Laser damage formation in KTiOPO4 and KTiOAsO4 crystals: Grey tracks

Abstract

The grey track effect in KTiOPO4 and KTiOAsO4 is shown to be related to the presence of Ti+3. The susceptibility to grey track formation was maximum in crystals grown from tungsten-based solvents. The data shows that no clear correlations exist between grey track susceptibility and either ionic conductivity or crystal-growth temperature. The similarity of grey tracks with photorefractive damage in LiNbO3 suggests the effect can be eliminated by stabilization of Ti+3 using charge compensation.

> 6-W continuous-wave, efficient, low-noise, diode-pumped intracavity-doubled Nd:YAG laser for pumping Ti: Sapphire lasers

“…is low and gray tracking as a typical crystal defect for KTP is less likely to occur [5]. In an actual experiment, the conversion efficiency obtained is much higher and the green output is more stable than those in other KTPs flux-grown from several makers.…”

DEPSCOR-95: Development of Nonlinear Optical Materials for Optical Parametric Oscillator and Frequency Conversion Applications in the Near- and Mid-Infrared

“…24 ' 26 It has many excellent optical and physical properties and is presently used in second harmonic generation (SHG) and optical parametric oscillator (OPO) devices. However, laser-induced damage [27][28][29][30][31][32] continues to be a problem in some of these applications. Gray tracks, regions of increased visible absorption, may form along the beam path in the bulk of a KTP crystal when the pump laser operates at high peak power.…”

Growth, structural, thermal, electrical and nonlinear optical properties of Yb3+ doped KTiOPO4

“…The transition metal ions doping increases the ionic conductivity that creates damage on the surface during the frequency conversion at low temperature ( $ 303 K) [13]. The Ti 3 þ and O 2 À vacancies are the reason for gray coloration in the crystal during the laser irradiation [14][15][16]. The presence of Ti 3 þ in the crystal increases the conductivity and decreases the damage resistance in KTP [17,18].…”

“…The presence of Ti 3 þ in the crystal increases the conductivity and decreases the damage resistance in KTP [17,18]. The growth process and rare earth metal doping were used to modify the physical properties and to reduce the defects in the KTP crystals [19][20][21]. Ionic conductivity and thermal stability are the major concerns in the processing of waveguides and producing stable waveguide device [22][23][24].…”