Near-infrared diode-pumped white-light emission from erbium-doped calcium fluoride crystal

Abstract

CaF 2 is a cubic material and Erbium enters the lattice in triply ionized state. Erbium occupies Ca sites in the material. Defects occur in the material because a trivalent dopant ion replaces a divalent host ion. Er 3+ occupies several different sites. Absorption spectrum of Er 3+ -doped CaF 2 revealed absorption peaks at 255, 365, 379, 407, 441, 449, 487, 522, 539, 652 and 798 nm. When the sample was excited with an 800 nm near-infrared laser it revealed emissions at 390, 415, 462, 555, 665 and 790 nm. The absorption and emission peaks are identified with Er 3+ spectral transitions. The sample color appears to be either white or green under near-infrared laser excitation. Emission color was found to be dependent on the pump laser wavelength used and laser power. Excitation spectral recordings were made by tuning the pump laser wavelength. The sample emission appears to be white under near-infrared excitation as well as violet laser excitation. Excited state lifetimes are measured to analyze the data. Our studies indicate that this sample is useful in solid state lighting applications.