定义：一种光纤，其中光传播是基于光子带隙效应。

光子带隙光纤是利用光子带隙效应而不是利用具有较大折射率的纤芯区域导光。通常情况下，需要采用一个两维的布拉格反射镜。这种导波机制只能工作在有限的波长区域。 

最早的这种光纤也称为布拉格光纤，是采用具有不同折射率的同心圆环做成的。后来，发展了另一种特殊类型的光子晶体光纤，也是利用光子带隙实现导波，但是采用小的空气孔。 

纤芯本身的折射率可能比包层结构中的要低。纤芯也可以是空心的（参阅空芯光纤），因此其折射率就是空气折射率。由于大部分的光在空气中而不是在玻璃中传播（空气导引光纤），这种空芯光子带隙光纤可以用来传导玻璃中吸收较高的光谱区域的光。例如，[[CO2激光器]]中出射的光可以在其中传播。并且，空芯光纤具有较弱的非线性，因此可以用于很高峰值功率的超短脉冲的色散压缩，或传输高功率激光光束。但是由于其对允差的要求很严格，光子带隙光纤制备比较困难，并且只有在有限带宽时可以低损耗透射，具有相对较高的传播损耗。并且与折射率导引光纤相比，很难建立其传播模型。

Definition: optical fibers where light is guided based on a photonic bandgap effect

More general terms: photonic crystal fibers, hollow-core fibers

Photonic bandgap fibers are optical fibers where a photonic bandgap effect rather than a fiber core region with increased refractive index is utilized for guiding light. Such a guiding mechanism normally works only in a limited wavelength region. The conceptually simplest kind of realization is a kind of two-dimensional Bragg mirror.

The earliest realization of photonic bandgap fibers, called Bragg fibers, was based on concentric rings with different refractive index [1]. Later, a special type of photonic crystal fiber has been developed, which also implements guidance with a photonic bandgap [3, 6], but in this case based on tiny air holes.

The refractive index of the core itself can be lower than that of the cladding structure. The core can even be hollow (→ hollow-core fibers), so that its refractive index is that of air (close to 1). As most of the light is then propagating in air rather than in glass (air-guiding fibers), such kinds of hollow-core photonic bandgap fibers may be used for guiding light in spectral regions where the absorption in the glass is relatively high. For example, light from a CO₂ laser may be guided. Also, hollow-core fibers have a very weak nonlinearity, which makes them promising e.g. for the dispersive compression of ultrashort pulses with high peak power, or for the delivery of high-power laser beams.

However, photonic bandgap fibers are generally more difficult to produce due to their tight fabrication tolerances, have a limited bandwidth for low-loss transmission, and often exhibit relatively high propagation losses. It is also substantially more difficult to understand and model their propagation characteristics, compared to index-guiding fibers.

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