Cr 3+ ion doped YAG (Cr 3+ ∶YAG) layers grown by LPE is a newly developed single crystalline cathodoluminescent phosphor with a broad emission in red band. The maximum intensity of Cr 3+ emission in YAG is at λ max ≈689 nm, 709 nm with a color point of x=0 6551, y=0 2949, which is of the same chromaticity with a red emission of λ=638 nm. The abundant red components of Cr 3+ emission in the vicinity of λ≈700 nm give a deep impression, this made Cr 3+ ∶YAG of great value in the development of high resolution α Si∶H liquid crystal light valve projection display.