Newlight KTP features,
Large nonlinear optical coefficients
Wide angular bandwidth and small walk-off angle
Broad temperature and spectral bandwidth
Nonhydroscopic, chemically and mechanically stable
High thermal conductivity
Flux grown, extremely low cost compared to KTA, BBO and LBO
These favorable features enables KTP to be widely used for frequency doubling (SHG) or sum frequency mixing (SFG) to generate Red/Green/Blue (RGB) outputs, and for optical parameteric oscillator (OPO) or optical parametric amplifier (OPA) to generate visible to mid-infrared tunable wavelengths. KTP is also used in many electro-optic (E-O) devices such as Q-switches and E-O modulators.
Hydrothermally grown gray tracking resistant KTP crystals are available upon request.
Part No. | Description | Application | Thickness | Price | Availability | Add to Cart |
KTP 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=6.404Å, b=10.616Å, c=12.814Å, Z=8 |
Melting Point | 1172oC in congruent |
Curie Point | 936oC |
Mohs Hardness | ~ 5 |
Density | 3.01 g/cm3 |
Color | Colorless |
Hygroscopic Susceptibility | No |
Specific Heat | 0.687 J/g/K |
Thermal Conductivity | 2 W/m/K |
Electrical Conductivity | 3.5x10-8 s/cm (c-axis, @ 22oC, 1 KHz) |
Linear Optical Properties:
Transmitting Range | 350 - 3500 nm |
Refractive Indices 1064 nm 532 nm |
nx ny nz 1.7377 1.7453 1.8297 1.7780 1.7886 1.8887 |
Sellmeier Equations (λ in µm) |
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 |
Thermo-optic Coefficients | dnx/dT=1.1x10-5 /oC, dny/dT=1.3x10-5 /oC dnz/dT=1.6x10-5 /oC |
Absorption Coefficient | α < 1% cm-1 @1064 nm and 532 nm |
Nonlinear Optical Properties:
Phase-matchable SHG Range | 994 - 3600 nm | |
Nonlinear Optical Coefficients | d31=1.95 pm/v, d32=3.9 pm/v, d33=15.3 pm/v,d24=3.9 pm/v, d15=1.95 pm/v |
|
Effective Nonlinearity Expressions | deff(II)= (d24-d15)sin2φsin2θ-(d15sin2φ+ d24cos2φ)sinθ | |
For type II SHG of a Nd:YAG Laser at 1064 nm | PM angle: θ=90°, φ=23.5° Effective SHG coefficient: deff=8.3xd36(KDP) Angular acceptance: 20 mrad-cm Temperature acceptance: 25°C-cm Spectral acceptance: 5.6 Å -cm Walk-off angle: 4.5 mrad (0.26°) |
Application examples:
SHG of Nd:lasers
KTP is the most commonly used material for frequency doubling of Nd:YAG lasers and other Nd-doped lasers, particularly at the low or medium power density. The following table lists the major NLO properties of KTP for frequency-doubling of a Nd:YAG laser.
PM Angle | θ=90o, φ=23.5o |
Effective SHG Coefficient | deff = 8.3xd36(KDP) |
Angular Acceptance | 20 mrad-cm |
Temperature Acceptance | 25 oC-cm |
Spectral Acceptance | 5.6 Å-cm. |
Walk-off angle | 4.5 mrad (0.26o) |
Extra- and intra-cavity frequency doubled Nd:lasers using KTP have become a preferred green laser sources for many R&D, medical, industrial, and commercial applications. By using extra-cavity KTP SHG, a conversion efficiency of over 80% and 700 mJ green power were obtained with a 900 mJ injection-seeded Q-switched Nd:YAG laser.
OPG, OPA and OPO
As an efficient OPO crystal pumped by the fundamental and second harmonics of a Nd:YAG or Nd:YLF laser, KTP plays an important role in parametric sources for tunable output from visible (0.6 um) to mid-IR (4.5 um). The non-critical phase-matched (NCPM) OPO/OPA with a X-cut KTP pumped by 1064nm is particularly useful as the signal output @1.57 um is eye safe. NCPM KTP OPO/OPA pumped by the tunable lasers such as Ti:Sapphire, Alexandrite and Cr:LiSrAlF6 have also been reported with a high efficiency of 45%.
Specifications of KTP components:
Wavefront distortion: | < λ/8 @ 633 nm for Aperture =< 5mm, L =< 5mm |
Dimension tolerance: | (W +/-0.1 mm) x (H +/-0.1 mm) x (L + 0.2/-0.1 mm) (L+0.5/-0.1 mm) for large crystals. |
Clear aperture: | > 90% central area |
Flatness: | λ/8 @ 633 nm |
Scratch/Dig: | 10/5 to MIL-O-13830A |
Parallelism: | better than 20 arc seconds |
Perpendicularity: | 5 arc minutes |
Angle tolerance: | Δθ < +/-0.25o, Δφ < +/-0.25o |
Coatings:
For SHG of 1064 nm, the standard coating is dual band AR (DBAR) at 1064/532 nm with residual reflectivity < 0.2% @ 1064 nm and < 1.0% @ 532 nm per face. HR @ 1064 nm and HT @ 532 nm is available for compact laser-SHG devices.
Temperature-controlled oven:
KTP may suffer from optical damage known as "gray tracking". Maintaining KTP crystal at an elevated temperature ( e.g., 80oC) can help to reduce the formation of gray tracking. Please refer here for more information on the oven for crystal heating.
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