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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.

LaserMas KTP is featured by 

             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


LaserMa offers


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

Table 1. Chemical and Structural properties

Crystal Structure

Orthorhombic, space group Pna21,point group mm2

Lattice Parameter

a=6.404?, b=10.616?, c=12.814?, Z=8

Melting Point   

About 1172C

Mohs Hardness   

5

Density         

3.01 g/cm3

Thermal Conductivity  

13W/m/K

Thermal Expansion Coefficient

x=11x10-6/C, y=9x10-6/C, z=0.6x10-6/C

Table 2. Optical and Nonlinear Optical Properties

Transparency Range

3504500nm

SHG Phase Matchable Range

4971800nm  (Type II)

Therm-optic Coefficients(/C)

dnx/dT=1.1X10-5
dny/dT=1.3X10-5
dnz/dT=1.6X10-5

Absorption  Coefficients

<0.1%/cm at 1064nm,  <1%/cm at 532nm

For Type II SHG of a Nd:YAG laser at 1064nm

 

 

Temperature Acceptance: 24C-cm
Spectral Acceptance: 0.56nm-cm
Angular Acceptance: 14.2mrad-cm ();55.3mrad-cm ()
Walk-off Angle: 0.55

NLO Coefficients

deff(II)(d24-d15)sin2sin2-(d15sin2 + d24cos2)sin

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
( in m)     

nx2=3.0065+0.03901/(2-0.04251)-0.01327 2
ny2=3.0333+0.04154/( 2-0.04547)-0.014082
nz2=3.0065+0.05694/( 2-0.05658)-0.016822

 

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 LASERMA 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 0.81m diode and 1.064m Nd:YAG laser to generate blue light and intracavity SHG of Nd:YAG or Nd:YAP lasers at 1.3m 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, KTPs OPOs provide stable and continuous pulse outputs (signal and idler) in fs, with 108 Hz repetition rate and a mW average power level. A KTPs 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 0.7m to 1 m, the output can cover from 1.04m to 1.45m(signal) and from 2.15m to 3.2m(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

N

R(pm/V)

k(10-6/C)

N7r2/(pm/V)2

r(pm/V)

k(10-6/C)

n7r2/(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 the range of 760-960mm, and directly doubled diode lasers for the 400-430nm outputs.

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-coatings
LASERMA 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.

LaserMa Warranty on KTP Specifications:
Dimension tolerance: (W0.1mm)x(H0.1mm)x(L+0.5/-0.1mm) (L2.5mm)
 (W0.1mm)x(H0.1mm)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 /8 @ 633nm
Transmitting wavefront distortion: less than /8 @ 633nm
Chamfer: 0.2mm@45
Chip: 0.1mm
Scratch/Dig code: better than 10/ 5 to
MIL-PRF-13830B
Parallelism: better than 20 arc seconds
Perpendicularity: 5 arc minutes
Angle tolerance: ȡ0.25, ա0.25
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.

 

 
 
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