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KTP Crystals
Description
KTP (KTiOPO4) is a nonlinear optical crystal, which possesses excellent nonlinear and electro-optic properties. It has
large nonlinear optical coefficients and wide angular bandwidth and small walk-off angle, etc. which make it suitable for
various nonlinear frequency conversion and wave guide online_ordering.
 
Advantage:
§ Efficient frequency conversion(1064nm SHG conversion efficiency is about 80%)
§ Large nonlinear optical coefficients(15 times that of KDP)
§ Wide angular bandwidth and small walk-off angle
§ Broad temperature and spectral bandwidth
§ High thermal conductivity (2 times that of BNN crystal )
§ Moisture free
§ Minimum mismatch gradient
§ Super-polished optical surface
§ No decomposition below 900
§ Mechanically stable
§ Low cost compare with BBO and LBO
Disadvantage:
§ Gray-tracking at high power limited its application to moderate power density
Additional applications for KTP include mixed frequency, electro-optical modulation, optical parametric generation and
optical waveguide.
 
Application:
§ Frequency Doubling (SHG) of Nd-doped Lasers for Green/Red Output
§ Frequency Mixing (SFM) of Nd Laser and Diode Laser for Blue Output
§ Parametric Sources (OPG, OPA and OPO) for 0.6mm-4.5mm Tunable Output
§ Electrical Optical(E-O) Modulators, Optical Switches, and Directional Couplers
§ Optical Waveguides for Integrated NLO and E-O Devices
 
 
Crystalstructure Orthorhombic, point group mm 2
Melting point 1172°C incongruent
Cell parameters a=6.404?, b=10.616?, c=12.814?, Z=8
Curie point 936°C
Mohs hardness ~5
Density 3.01 g/cm3
Color colorless
Hygroscopic susceptibility no
Specific heat 0.1643 cal/g.°C
Thermal conductivity 0.13 W/cm/°K
Electrical conductivity 3.5x10 -8 s/cm (c-axis, 22°C, 1KHz)
 
Transmitting Range 350nm~4500nm
    nx ny nz
Refractive Indices 1064nm 1.7377 1.7453 1.8297
  532nm 1.7780 1.7886 1.8887
Absorption Coefficients α < 1% / cm @ 1.064 μm    
Phase Matchable Range 0.984-3.4μm      
Therm-Optic dnx / dT= 1.1x10  /°C,dny / dT= 1.3x10  /°C,dnz / dT=1.6x10  /°C
Coefficients        
Nonlinear d31=2.54pm/V,  d32=1.35pm/V,  d33=16.9pm/V
Optical Coefficients d24=3.64pm/V,  d15=1.91pm/V,  at 1.064μm
  deff(II)  (d24-d15)sin2Φsin2θ-(d10sin  Φ+d24cos  Φ)sinθ
    Low frequency High frequency
  <, /SPAN> (pm/V)   (pm/V)
Electro-Optic r13 9.5   8.8
Coefficients r23 15.7   13.8
  r33 36.3   35.0
  r51 7.3   6.9
  r42 9.3   8.8
Dielectric Constant εeff=13      
  nx = 3.0065 + 0.03901/(λ - 0.04251) - 0.01327λ
Sellmeier Equations ny = 3.0333 + 0.04154/(λ - 0.04547) - 0.01408λ
  nz = 3.3134 + 0.05694/(λ - 0.05658) - 0.01682λ
 

 

Fig. 1 represents Type 2 SHG tuning curve of KTP in x-y plane.
In x-y plane the slope d(Dk)/dq is small. This corresponds to
quasi-angular noncritical phase matching, which ensures the
double advantage of a large acceptance angle and a small walk off.
 
 
Fig. 2 represents Type 2 SHG tuning curve of KTP in x-z plane.
in x-z plane the slope d(Dk)/dq is almost zero for wavelengths in
the range 1.5-2.5 m m and this corresponds to quasi-wavelength
noncritical phase matching, which ensures a large spectral acceptance. 
Wavelength noncritical phase matching is highly desirable for frequency
conversion of short pulses.

 
 
Figures 3 and 4 show the phase matching angles for OPO/OPA
pumped at 532 nm in x-y and x-z plane respectively. As a lasing
material for OPG, OPA or OPO, KTP can most usefully be pumped
by Nd lasers and their second harmonic or any other source with
intermediate wavelength, such as a dye laser (near 600 nm). 


 
 
 
 
 
 
 
 
Standard KTP for SHG of 1064nm
 
Part No. Size (mm) q f Coating
S1 S2
KTP001 3x3x5 90° 23.5° AR@1064nm R<0.2%
AR@532nm R<0.5%
AR@1064nm R<0.2%
AR@532nm R<0.5%
KTP002 3x3x5 90° 23.5° HR@1064nm R>99.8%
AR@ 532nm R<0.5%
AR@1064nm R<0.2%
AR@532nm R<0.5%
KTP003 3x3x10 90° 23.5° HR@1064nm R>99.8%
AR@ 532nm R<0.5%
AR@1064nm R<0.2%
AR@532nm R<0.5%

Ms. Lin

Mr. Wen

Ms.Chen