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KNbO3 Nonlinear Crystal

17 Jul 2019

Description

Non-linear crystal KNbO3 for second-harmonic generation of near infrared pulsed laser light

KNbO3 crystal is an oxygen octahedra ferroelectric with perovskite structure. Is a good candidate for nonlinear frequency conversion using QPM, due to its large nonlinear optical coefficient (d31=15.8 pm/V;d32=18.3 pm/V), wide transparency range (0.4~5 mm) and freedom from photorefractive effects. KNbO3 crystals have an average refractive index of 2.2.The theoretical value of normal incident reflectivity is 14% and the theoretical transmittance is more than 80%. Because of its high second-order (nonlinear) coefficients and favorable phase-matching properties KNbO3 is the material of choice for doubling low-power laser diodes in the wavelength region near 860 nm, Ti: sapphire lasers in the range 850-1000 nm, and Nd:YAG lasers at 1064 nm. In addition, KNbO3 can be used for optical parametric oscillation when pumped by Nd:YAG lasers at either the fundamental or the second-harmonic wavelength, producing tunable radiation in the near-IR spectral region between 0.7 and 3 μm.

The solid-state blue-green laser has stable performance, compact structure and integrability, which makes it has a good application prospect in optical storage, optical communication and laser medical instrument, etc. It is a research hotspot in the world at present. A feasible way to achieve this goal is to realize blue and green light output by semiconductor near infrared laser frequency doubling. Currently, the crystal that can octave the semiconductor near infrared laser frequency is potassium niobate (KNbO3). KNbO3 is an interesting nonlinear material for optical and electro-optical applications. Second-harmonic generation, sum frequency mixing, and optical parametric oscillation are important processes for converting available laser wavelengths into the blue-green and the near-IR spectral regions.

Parameter

 

