Crystal growth, spectra properties, and 2-μm laser performance of a novel “mixed” Tm3+-doped CaY0.65Gd0.35AlO4 crystal

Abstract

A novel Tm3+: CaY0.65Gd0.35AlO4 (Tm3+: CYGA) disordered crystal was successfully grown for the first time, to the best of our knowledge, using the Czochralski method. The optical properties and laser performance were investigated in details. Owing to the addition of Gd3+ ions to the Tm3+: CYA crystal, the Tm3+: CYGA crystal possesses a wider Tm3+ absorption and emission spectra compared with those of the Tm3+: CYA and Tm3+: CGA crystals. In particular, the full width at half-maximum (FWHM) of the emission spectra at approximately 2 µm for the Tm3+: CYGA crystal was 221.3 nm, which is larger than those of the Tm3+: CYA (200 nm) and Tm3+: CGA (151 nm) crystals. Furthermore, an efficient laser operation of the Tm3+: CYGA crystal at 1974 nm was achieved for the first time, with a slope efficiency of up to 31.5 %, corresponding to a maximum output power of 810 mW. The results show that Tm3+: CYGA disordered crystals have the potential to be applied in ∼ 2-μm broadband tunable lasers and ultra-short pulse lasers.