Mid-infrared fine-grained Er:Y2O3 laser ceramics fabricated by spark plasma sintering

Transparent Er-doped Y2O3 2 O 3 ceramics were fabricated using the spark plasma sintering (SPS) technique without any sintering additives to achieve fine-grained mid-infrared laser ceramics. The average grain size of ceramics was typically 300 nm and their in-line optical transmittance in the 2.7 mu m mid-infrared range reached approximately 99 % of the theoretical value. The fluorescence spectra and lifetimes confirmed that the ceramics fabricated using SPS exhibited emission characteristics nearly identical to those fabricated using other sintering techniques. Despite the numerous pores in the ceramics and considerably reduced transmittance at an excitation wavelength of 976 nm (approximately 90 % of the theoretical value), a successful laser oscillation at 2.7 mu m in the mid-infrared region was achieved. To the best of our knowledge, this is the first report on mid-infrared laser operation for fine-grained ceramics having grain sizes below 500 nm. We believe that this study will contribute to further improvements in the optical properties and development of fine-grained transparent ceramics as new laser materials, particularly non-cubic materials.