Photoluminescence of Bi4Si3O12:Er3+ crystal excited in the commercial laser diode emission region

The luminescence of Er3+ ions in Bi4Si3O12 has been investigated in the excitation spectral range corresponding to diode pumping (760–840 nm) under continuous wave laser excitation. In addition to the one photon infrared emission (4I11/2 → 4I15/2), up-converted luminescence in the green (2H11/2,4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) spectral regions are observed under excitation within the 4I9/2 state (795 nm). From a detailed analysis of cw experimental data it is inferred that such up-converted emissions can be attributed to a combination of excited state absorption and energy transfer up-conversion processes.