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YCOB Crystal

Chemical formula:YCa4O(BO3)3 (YCOB)

Introduction:YCOB crystal was first found in 1990s. Because it has good nonlinear optical properties and high temperature piezoelectric properties and it is easy to grow large size crystal with high quality, it attracts attention new in recent years. Compared with LBO crystal which is common used in high power laser system, it has following advantages: no deliquescence, larger effective NLO susceptibilities, larger Temperature Acceptance, similar laser induce damage threshold, less parametric luminescence (three orders less), smaller thermal expansion coefficient and less anisotropy, better processability, shorter growth period by Cz method and cheaper to make larger aperture element. YCOB crystal is suitable for applications in high energy and high power laser fields,including second-harmonic generation (SHG), third-harmonic generation (THG), optical parametric oscillator (OPO), optical parametric amplification(OPA),optical parametric chirped-pulse amplification (OPCPA). Another application is in the field of piezoelectric devices at high temperature. YCOB crystal has very high electric resistivity that can be fabricated as piezoelectric sensors working at the temperature as high as 1000ºC in engines.

Application fields: Laser wavelength conversion: second-harmonic generation (SHG), third-harmonic generation (THG), optical parametric oscillator (OPO), optical parametric amplification(OPA),optical parametric chirped-pulse amplification (OPCPA).

Table 1. General Specifications of YCOB NLO elements

Case

dimension mm

θ

Ф

deff pm/V

SHG@1064nm

30 x 30 x 15

30.8º

180º

1.41

OPA

15 x 15 x 20

28º

180 º

1.32

THG@1064nm

4 x 4 x 7

106 º

77.2 º

NA

    Note: other specs can be fabricated due to customers requirements

Ø Piezoelectric sensors at high temperature: piezoelectric acceleration sensors, pressure sensors, gas sensors, etc.

Table 2. Chemical and Structural Properties of YCOB Crystal

Crystal Structure

Monoclinic, Point group m

Lattice Parameter

a=8.0770 Å, b=16.0194 Å , c=3.5308 Å , 

β=101.167º, Z=2

Melting Point    

About 1510

Mohs Hardness    

6~6.5

Density          

3.31 g/cm3

Thermal Conductivity   

2.6 W/m/K (║X), 2.33 W/m/K (║Y), 3.1 W/m/K (║Z)

Thermal Expansion Coefficient

ax=10.8x10-5/K, ay= -8.8x10-5/K, az=3.4x10-5/K

Table 3. Optical and Nonlinear Optical Properties of YCOB compared with LBO

Properites

YCOB

LBO

Transparency Range

210~2600 nm

160-2600 nm

SHG Phase Matchable Range

724 ~ 2600nm  (Type I)      

1030-2150nm (Type II)

551 ~ 2600nm  (Type I)      

790-2150nm (Type II)

Therm-optic Coefficient

(°C, λ in μm)

dnx/dT=-9.3X10-6
dny/dT=-13.6X10-6
dnz/dT=(-6.3-2.1λ)X10-6

Absorption  Coefficient

<0.1%/cm at 1064nm 

<0.1%/cm at 1064nm    <0.3%/cm at 532nm

Angle Acceptance

0.062 º-cm    (θ, Type I,1064 SHG)

0.19 º-cm    (φ, Type I,1064 SHG)

Temperature Acceptance

112°C-cm   (Type I, 1064 SHG)

4.7 °C-cm   (Type I, 1064 SHG)

Spectral Acceptance

1.19 nm-cm (Type I, 1064 SHG)

1.0 nm-cm (Type I, 1064 SHG)

Walk-off Angle 

1.26° (Type I  1064 SHG)

0.60° (Type I  1064 SHG)

NLO Coefficients

deff(I)=d13sinΦ     (Type I  in XY plane)
deff(I)=d13 sin2θ d12cos2θ   (Type I  in YZ plane)
deff(I)=d12cosθ- d32sinθ  (Type I in XZ plane, VZ>θ>0, Ф=0º)
deff(I)=d12cosθ d32sinθ   (Type I in XZ plane, VZ>θ>0, Ф=180º)

deff(I)=d32cosΦ     (Type I  in XY plane)
deff(I)=d31cos2θ d32sin2θ   (Type I  in XZ plane)
deff(II)=d31cosθ  (Type II in YZ plane)
deff(II)=d31cos2θ d32sin2θ   (Type II in XZ plane) 

Non-vanished NLO susceptibilities

d12 0.24 pm/V; d13 = -0.73 pm/V

d31 = 0.41 pm/Vd32 = 2.35 pm/V

d33 = -1.60 pm/V

d31=1.05 ± 0.09 pm/V
d32= -0.98 ± 0.09 pm/V
d33=0.05 ± 0.006 pm/V

Sellmeier  Equations(λ in μm)      

nx2 = 2.7697 0.02034/(λ2-0.01779)-0.00643λ2

ny2 = 2.8741 0.02213/(λ2-0.01871)-0.01078λ2

nz2 = 2.9107 0.02232/(λ2-0.01887)-0.01256λ2

nx2=2.454140 0.011249/(λ2-0.011350)-0.014591λ2-6.60x10-5λ4
ny2=2.539070 0.012711/(λ2-0.012523)-0.018540λ2 2.0x10-4λ4
nz2=2.586179 0.013099/(λ2-0.011893)-0.017968λ2-2.26x10-4λ4

SICCAS Warranty on YCOB 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/4 @ 633nm
* Transmitting wavefront distortion: less than λ/4 @ 633nm
* Chamfer: ≤0.2mmx45°
* Chip: ≤0.1mm
* Scratch/Dig code: better than 20/10 
* Parallelism: better than 30 arc seconds
* Perpendicularity: ≤5 arc minutes
* Angle tolerance: Δθ≤0.25°, ΔΦ≤0.25° for phasematching cut in main plane
* Damage threshold[GW/cm2 ]: >for 1064nm, TEM00, 10ns, 10HZ (polished only)
                                                  >1 for 1064nm, TEM00, 10ns, 10HZ (AR-coated)
                                                   >0.5 for 532nm, TEM00, 10ns, 10HZ (AR-coated)
* Quality Warranty Period: one year under proper use.

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