Lanthanide-doped nanocrystals in high-Q microtoroids for stable on-chip white-light lasers

Abstract

The plentiful energy states of lanthanide ( Ln 3 + )-doped nanomaterials make them very promising for on-chip integrated white-light lasers. Despite the rapid progresses, the Ln 3 + -based white upconversion emissions are strongly restricted by their low upconversion quantum efficiency and the color stability. Herein, we combine the CaF 2 : Yb 35 Tm 1.5 Er 0.5 nanocrystals and the high- Q microtoroids, and experimentally demonstrate the chip-integrated stable white-light laser. By optimizing the sizes, density, and distributions of Ln 3 + -doped nanocrystals, the Q factors of Ln 3 + -doped microtoroids are maintained as high as 5 × 10 5 . The strong light matter interaction in high- Q microtoroids greatly enhances the upconversion emission and dramatically reduces the laser thresholds at 652 nm, 545 nm, and 475 nm to similarly low values ( 1.89 – 2.10 mJ cm − 2 ). Consequently, robust white-light microlaser has been experimentally achieved from a single microtoroid. This research has paved a solid step toward the chip-scale integrated broadband microlasers.

Preparation and Characterization of Uniform and Controlled Silica Encapsulating on Lithium Yttrium Fluoride-Based Upconversion Nanoparticles

“…Rare earths-doped upconversion nanocrystals (UCNPs) have attracted significant interest for their exceptional chemical stability, significant Stokes shifts, narrow emission bandwidths, and resistance to photobleaching and photo blinking, coupled with their minimal toxicity [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. These optical and chemical properties make them an important class of optical materials for biomedical studies [ 8 , 9 ], optical refrigeration for remote cooling [ 10 , 11 , 12 , 13 , 14 ], phosphor for display applications (such as LEDs) [ 15 , 16 ], and luminescent thermometers [ 4 , 17 , 18 ]. To optimally harness the unique advantages of UCNPs for bio applications and other quantum technologies such as optical lasing and laser refrigeration, significant efforts have been put into choosing and improving the host materials [ 19 ].…”

Nucleation and Growth of Bipyramidal Yb:LiYF4 Nanocrystals─Growing Up in a Hot Environment

“…Lanthanide-doped nanocrystals (NCs) are an important class of optical materials, with applications that range from upconversion − for e.g . medical studies, − optical refrigeration for remote cooling, − phosphors for lighting and display applications (especially in micro-LEDs where conventional phosphor particles are too large), , to nanoscopic luminescent thermometers − and nanoscintillators. − The origin of their versatility in uses and properties lies in the existence of suitable host materials that can be synthesized as NCs and the broad variety of optical transitions, as well as a long excited state lifetime, of the elements in the lanthanide series …”