| Potassium Titanyl
Phosphate (KTiOPO4,KTP) |
 |
Potassium Titanyl Phosphate (KTiOPO3 or KTP) is widely used in both commercial and military
lasers including laboratory and medical systems, range-finders,
lidar, optical communication and industrial systems. |
CASTECH offers for its KTP with:
· Strict quality control
· large crystal size up to 20x20x40mm3 and maximum length of 60mm;
· Quick delivery(2 weeks for polished only, 3 weeks for
coated)
· Unbeatable price and quantity discount
· Technical support
· AR-coating, mounting and re-polishing service
Basic Properties
Table 1. Chemical and
Structural properties
| Crystal Structure |
Orthorhombic, space group Pna21,point
group mm2 |
| Lattice
Parameter |
a=6.404Å,
b=10.616Å, c=12.814Å, Z=8 |
| Melting
Point |
About
1172°C |
| Mohs
Hardness |
5 |
| Density
|
3.01
g/cm3 |
| Thermal
Conductivity |
13W/m/K |
| Thermal
Expansion Coefficient |
αx=11x10-6/°C, αy=9x10-6/°C, αz=0.6x10-6/°C |
Table 2. Optical and
Nonlinear Optical Properties
| Transparency Range |
350~4500nm |
| SHG
Phase Matchable Range |
497
~ 1800nm (Type II) |
| Therm-optic
Coefficient
(/°C, λ
in μm) |
dnx/dT=1.1X10-5
dny/dT=1.3X10-5
dnz/dT=1.6X10-5 |
| Absorption
Coefficient |
<0.1%/cm
at 1064nm <1%/cm at 532nm |
| For Type II SHG of a Nd:YAG
laser at 1064nm
|
Temperature Acceptance: 24°C-cm
Spectral Acceptance: 0.56nm-cm
Angular Acceptance:
14.2mrad-cm (φ);55.3mrad-cm (θ)
Walk-off Angle:
0.55° |
| NLO
Coefficient |
deff(II)≈(d24-d15)sin2φsin2θ-(d15sin2φ + d24cos2φ)sinθ |
| Non-vanished NLO susceptibilities |
d31=6.5 pm/V
d24=7.6 pm/V
d32=5 pm/V
d15=6.1 pm/V
d33=13.7 pm/V |
| Sellmeier
Equations
(λ in μm) |
nx2=3.0065+0.03901/(λ2-0.04251)-0.01327λ 2
ny2=3.0333+0.04154/(λ 2-0.04547)-0.01408λ2
nz2=3.0065+0.05694/(λ 2-0.05658)-0.01682λ2
|
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 CASTECH
's 2x2x5mm KTP and 3x3x1mm Nd:YVO4.
* 2-5mw green outputs are generated from 180mw LD pumped
Nd:YVO4
and KTP 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. |
 |
 |
| Fig.1 Type II KTP SHG in XY
Plane |
Fig 2 Type II KTP SHG in XZ
Plane |
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. |
 |
 |
| Fig.3 OPO pumped
at 532 in X-Z plane |
Fig.4
OPO pumped at 532 in X-Y plane |
| 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. |
 |
| Fig.5 Type II
NCPM OPO |
Applications
for E-O Devices
| In addition to unique NLO
features, KTP also has promising E-O and dielectric properties
that are comparable to LiNbO3These
advantaged properties make KTP extremely useful to various
E-O devices. Table 1 is a comparison of KTP with other E-O
modulator materials commonly used: |
Table 1. Electro-Optic Modulator Materials
| |
|
|
|
Phase |
|
|
Amplitude |
|
| Material |
ε |
N |
R(pm/V) |
k(10-6/°C) |
N7r2/ε(pm/V)2 |
r(pm/V) |
k(10-6/°C) |
n7r2/ε(pm/V)2 |
| KTP
LiNbO3
KD*P
LiIO3 |
15.42
27.9
48.0
5.9 |
1.80
2.20
1.47
1.74 |
35.0
8.8
24.0
6.4 |
31
82
9
24 |
6130
7410
178
335 |
27.0
20.1
24.0
1.2 |
11.7
42
8
15 |
3650
3500
178
124 |
| From Table 1, clearly, KTP
is expected to replace LiNbO3
crystal in the considerable volume application of E-O modulators,
when other merits of KTP are combined into account, such as
high damage threshold, wide optical bandwidth (>15GHZ),
thermal and mechanical stability, and low loss, etc. |
Applications
for Optical Waveguides
| Based on the ion-exchange process
on KTP substrate, low loss optical waveguides developed for
KTP have created novel applications in integrated optics.
Table 2 gives a comparison of KTP with other optical waveguide
materials.
Recently, a type II SHG conversion
efficiency of 20%/W/cm2 was achieved by the balanced
phase matching, in which the phase mismatch from one section
was balanced against a phase mismatch in the opposite sign
from the second . Furthermore, segmented KTP waveguides have
been applied to the type I quasi-phase-matchable SHG of a
tunable Ti:Sapphire laser in range 760-960mm, and directly
doubled diode lasers for the 400-430nm outputs. A conversion
efficiency in excess of 100%/W/cm2 has been obtained. |
Table 2. Electro-Optic Waveguide Materials
| Materials |
r (pm/V) |
n |
eeff (e11e33)1/2 |
n3r/eeff
(pm/V) |
| KTP
LiNbO3
KNbO3
BNN
BN
GaAs
BaTiO3 |
35
29
25
56
56-1340
1.2
28 |
1.86
2.20
2.17
2.22
2.22
3.6
2.36 |
13
37
30
86
119-3400
14
373 |
17.3
8.3
9.2
7.1
5.1-0.14
4.0
1.0 |
AR-coating
CASTECH provides the following AR-coatings:
· Dual Band AR-coating (DBAR) of
KTP for SHG of 1064nm.
low
reflectance (R<0.2% at 1064nm and R<0.5% at 532nm );
high damage threshold (>300MW/cm2 at both wavelengths);
long
durability.
· Broad Band AR-coating (BBAR) of
KTP for OPO applications.
· High reflectivity
coating: HR1064nm&HT532nm, R>99.8%@1064nm, T>90%@532nm.
· Other coatings are available upon
request.
CASTECH Warranty
on KTP Specifications:
· Dimension tolerance: (W±0.1mm)x(H±0.1mm)x(L+0.5/-0.1mm)
(L≥2.5mm)
(W±0.1mm)x(H±0.1mm)x(L+0.1/-0.1mm) (L<2.5mm)
· Clear aperture: central 90% of
the diameter
· No visible scattering paths or
centers when inspected by a 50mW green laser
· Flatness: less than λ/8 @ 633nm
· Transmitting wavefront distortion:
less than λ/8 @ 633nm
· Chamfer: ≤0.2mm@45°
· Chip: ≤0.1mm
· Scratch/Dig code: better than 10/
5 to MIL-O-13830A
· Parallelism: better than 20 arc
seconds
· Perpendicularity: ≤5 arc minutes
· Angle tolerance: Δθ≤0.25°, Δφ≤0.25°
· Damage threshold[GW/cm ]: >0.5
for 1064nm, TEM00, 10ns, 10HZ (AR-coated)
>0.3
for 532nm, TEM00, 10ns, 10HZ (AR-coated)
· Quality Warranty Period: one half
year under proper use.
|
