Introduction to Spectroscopy of Cr ⁴⁺ :YAG Transparent Ceramics

ABSTRACT This paper focuses on the spectroscopic properties of Cr 4+ :YAG transparent ceramic. Absorption, excitation, and emission spectra were measured over a temperature range from 5 to 300 K. Low‐temperature absorption spectra reveal sharp and narrow lines corresponding to partially allowed transitions from the ground state to the crystal‐field splitting components of the 4 T 2 energy level. The shape of the excitation spectra was found to be independent of the monitored emission wavelength, indicating that Cr 4+ emission originates from the lowest excited state. Low temperature emission spectra exhibit a sharp and narrow ZPL, accompanied by the vibronic sidebands extending up to ∼2000 cm −1 . Both absorption and emission spectra of the lowest excited state at low temperature consist of a doublet, with a splitting of 28 cm −1 . The temperature dependence of the spectroscopic parameters of this doublet is reported. Based on the obtained results, possible explanations of their origin are proposed.