Infrared luminescence decay and guided spectroscopy of Er3+ doped CaF2 molecular beam epitaxy layers

Abstract

The decay of infrared luminescence in Er3+-doped CaF2 layers grown by molecular beam epitaxy (MBE) on CaF2 substrates has been studied as a function of the Er3+ concentration in the 0.05–35 mol % range. Excitations at 800 nm, 980 nm, and 1.48 μm were used to obtain the decay of the I13/24→4I15/2 luminescence at 1.54 μm. The results have been compared with those reported for the Er3+ doped CaF2 bulk and correlated with the low temperature luminescence study of these layers in a back-scattering configuration. The I13/24 level lifetime was found to be almost constant (∼11 ms) for Er3+ concentrations up to 5 mol %. At higher concentrations, the lifetime decreases due to energy transfer, but remains longer than the lifetime measured in the bulk because of the different formation of aggregated centers induced by the MBE growth conditions. The strong increase of the luminescence intensity observed from 10 to 35 mol % Er3+ concentrations despite the decrease of the lifetime is discussed. Finally, end-fire coupling of a diode laser at 977 nm and propagation through 15 mm long waveguides have been observed for moderate Er3+ concentrations (6 mol %). Guided and side IR luminescence spectra have been obtained and contrasted.

Spectroscopic properties of Er3+/Yb3+co-doped 50SiO2–20Al2O3–30CaF2glass and glass ceramics

“…The same material as thin films deposited on Si substrates has also been studied [18,19]. CaF 2 :Er 3+ optical waveguides grown by molecular beam epitaxy have recently been demonstrated [20][21][22]. Furthermore, crystalline CaF 2 is highly transparent from 0.13 to 9.5 µm and gives a better matching of refractive index with the aluminosilicate glassy host.…”