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
|
