High-concentration Er3+ ion singly doped GaTaO4 single crystal for promising all-solid-state green laser and solid-state lighting applications

Abstract

Exploring new visible laser crystals is of great significance to the development of diode pumped all-solid-state visible lasers and solid-state lighting. In this work, a high concentration (10 at%) Er³⁺ ion singly doped GdTaO₄ single crystal with high quality as a promising visible laser crystal was grown successfully by the Czochralski method. The structure of the crystal was determined to be a monoclinic structure with the space group C2/c by powder and single-crystal X-ray diffraction characterization techniques. The absorption and blue and violet light excited emission spectra of the crystal were obtained and analyzed. A strong emission band centered at 555 nm was observed under excitation at both 450 nm and 377 nm. The absorption cross-section at 450 nm and emission cross-section at 555 nm were calculated to be 4.60 × 10⁻²¹ and 4.57 × 10⁻²¹ cm², respectively, which are comparable to those of other promising InGaN diode pumped visible laser crystals doped with rare earth ions (Er³⁺, Dy³⁺ and Pr³⁺). Under 450 nm or 355 nm laser excitation, the crystal emits strong green fluorescence. A 380 nm LED chip pumped prototype device was fabricated using the crystal, which exhibited green light under the driving current. Besides, the green and red upconversion luminescence of Er³⁺ in the GdTaO₄ single crystal was found to be a two-photon process under the excitation of a 980 nm laser. All these results strongly recommend that the 10 at% Er³⁺ ion doped GdTaO₄ crystal is very promising for diode pumped green lasers and probably useful for solid-state lighting.