Chemical formula KNbO3
Crystal structure Orthorhombic,mm2
Lattice Parameter a = 5.6896Å, b = 3.9692Å, c = 5.7256Å
Mass density 4.617 g/cm3
Melting Point 1333 K
Curie temperature 498 K
Assignment of dielectric and crystallographic axes  X, Y, Z ⇒ b, a, c
Specific heat capacity cp at P = 0.101325MPa cp = 767 J/kgK
Thermal conductivity coefficient κ > 3.5 W/mK
Thermal Expansion aa=5.010×10-6/℃; ab=1.410×10-5/℃; ac=5.010×10-7/℃
Property Value
Transparency Range 400-5500 nm
IR cutoff wavelength  5.5 μm
Absorption loss <=1%/cm at 1064 nm
Damage Threshold <=4 J/cm2 at 527 nm(500ps,single pulse)
<=6 J/cm2 at 1054 nm(700ps,single pulse)
Property Value
Nonlinear Optical Coefficient d31=-15.8 pm/V, d32=-18.3 pm/V at 1064 nm
The shortest SHG wavelength 425 nm(typeⅠ NCPM,y-cut or a-cut)
Acceptance Angle for typeⅠSHG of 1064 nm Dq=0.24 mrad/cm(internal)
Acceptance Temperature for  typeⅠSHG of 1064 nm DT=0.3 ℃/cm
λ [μm] α [cm−1] Note
0.423 0.13 ± 0.02 along a axis, E||c
0.458–0.515 0.04–0.07  
0.8–1.1 0.001–0.003  
0.82 0.015  
0.846 0.000034 ± 0.000022 along a axis, E||b
1.0642 0.0018–0.0025 along b axis
3.0 0.05 along c axis
0.03 along a axis
3.5 0.05 along c axis
0.02 along a axis
4.0 0.08 along c axis
0.08 along a axis
4.5 0.27 along c axis
0.45 along a axis
5.0 1.21 along c axis
1.85 along a axis
5.5 7.6 along c axis
4.9 along a axis
λ [μm] τp [ns] β × 1011 [cm/W]
0.846 CW 320 ± 50
λ [μm] nX nY nZ
0.430 2.4974 2.4145 2.2771
0.488 2.4187 2.3527 2.2274
0.514 2.3951 2.3337 2.2121
0.633 2.3296 2.2801 2.1687
0.860 2.2784 2.2372 2.1338
1.064 2.2576 2.2195 2.1194
1.500 2.2341 2.1992 2.1029
2.000 2.2159 2.1832 2.0899
2.500 2.1981 2.1674 2.0771
3.000 2.1785 2.1498 2.063
λ [μm] γ × 1015 [cm2/W] Note
0.850 1.87 ± 0.35 along Y
XY plane deeo = d32 sin2 φ + d31 cos2 φ
YZ plane dooe = d32 sin θ
XZ plane, θ <Vz doeo = deoo = d31 sin θ
XZ plane, θ > Vz dooe = d31 sin θ
|d32(0.852 μm)| = 11.0 ± 0.6 pm/V
|d33(0.852 μm)| = 22.3 ± 1.1 pm/V
|d24(1.064 μm)| = 12.5 ± 0.6 pm/V
|d32(1.064 μm)| = 10.8 ± 0.6 pm/V
|d33(1.064 μm)| = 19.6 ± 1.0 pm/V
|d32(1.313 μm)| = 9.2 ± 0.5 pm/V
|d33(1.313 μm)| = 16.1 ± 0.8 pm/V
|d15(1.064 μm)| = (41.2 ± 0.8) × d11(SiO2) = 12.4 ± 0.2 pm/V
|d24(1.064 μm)| = (42.8 ± 0.8) × d11(SiO2) = 12.8 ± 0.2 pm/V
|d31(1.064 μm)| = (39.5 ± 0.6) × d11(SiO2) = 11.9 ± 0.2 pm/V
|d32(1.064 μm)| = (45.7 ± 0.6) × d11(SiO2) = 13.7 ± 0.2 pm/V
|d33(1.064 μm)| = (68.5 ± 0.6) × d11(SiO2) = 20.6 ± 0.2 pm/V
Interacting wavelengths [μm] φexp [deg] θexp [deg]
XY plane, θ = 90◦
SHG, e + e ⇒ o
0.946 ⇒ 0.473 ≈30  
4.7599 ⇒ 2.37995 69.9  
YZ plane, φ = 90◦
SHG, o + o ⇒ e
0.86 ⇒ 0.43   83.5
0.89 ⇒ 0.445   70.7
0.92 ⇒ 0.46   64
0.94 ⇒ 0.47   60.5
1.0642 ⇒ 0.5321   46.4
1.3188 ⇒ 0.6594   30.6
1.3382 ⇒ 0.6691   29.7
3.5303 ⇒ 1.76515   37.3
4.7291 ⇒ 2.36455   77.3
SFG, o + o ⇒ e
1.3188 + 0.6594 ⇒ 0.4396   62.3
1.3188 + 1.0642 ⇒ 0.5889   37.7
4.7762 + 3.1841 ⇒ 1.9105   46.6
5.2955 + 3.5303 ⇒ 2.1182   59.5
XZ plane, φ = 0◦, θ > Vz
SHG, o + o ⇒ e
1.0642 ⇒ 0.5321   70.4
