用于近红外脉冲激光二次谐波产生的非线性晶体KNbO3
KNbO3晶体是具有钙钛矿结构的氧八面体铁电体。由于具有较大的非线性光学系数（d31=15.8pm/V；d32=18.3pm/V）、较宽的透明范围（0.4~5mm）和不受光折变效应的影响，是利用QPM进行非线性频率转换的理想选择。KNbO3晶体的平均折射率为2.2，正入射反射率理论值为14%，理论透过率大于80%。KNbO3具有高的二阶（非线性）系数和良好的相位匹配特性，可用于860nm附近波长范围的低功率激光二极管倍频、850-1000nm范围的Ti:sapphire激光器和1064nm的Nd:YAG激光器。此外，KNbO3还可用于Nd:YAG激光器在基波或二次谐波波长下的光参量振荡，在0.7～3μm的近红外光谱区产生可调谐辐射。
固态蓝绿色激光器具有性能稳定、结构紧凑、可集成等优点，在光存储、光通信、激光医疗仪器等领域具有良好的应用前景，是目前国际上的研究热点。实现这一目标的一个可行途径是利用半导体近红外激光倍频实现蓝绿光输出。目前，能使半导体近红外激光倍频的晶体是铌酸钾（KNbO3）。KNbO3是一种有趣的非线性光学材料。二次谐波产生、和频混频和光参量振荡是将可用激光波长转换成蓝绿色和近红外光谱区域的重要过程。
参数
| 化学式 | KNbO3 |
| 晶体结构 | 斜方，mm2 |
| 晶格参数 | a = 5.6896Å, b = 3.9692Å, c = 5.7256Å |
| 质量密度 | 4.617 g/cm3 |
| 熔点 | 1333 K |
| 居里温度 | 498 K |
| 介电轴和结晶轴的分配 | X, Y, Z ⇒ b, a, c |
| P = 0.101325MPa时的比热cp | cp = 767 J/kgK |
| 导热系数 | κ > 3.5 W/mK |
| 热膨胀 | aa=5.010×10-6/℃; ab=1.410×10-5/℃; ac=5.010×10-7/℃ |
| 属性 | 数值 |
| 透明范围 | 400-5500 nm |
| 红外截止波长 | 5.5 μm |
| 吸收损失 | <=1%/cm 在1064 nm |
| 损坏阈值 | <= 4 J / cm2在527 nm（500ps，单脉冲） |
| <= 6 J / cm2在1054 nm（700ps，单脉冲） |
| 属性 | 数值 |
| 非线性光学系数 | d31=-15.8 pm/V, d32=-18.3 pm/V at 1064 nm |
| 最短SHG波长 | 425 nm（Ⅰ型NCPM，y切或a切） |
| Ⅰ型SHG的接受角为1064 nm | Dq = 0.24 mrad / cm（内部） |
| Ⅰ型SHG的接受温度为1064 nm | DT=0.3 ℃/cm |
| λ [μm] | α [cm−1] | Note |
| 0.423 | 0.13 ± 0.02 | 沿轴，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 | 沿轴，E || b |
| 1.0642 | 0.0018–0.0025 | 沿b轴 |
| 3 | 0.05 | 沿c轴 |
| 0.03 | 沿a轴 | |
| 3.5 | 0.05 | 沿c轴 |
| 0.02 | 沿a轴 | |
| 4 | 0.08 | 沿c轴 |
| 0.08 | 沿a轴 | |
| 4.5 | 0.27 | 沿c轴 |
| 0.45 | 沿a轴 | |
| 5 | 1.21 | 沿c轴 |
| 1.85 | 沿a轴 | |
| 5.5 | 7.6 | 沿c轴 |
| 4.9 | 沿a轴 |
| λ [μm] | τp [ns] | β × 1011 [cm/W] |
| 0.846 | CW | 320 ± 50 |
| λ [μm] | nX | nY | nZ |
| 0.43 | 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 |
| 0.86 | 2.2784 | 2.2372 | 2.1338 |
| 1.064 | 2.2576 | 2.2195 | 2.1194 |
| 1.5 | 2.2341 | 2.1992 | 2.1029 |
| 2 | 2.2159 | 2.1832 | 2.0899 |
| 2.5 | 2.1981 | 2.1674 | 2.0771 |
| 3 | 2.1785 | 2.1498 | 2.063 |
| λ [μm] | γ × 1015 [cm2/W] | Note |
| 0.85 | 1.87 ± 0.35 | 沿Y |
| XY平面 | deeo = d32 sin2 φ + d31 cos2 φ |
| YZ平面 | dooe = d32 sin θ |
| XZ平面，θ<Vz | doeo = deoo = d31 sin θ |
| XZ平面，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 |
| 相互作用波长[μm] | φexp [deg] | θexp [deg] |
| XY平面，θ=90◦ | ||
| SHG, e + e ⇒ o | ||
| 0.946 ⇒ 0.473 | ≈30 | |
| 4.7599 ⇒ 2.37995 | 69.9 | |
| YZ 平面, 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 平面, 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 | |
| 相互作用波长[μm] | T [◦C] |
| 沿X轴 | |
| 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 |
| 沿Y轴 | |
| 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 |
| 相互作用波长[μm] | T [◦C] | θpm [deg] | Δθint [deg] | Δφint [deg] |
| XZ平面，φ=0◦ | ||||
| SHG, o + o ⇒ e | ||||
| 1.0642 ⇒ 0.5321 | 20 | 71 | 0.013–0.014 | |
| 沿Y轴 | ||||
| SHG, type I | ||||
| 0.857 ⇒ 0.4285 | 20 | 90 | 0.659 | 1.117 |
| 相互作用波长[μm] | T [◦C] | θpm [deg] | ΔT [◦C] |
| 沿X轴 | |||
| SHG, type I | |||
| 0.982 ⇒ 0.491 | 18.7 | 90 | 0.95 |
| 1.0642 ⇒ 0.5321 | 181 | 90 | 0.27–0.32 |
| 沿Y轴 | |||
| 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 |
| 相互作用波长[μm] | θexp [deg] | ΔT [◦C] |
| YZ 平面, 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 平面, 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 |
| 沿X轴 | λ1 = 0.97604 + 2.53 × 10−4 T + 1.146 × 10−6 T 2 |
| 沿Y轴 | λ1 = 0.85040 + 2.94 × 10−4 T + 1.234 × 10−6 T 2 |
| 沿X轴(1.0642 μm ⇒ 0.5321 μm) | 1.10 × 10−4 K−1 |
| 沿Y轴(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 | 沿b轴，E || c |
| 12–15 | 沿b轴，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小时 |
| 1.054 | 0.7 | 11 | 沿a轴，E⊥c |
| 18 | 沿b轴，E⊥c | ||
| 37 | 沿b轴，E || c | ||
| 1.0642 | 25 | 0.15–0.18 | |
| 0.1 | >100 |
 |  |
KNbO3-相位匹配角的温度变化 | 室温下KNbO3的折射率分散 |
 |  |
KNbO3-透射光谱 | KNbO3-光学吸收 |
特点
应用
参考文献
新闻
特点
- 非线性光学系数大
- 光照射下的高稳定性
- 非线性光学系数高
- 出色的光折变特性
- 有利的相位匹配特性
应用
- 电光学和非线性光学
- 激光二极管的光折变应用
- 近红外中的动态全息和光学相位共轭
- 光波导
- 光学二次谐波产生（SHG）
- 倍频器
参考文献
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