INFRARED LUMINESCENCE DECAY AND GUIDED SPECTROSCOPY OF ER3-BEAM EPITAXY LAYERS( DOPED CAF2 MOLECULAR)

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. Excitat ions at 800 nm, 980 nm, and 1.48 mu m were used to obtain the decay of the I-4(13/2)-->I-4(15/2) luminescence at 1.54 mu m. The results have been compared with those reported for the Er3+ doped CaF2 bulk and co rrelated with the low temperature luminescence study of these layers i n a back-scattering configuration. The I-4(13/2) level lifetime was fo und to be almost constant (similar to 11 ms) for Er3+ concentrations u p 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. (C ) 1998 American Institute of Physics.