1.3188 ⇒ 0.6594   56.8
1.3382 ⇒ 0.6691   56.2
3.5303 ⇒ 1.76515   58.8
SFG, o + o ⇒ e
1.3188 + 1.0642 ⇒ 0.5889   62.6
5.2955 + 3.5303 ⇒ 2.1182   86.1
Interacting wavelengths [μm] T [◦C]
along X axis
SHG, type I
0.972 ⇒ 0.486 −20
0.982 ⇒ 0.491 18.7
0.986 ⇒ 0.493 20
0.988 ⇒ 0.494 20
1.047 ⇒ 0.5235 162
1.0642 ⇒ 0.5321 178
along Y axis
SHG, type I
0.8385 ⇒ 0.41925 −34.2
0.8406 ⇒ 0.4203 −28.3
0.842 ⇒ 0.421 −22.8
0.846 ⇒ 0.423 -11.5
0.856 ⇒ 0.428 15
0.857 ⇒ 0.4285 20
0.8593 ⇒ 0.42965 20
0.86 ⇒ 0.43 22
0.8615 ⇒ 0.43075 30
0.862 ⇒ 0.431 34
0.879 ⇒ 0.4395 70
0.9289 ⇒ 0.46445 158
0.95 ⇒ 0.475 180
SFG, type I
0.6764 + 1.0642 ⇒ 0.41355 -4
0.6943 + 1.0642 ⇒ 0.42017 27.2
Interacting wavelengths [μm] T [◦C] θpm [deg] Δθint [deg] Δφint [deg]
XZ plane, φ = 0◦
SHG, o + o ⇒ e
1.0642 ⇒ 0.5321 20 71 0.013–0.014  
along Y axis
SHG, type I
0.857 ⇒ 0.4285 20 90 0.659 1.117
Interacting wavelengths [μm] T [◦C] θpm [deg] ΔT [◦C]
along X axis
SHG, type I
0.982 ⇒ 0.491 18.7 90 0.95
1.0642 ⇒ 0.5321 181 90 0.27–0.32
along Y axis
SHG, type I
0.8385 ⇒ 0.41925 −34.2 90 0.27
0.842 ⇒ 0.421 −22.8 90 0.3
0.855 ⇒ 0.4275 26.4 90 0.265
0.92 ⇒ 0.46 163.5 90 0.285
SFG, type I
0.6764 + 1.0642 ⇒ 0.41355 -4 90 0.35
Interacting wavelengths [μm] θexp [deg] ΔT [◦C]
YZ plane, φ = 90◦
SHG, o + o ⇒ e
1.0642 ⇒ 0.5321 46.4 0.39
1.3382 ⇒ 0.6691 29.7 0.59
3.5303 ⇒ 1.76515 37.1 2.3
SFG, o + o ⇒ e
5.2955 + 3.5303 ⇒ 2.1182 59.5 2.4
XZ plane, φ = 0◦, θ >Vz
SHG, o + o ⇒ e
1.0642 ⇒ 0.5321 71.4 0.77
1.3382 ⇒ 0.6691 56.2 2.2
3.5303 ⇒ 1.76515 58.1 10.1
along X axis λ1 = 0.97604 + 2.53 × 10−4 T + 1.146 × 10−6 T 2
along Y axis λ1 = 0.85040 + 2.94 × 10−4 T + 1.234 × 10−6 T 2
along X axis (1.0642 μm ⇒ 0.5321 μm) 1.10 × 10−4 K−1
along Y axis (0.92 μm ⇒ 0.46 μm) 1.43 × 10−4 K−1
λ [μm] τp [ns] Ithr [GW/cm2] Note
0.527 0.5 8.8–9.4 along b axis, E||c
  12–15 along b axis, E⊥c
0.5321 25 0.15–0.18  
10 0.055  
0.8 0.0002 >200 1 kHz
1.047 11 >0.03 4 kHz, 2000 hours
1.054 0.7 11 along a axis, E⊥c
  18 along b axis, E⊥c
  37 along b axis, E||c
1.0642 25 0.15–0.18  
  0.1 >100  
KNbO3-Temperature-variation-of-phase-matching-angle KNbO3-Dispersion-of-refractive-index-at-room-temperature
KNbO3-Transmittance Spectrum KNbO3-Optical-Absorbance

 

Feature

  • Large nonlinear optical coefficients
  • High stability under light irradiation
  • High nonlinear optical coefficient
  • Excellent photo-refractive characteristics
  • Favorable phase-matching properties

Application

  • Electro-optics and nonlinear optics
  • Photorefractive applications with laser diodes
  • Dynamic holography and optical phase conjugation in the near infrared
  • Optical wave guides
  • Optical Second Harmonic Generation(SHG)
  • Frequency doubler

CONTACT DETAILS
Nanjing Crylink Photonics Co.,Ltd
No.3, Hengda Road, Economic and Technological Development Zone, Nanjing, China
No.200,Zhaoxian Road,Jiading District,Shanghai City
Nanjing
Jiangsu
210038
China
Tel: (86)025-68790684
Fax: (86)025-68790685
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