Cr:Gd2SrAl2O7: A potential tunable laser crystal with high energy storage capacity

Abstract

The Cr3+ doped Gd2SrAl2O7 (Cr:GSAO) crystal with tunable light emission has been successfully grown by the Czochralski method for the first time. The Cr:GSAO crystal shows strong absorption on the visible light with an absorption cross-section of 0.53 × 10−19 cm2 at 580 nm for σ-polarization. The crystal field analysis results reveal that Cr3+ ions are accommodated at more than one type of lattice site in GSAO, one with a strong crystal field and the others with an intermediate crystal field. The crystal features long-lived and tunable luminescence. The room temperature luminescence spectrum of Cr:GSAO crystal ranging from 700 nm to 1000 nm is composed of a sharp emission peak and a broad band, which are assigned to the zero-phonon emission and the phonon assisted transitions from 4T2–4A2 of Cr3+. The luminescence lifetime of the Cr:GSAO crystal is 2.82 ms. This indicates that the Cr:GSAO crystal has a potentially good laser performance with excellent energy storage capacity. Our work demonstrates that the Cr:GSAO crystal is a promising candidate for tunable laser gain media.