Very low threshold lasing in Er ³⁺ dopedZBLAN microsphere

Erbium-implanted high-Qsilica toroidal microcavity laser on a silicon chip

“…(9) for the population inversion, cavity loss ␣ s passive at the signal wavelength is the only variable that can be controlled (after fabrication) by changing the waveguide loading of the cavity. This passive cavity signal loss ␣ s passive can be expressed using the loaded Q factor as in (10). In the case of weak coupling between the resonator and the waveguide, the decomposition of the loaded Q factor for the passive (i.e., without the effects of erbium ions) microcavity is given by the following simple form:…”

“…Cavity quality factors (Q factors) as high as 8 ϫ 10 9 [1,2], along with small mode volumes, have been essential driving forces for fundamental research areas such as cavity quantum electrodynamics, nonlinear optics, biosensing, and microscale lasers [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The first studied ultrahigh-Q optical microcavities were liquid microdroplets.…”

“…These include whispering-gallery-type microsphere lasers doped with neodymium, erbium, and ytterbium-sensitized erbium [8][9][10][11][12][13][14][15]. For the case of a neodymium-doped microsphere laser demonstrated by Sandoghdar et al [8], the (absorbed) threshold power was as low as 200 nW.…”

Demonstration of a cw room temperature mid-IR microlaser

“…Whispering-gallery-mode (WGM) microlasers [1][2][3][4][5][6][7][8] show strong potential as compact high-performance narrow linewidth light sources for numerous photonic applications, including ultrasensitive molecular sensing and comb generation. Among these, optically pumped WGM microlasers [1][2][3][4][5][6] are particularly attractive and popular, largely because of their relative ease of fabrication (as opposed to their electrically pumped semiconductor counterparts [7,8], which require much more elaborate design and fabrication processes).…”

<title>Whispering gallery modes in glass microspheres made by simple technology</title>

“…This is essential for the usage of microresonators in the studies of the interaction of quantified electromagnetic fields with atoms, molecules or nanocrystals placed inside a resonating microsphere or on its surface. The applications of spherical glass resonators are related to low-threshold lasers [5], up-conversion lasers [6], bistable optical elements [7], filters and delay lines [8]. Most prospective for practice are resonators made of glass doped with rare-earth ions, but recently the interest to other dopants of high radiation efficiency, like CdSSe, has also arisen [9] .…”