Growth and spectroscopic properties investigation of Er-doped BGSO single crystal: A potential gain medium for eye-safe laser

Erbium-doped crystals are well-suited for eye-safe solid-state laser systems around 1.5 μm. Broadband and high-gain Er-doped laser crystals can achieve high-power tunable laser output, which plays a great role in promoting commercial eye-safe laser research. Herein, the 2 at% Er-doped bismuth germanium silicate (BGSO) laser crystal is successfully grown by the vertical Bridgman method. The X-ray Rietveld refinement was used to obtain the structural parameters. The spectroscopic parameters of Er ions in BGSO crystal are calculated and analyzed with Judd-Ofelt theory. Furthermore, the broadband luminescence is observed in the wavelength range of 1450–1600 nm. The stimulated emission cross-section is calculated around 1500 nm, which largest value is 5.31 × 10−20 cm2 at 1543 nm. Meanwhile, the luminous efficiency of BGSO crystal in the eye-safe band is further characterized and explored by studying the energy transfer process and anomalous thermal quenching in the 550 nm and 660 nm bands. All results indicate that the Er: BGSO crystal is a promising broadband eye-safe laser material.