Measurement of point defect energetics in potassium dihydrogen phosphate (KDP). Final report

Abstract

Potassium dihydrogen phosphate (KDP) in the normal and deuterated form (KD*P) exhibits excellent electrooptical and nonlinear optical properties and is commonly used in frequency conversion applications. Frequency doubling (2 {omega}) of Nd:YAG or Nd:YLF laser fundamental output at 1.06 {micro}m produces visible radiation at 532 nm with relatively good conversion efficiency. Frequency tripling (3{omega}) and quadrupling (4{omega}) are also utilized for production of ultraviolet (uv) radiation at 355 and 266 nm, respectively. However in the latter case the conversion efficiency is relatively low, especially at high incident fluences ({approximately}2 GW/cm{sup 2}). A fundamental problem associated with high peak-power laser excitation of KDP is the production of transient optical absorption that inhibits conversion efficiency. The role of point defects on frequency conversion efficiency and optoelectronic device performance in KDP and its isomorphs is not fully understood. However, it is evident from the extant data that their existence, even in pure specimens, affects the overall performance of these technologically important materials, and that further research is required to elucidate their role. Accordingly, they have investigated the temperature-dependent optical absorption and radioluminescence (RL) of pure KDP as well as doped specimens: KDP:Fe, KDP:Cr, and KDP:Al.