KTP

Advantages:

·         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

Basic properties:

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

1172° C incongruent

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/

Nonlinear Optical Properties:


Phase matchable SHG range:

497 - 1800nm

Nonlinear optical coefficients:

d31=6.5pm/v, d32=5pm/v, d33=13.7pm/v,d24=7.6pm/v,d15=6.1pm/v
deff(II)» (d24 - d15)sin2f sin2q - (d15sin2q + d24cos2f)sinq

For type II SHG of a Nd:YAG:

laser at 1064nm:

PM angle: q =90° , f =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° )
Optical damage threshold: > 450MW/cm2, (@ 1064nm, 10ns, 10Hz)

Electro-optic coefficients:
r13
r23
r33
r51
r42

Low frequency (pm/V) 
9.5
15.7 
36.3 
7.3
9.3 

High frequency (pm/V)
  8.8
13.8
35.0
6.9
8.8

Dielectric constant:

e eff=13

Optical Properties:


Transmitting range:

350 nm - 4500 nm

Refractive indices:

nx

 ny

 nz

1064nm
532nm

1.7377 
1.7780 

1.7453 
1.7886 

1.8297
1.8887

Sellmeier equations:

( l in m m)

nx2=3.0065+0.03901/(l2-0.04251)-0.01327l2
ny2=3.0333+0.04154/(l2-0.04547)-0.01408l2
nz2=3.3134+0.05694/(l2-0.05556)-0.01682l2

Therm-optic coefficients:

dnx/dT=1.1x10-5/° C, dny/dT=1.3x10-5/° C, dnz/dT=1.6x10-5/° C

Absorption coefficient:

a < 1% cm-1 @1064nm and 532nm

Applications:

·         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 600nm-4500nm tunable output.

·         E-O modulators, optical switches, directional couplers.

·         optical waveguides for integrated NLO and E-O devices

NEWPHOTONS provide KTP with:

  • Standard size of KTP crystal for DPSS application;

  • strict quality control on optical Standard homogeneity, transmission and scattering

  • quick delivery

  • unbeatable price and quantity discount

  • free technical support

  • AR-coating, mounting and re-polishing service

  • mass Production to Support Industrial and Commercial Applications;

Applications for SHG and SFG 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. To date, extra- and intra-cavity frequency doubled Nd:lasers using KTP have become a preferred source of pumping visible dye lasers and tunable Ti:Sapphire lasers as well as their amplifiers. Applied to diode-pumped Nd:laser, KTP has provided the basis for the construction of compact visible solid state laser systems.

Application 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 output from visible (600nm) to mid-IR (4500nm), referring to Fig. 1 and Fig. 2.

KTP's OPO results in stable, continuous outputs of femtosecond pulse of 108 Hz repetition rate and miliwatt average power levels in both signal and idler output. KTP's OPO pumped by a 1064nm Nd:YAG laser has generated above 66% efficiency for degenerately converting to 2120nm.

The recently developed new application is the non-critical phase-matched (NCPM) KTP OPO/OPA pumped by the tunable lasers such as Ti:Sapphire, Alexandrite and Cr:LiSrAlF6 (see right figure). The NCPM KTP OPO keeps the KTP crystal fixed in X-axis and tunes the pumping wavelength. If a tunable Ti:Sapphire laser is used as a pumping source (0.7 mm to 1 mm), the output can cover the wavelength range from 1.04mm to 1.45 mm (signal) and from 2.15 mm to 3.2 mm (idler). Due to the favorable NLO properties of NCPM KTP, as high as 45% conversion efficiency was obtained with narrow output bandwidth and good beam quality.

Application 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


Material

e

n

r
(pm/V)

Phase
k(10-6/° C)

N7r2/e 
(pm/V)2

r
(pm/V)

Amplitude
k(10-6/° C)

n7r2/e
  (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

When these properties are combined with high damage threshold, wide optical bandwidth (>15GHZ), thermal and mechanical stability and low loss, KTP can be expected to replace a considerable volume of LiNbO3 crystals as E-O modulators.

Applications for Optical Waveguides:

Based on the ion-exchange process on KTP substrate, low loss optical waveguides developed for KTP have created novel applications of integrated optics. 

Recently, type II SHG conversion efficiency of 20%/W/cm2 was achieved by balanced phase matching, in which the phase mismatch from one was balanced against a phase mismatch of opposite sign from a second section. Furthermore, segmented KTP waveguides have been applied to type I quasi-phase-matchable SHG of 760-960mm for tunable Ti:Sapphire laser and directly doubled diode laser for 400-430nm output. Conversion efficiency in excess of 100%/W/cm2 have been obtained.

NEWPHOTONS Warranty on KTP Specifications:

• Transmitting 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 code: 10/5 to MIL-O-13830A
• Parallelism: better than 20 arc seconds
• Perpendicularity: 5 arc minutes
• Angle tolerance: D q < ± 0.5° , D f < ± 0.5°
• AR coating: R< 0.2% at 1064nm and R<1.0% at 532 nm.
• Quality Warranty Period: one year under proper use.

Standard Product:

Part No.

Dimension

Application

Coating

Type

KTP0101

2x2x3mm

SHG@1064nm

AR/HR coating

II

KTP0102

2x2x5mm

SHG@1064nm

AR/HR coating

II

KTP0103

3x3x3mm

SHG@1064nm

DBAR-coating

II

KTP0104

3x3x5mm

SHG@1064nm

DBAR-coating

II

KTP0105

3x3x10mm

SHG@1064nm

DBAR-coating

II

KTP0107

7x7x20mm

OPO for 1064à1570nm

AR coating

II

AR Coating: AR@1064nm&532nm; HR Coating: HR@1064nm&HT@532nm