated by⭐melting ⭐the tips of⭐optical⭐fibres⭐ ... dip coated with two thin layers of Yb3+-doped sol .... The resonators exhibited Q factors of 105−106 at the excitation wavelength band.
A 972-nm laser used to excite the gain medium via a tapered fibre (TF) coupled to the microlaser (Fig. 1)⬇️ , with emission typically observed between 1,030 nm and 1,100 nm. All the experiments were conducted in aqueous environments, and ytterbium was selected as it particularly provides high gain efficiency when the resonator is operated when immersed in water and emitting at a wavelength with excellent water transmission. Due to its high gain efficiency in water, sub-milliwatt excitation and lasing are enabled...."
(Fig. 1)⬇️
https://www.nature.com/articles/s41566-026-01882-7/figures/1