GTR-KTP crystals
Potassium Titanyl Phosphate (KTiOPO₄), KTP is a nonlinear optical material widely used for frequency doubling solid-state lasers, such neodymium-doped lasers. Conventional KTP is prone to photochromic damage (so called ‘grey tracking’) during high-power 1064 nm second-harmonic generation which tends to limit its use to low and mid-power systems. Grey-track Resistant Potassium Titanyl Phosphate (GTR-KTP) is the latest generation of KTP.

GTR-KTP crystal strengths include:
  • High optical damage threshold > GW/cm2 @ 1064nm, 10ns, 10Hz
  • Low absorption at 1064 and 532nm
  • High optical conversion

GTR-KTP applications include:
  • SHG of Nd-doped laser
  • Frequency mixing (SFM) of Nd and diode lasers to produce blue outputs
  • Parametric sources (OPG, OPA and OPO) for 600 - 4500nm tuneable outputs
  • EO modulators, optical switches and directional couplers
  • Optical waveguides for integrated NLO and EO devices
  • SHG and THG using high power Nd:YAG (1342 and 1319nm)
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GTR-KTP Crystal - Availability
  • Format:
Rods, Discs and Slabs
  • Sizes:
Diameter: 10mm max and Length: 20mm max
GTR-KTP Crystal Properties
Optical Properties Units Value
Transmission/
Transparency Range		 µm 350 - 4500
Refractive Index (n) @1064nm nx = 1.7377

ny = 1.7453

nz = 1.8297
Non-linear Coefficients pm/V d31 = 6.5, d32 = 5.0

d33 = 13.7, d24 = 7.6

d15 = 6.1
Effective Nonlinear Expressions: deff (II) ~ (d24 - d15) x sin2φ.sin2θ - (d15.sin²φ + d24cos²φ).sinθ
Electro-optic Coefficients: pm/V
Absorption Coefficient @1064nm cm‾¹ 0.005
Physical / Thermal Properties Units Value
Chemical Formula KTiOPO₄
Crystal Symmetry/
Structure		 Orthorhombic
Point Group mm2
Melting Point ºC 1172
Thermal Expansion Coeff. @20ºC 10‾⁶/ºC ┴19.0

║ 44
Thermal Conductivity Coeff. @20ºC W/m/ºK 13
Specific Heat Capacity J/g K TBA
Density g/cm³ 3.01
Mohs Hardness 5
Optical Damage Threshold @1.06/ºC,10ns GW/cm² 2
GTR-KTP Crystal - Sellmeier Equations
nx² = 3.0065 + 0.03901/(λ² - 0.04251) - 0.01327λ²

ny² = 3.0333 + 0.04154/(λ² - 0.04547) - 0.01408λ²

nz² = 3.0065 + 0.05694/(λ² - 0.05658) - 0.01682λ²