Large nonlinear optical coefficient
Wide angular bandwidth and small walk-off angle
Broad temperature and spectral bandwidth
High electro-optic coefficient and low dielectric constant
Large figure of merit
Nonhydroscopic, chemically and mechanically stable
Chemical and Structural Properties of KTP Crystal
Orthorhombic, Space group Pna21, Point group mm2.
a=6.404 Å, b=10.616 Å, c=12.814 Å
Thermal Expansion Coefficient
αx=11×10-6/K, αy=9×10-6/K, αz=0.6×10-6/K
Optical and Nonlinear Optical Properties of KTP Crystal
350 nm ~ 4500 nm
Thermo-optic Coefficient [K-1](@1064nm)
dnx/dT=6.1×10-6 dny/dT=8.3×10-6 dnz/dT=14.5×10-6
<0.1% cm-1 @1064nm <1% cm-1 @532nm
For Type II SHG of
Temperature Acceptance: 24 °C·cm-1
deff(II)≈(d24-d15)sin2φsin2θ-(d15sin2φ + d24cos2φ)sinθ
Non-vanished NLO Susceptibilities [pm/V]
d31=6.5 d24=7.6 d32=5 pm/V d15=6.1 d33=13.7
Applications for SHG and SFG of Nd: lasers
KTP is the most commonly used material for frequency doubling of Nd:YAG and other Nd-doped lasers, particularly when the power density is at a low or medium level. To date, extra- and intra-cavity frequency doubled Nd:lasers using KTP have become a preferred pumping source for visible dye lasers and tunable Ti:Sapphire lasers as well as their amplifiers. They are also useful green sources for many research and industry applications.
* More than 80% conversion efficiency and 700mJ green laser were obtained with a 900mJ injection-seeded Q-switch Nd:YAG lasers by using extra-cavity KTP.
* 8W green laser was generated from a 15W LD pumped Nd:YVO4 with intra-cavity KTP.
* 200mW green outputs are generated from 1 W LD pumped Nd:YVO4 lasers by using THATSHIGH's 2x2x5mm KTP and 3x3x1mm Nd:YVO4.
* 2-5mw green outputs are generated from 180mw LD pumped Nd:YVO4 and KTP glued crystals. For more details, please refer to Glued Crystals.
KTP is also being used for intracavity mixing of 0.81μm diode and 1.064μm Nd:YAG laser to generate blue light and intracavity SHG of Nd:YAG or Nd:YAP lasers at 1.3μm to produce red light.
Applications for OPG, OPA and OPO
As an efficient OPO crystal pumped by a Nd:laser and its second harmonics, KTP plays an important role for parametric sources for tunable outputs from visible (600nm) to mid-IR (4500nm), as shown in Fig. 3 and Fig. 4.
Generally, KTP's OPOs provide stable and continuous pulse outputs (signal and idler) in fs, with 108 Hz repetition rate and a mW average power level. A KTP’s OPO that are pumped by a 1064nm Nd:YAG laser has generated as high as above 66% efficiency for degenerately converting to 2120nm.
The novel developed application is the non-critical phase-matched(NCPM) KTP OPO/OPA pumped by the X-cut KTP crystal. As shown in Fig.5, for pumping wavelength range from 0.7μm to 1 μm, the output can cover from 1.04μm to 1.45μm(signal) and from 2.15μm to 3.2μm(idler). More than 45% conversion efficiency was obtained with narrow output bandwidth and good beam quality.
THATSHIGH KTP Crystal Coating Service
□ Dual Band AR-coating (DBAR) for SHG of 1064nm with following features:
● Low reflectance (R<0.15% @ 1064nm; R<0.5% @ 532nm)
● High damage threshold (>400MW/cm2 @ 1064nm & 532nm)
● Long durability
□ Broad band coating for OPO applications.
□ High reflectivity coating: HR @ 1064nm (R>99.8%) & HT @ 532nm (T>95%)
□ Other coating types are available upon request.
THATSHIGH Specifications for KTP Crystal
(W±0.1mm) ×(H±0.1mm) ×(L+0.5/-0.1mm) (L≥2.5mm)
Δθ ≤ 0.25° Δφ ≤ 0.25°
90% of central area
> 0.5 for 1064nm, TEM00, 10ns, 10Hz (AR-coated)
< λ/8 @ 633nm
Surface Quality [S/D]
< λ/8 @ 633nm
AR coating available upon request
No visible scattering paths or centers [inspected by 50mW green laser]