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KTA (Potassium Titanyl Arsenate, KTiOAsO4 )
KTA crystal features large non-linear optical and electro-optical coefficients in comparison to KTP and has the added benefit of significantly reduced absorption in the 2 to 5 µm region. It has found more and more applications in second harmonic generation (SHG), sum and difference frequency generation (SFG)/(DFG), optical parametric oscillation/ amplification (OPO/OPA), and electro-optical Q-switching. |
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KTA features
Large nonlinear optical coefficients |
Wide angular bandwidth and small walk-off angle |
Broad temperature and spectral bandwidth |
Large electro-optic coefficients |
Lower absorption in the 3-4 μm range than KTP. |
Nonhydroscopic, chemically and mechanically stable |
High thermal conductivity |
High damage threshold |
KTA is a positive biaxial crystal, with the principal axes X, Y, and Z ( nz>ny>nx ) parallel to the crystallographic axes a, b, and c, respectively.
Structural and Physical Properties
Crystal Structure |
Orthorhombic, space group Pna21, point group mm2 |
Cell Parameters |
a=13.125Å, b=6.5716Å, c=10.786 Å, Z=8 |
Melting Point |
1130oC |
Curie Point |
880oC |
Mohs Hardness |
~ 5 |
Density |
3.45 g/cm3 |
Color |
colorless |
Hygroscopic Susceptibility |
No |
Specific Heat |
0.687 J/g/K |
Thermal Conductivity |
1.8 W/m/K |
Electrical Conductivity |
0.7-3.4 x10-6 s/cm (c-axis, @22 oC, 1KHz) |
Linear Optical Properties:
Transmitting Range |
350 nm - 5500 nm |
Refractive Indices:
1064nm
532nm |
nx ny nz
1.7818 1.7866 1.8680
1.8264 1.8331 1.9310 |
Sellmeier Equations
(l in μm) |
nx2=1.90713+1.23522l2 /(l2-0.19692)-0.01025l2
ny2=2.15912+1.00099l2 /(l2-0.21844)-0.01096l2
nz2=2.14768+1.29559l2/(l2-0.22719)-0.01436l2 |
Thermo-optic Coefficients |
dnx/dT=1.1x10-5/oC, dny/dT=1.3x10-5/oC
dnz/dT=1.6x10-5/oC |
Absorption Coefficient |
a < 1% cm-1 @1064nm and 532nm |
Nonlinear Optical Properties:
Phasematchable SHG Range |
542 - 1800nm |
Nonlinear Optical Coefficients |
d31=2.8pm/v, d32=4.2pm/v,
d33=16.2pm/v,d24=3.2pm/v,
d15=2.3pm/v |
Effective Nonlinearity Expressions |
deff(II)= (d24-d15)sin2fsin2q-(d15sin2f+d24cos2f)sinq |
Electro-optic Coefficients
( Low frequency ) |
r13= 11.5pm/V, r23=15.4pm/V, r33=37.5pm/V |
Dielectric Constant |
eeff=42 |
Standard Products
Part No. |
Dimension |
Application |
Coating |
Type |
KTA0510 |
5x5x10mm |
SHG for 1320nm |
AR@1320 & 660nm |
II |
KTA0720 |
7x7x20mm |
OPO/A for 1530nm |
AR@1064 &1530nm |
II |
| KTA0721 |
7x7x20mm |
OPO/A for 3-4mm |
AR@1064 &1570&3200nm |
II |
Specifications for finished KTA
| Wavefront distortion: less than l/4 @ 633 nm |
| Dimension tolerance: (W +/- 0.1 mm) x (H +/- 0.1 mm) x (L + 0.2 mm/-0.1mm) |
| Clear aperture: > 90% central area |
| Flatness: l/8 @ 633 nm |
| Scratch/dig: 10/5 to MIL-O-13830A |
| Parallelism: better than 20 arc seconds |
| Perpendicularity: 5 arc minutes |
| Angle tolerance: Dq< +/-0.25, Df< +/-0.25 |
Coating and Mount
Standard dual band anti-reflection (DBAR) coatings at 1064nm/1530 nm, 1064/3200nm, or 1320nm/660nm are available. Other coatings are also available upon request. Mounts may be provided free of charge.
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High average power ns OPO @ 1530nm with NCPM KTA
Noncolinear OPCPA in KTA produces intense 160fs pulses @ 1550nm
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