Nd : Y2O3 single-crystal fiber laser: Room-temperature cw operation at 1.07- and 1.35-μm wavelength

Abstract

Single-crystal fibers have been grown from high-purity 1.5 wt% Nd 2O3 : Y2O3 powder mixtures, and short lengths of the fiber in dielectric mirror resonators have been evaluated as lasers at both 1.07- and 1.35-μm wavelength. The laser transition cross sections were approximately equal at the two wavelengths, and they were about two-thirds the cross section of Nd : YAG at 1.31 μm. The fluorescence lifetime of the laser samples was 340 μsec. Loss in the material was approximately 3% per cm. The absorption spectrum from 0.7 to 1.0 μm and fluorescence spectra for the 4F3/2→4I9/2, 4F 3/2→4I11/2, and 4F3/2→4I 13/2 manifolds of Nd3+ in Y2O3, taken with fiber samples, are reproduced in detail. The resultant energy levels are given. With a Kr laser operating at 0.7525 μm as the end pump, minimum observed laser threshold was 0.57 mW absorbed pump power for a 100-μm-diam 2.5-mm-long fiber operating cw in room-temperature air at 1.07 μm. The lasers operated in one or two transverse modes and had active linewidths of approximately 2 Å.