各向异性透明晶体如方解石、石英等的折射率，是其固有的特性，称为永久双折射。

The polarization dependence with the refractive index might have a range of consequences, several of that happen to be remarkably vital in nonlinear optics and laser technological innovation:

直光纤只有很小的随机双折射，即使这样其中的光传输一段距离后偏振状态也会发生变化。存在保偏光纤，是利用了很强的双折射来抑制这些效应。 

If waves with diverse polarization directions propagate collectively while in the waveguide, their section relation is restored just after integer multiples in the propagation conquer length.

Typically Sure. The refractive index in addition to the index difference between two polarizations is generally wavelength-dependent. That is commonly exploited for birefringent period matching, such as.

类似的，激光光束在存在热效应诱导的双折射效应的激光器晶体中传输时，偏振态也发生变化。这一变化与位置有关，因为双折射轴方向是变化的（例如，通常是轴向变化）。这一变化（与激光器谐振腔中的偏振光元件结合）是去极化损耗的来源。 

Figure seven illustrates a birefringent (anisotropic) crystal positioned in between two polarizers whose vibration Instructions are oriented perpendicular to one another (and lying in Instructions indicated because of the arrows close to the polarizer and analyzer labels).

即使是各向同性介质，也会由于存在不均匀的机械应力而产生双折射。这可以在两个交叉偏振器间放置一块有机玻璃观察：当施加应力到有机玻璃上，可以看到由于应力诱导的与波长相关的双折射效应而产生的彩色图像。

For bulk optical materials, it is also prevalent to take into account the difference of refractive indices for the two polarization Instructions. The bigger that variation, the larger sized the obtained retardance per millimeter of propagation size.

双折射现象的明显例子是方解石。透过方解石的菱面体就可以看到明显重影。

On the other hand, the slowest wavefronts take place when the wave travels along the limited axis of the ellipsoid. This axis is termed the gradual axis. Between these two extremes, wavefronts touring in other Instructions expertise a gradient of refractive index, that's dependent on orientation, and propagate with velocities of intermediate values.

If a linearly polarized laser beam propagates by way of a birefringent medium, you'll find frequently two polarization parts with various wavenumbers. Hence, the optical phases of the two linear polarization parts evolve differently, and For that reason the resulting polarization condition (within the superposition of the two parts) changes for the duration of propagation.

We provide a wide array of polarizers and polarization optics for many alternative employs. Choosing the proper polarization optic on your software is usually a bewildering endeavor, as we offer a wide range for a number of makes use of.

For propagation alongside the optical axis, the electric field can only be perpendicular to that axis, to ensure that a single obtains the everyday index for just about any polarization direction. In that condition, no birefringence is seasoned.

Alternatively, the amazing wave deviates towards the remaining and travels with click here the electric vector perpendicular to that of the standard wave. Due to the fact calcite is really a negatively birefringent crystal, the everyday wave would be the slow wave plus the extraordinary wave could be the rapidly wave.