定义：
具有陶瓷微观结构的激光增益介质。

一般来讲，固态增益介质为晶体或者玻璃。晶体通常是单晶，因为多晶介质通常在边界具有很强的散射。然而，从上世纪九十年代，一种多晶介质——陶瓷通过精细的制备技术极大的降低了散射损耗，尤其是采用了真空烧结技术。

开始采用的是粉末中非常小的离子，然后经过细化工艺产生的纳米离子具有可控尺寸，非常小的微晶和气孔，得到的散射损耗比单晶大不了很多。尤其是在钇铝石榴石中已经实现。掺钕的YAG陶瓷可以得到与掺钕YAG单晶相同的激光器效率。掺镱增益介质也具有相同的性能。陶瓷也可以用做电子振动激光增益介质。

 陶瓷激光增益介质相比于单晶具有很多重要的优势： 

1. 制备成本低，尤其是制作很大片的情况下。 
2. 陶瓷增益介质可以制作成任意形状和尺寸，然而单晶增长技术则会限制介质尺寸。 
3. 陶瓷也可以产生复合增益介质，包括不同的掺杂程度，甚至不同的掺杂物。还可以包含一个可饱和吸收器用于被动Q开关。 
4. 很容易得到具有空间变化的掺杂浓度。这能够为激光器设计提供额外的自由度。 
5. 对于掺钕和掺镱YAG陶瓷，可以实现更高的掺杂浓度，但是不会产生淬灭效应降低激光器效率。 
6. 有些材料，例如氧化钇（Y2O3），氧化钪（Sc2O3）和其它钛氧化物具有很高的熔点，很难长成单晶，但是很容易得到陶瓷形式，因为烧结温度比熔点温度低很多。 Y2O3和Sc2O3的高热导率是这些材料优于YAG。 

基于以上原因，陶瓷增益介质在很多情况下可以取代戴静，尤其是在大体积应用和需要很大增益介质的情况。 需要注意的是，陶瓷用在激光器上不仅仅可以作为增益介质。有些增益介质，例如氮化铝陶瓷，具有很高的热导率，可以作为很好的电绝缘体。这也使它们可以用在高功率激光二极管中的热沉。

Definition: laser gain media which have a ceramic (polycrystalline) microscopic structure

More general term: solid-state laser gain media

Traditionally, solid-state laser gain media have been made either of crystals or glasses. In the case of crystals, these were typically single crystals (i.e., with a uniform crystal lattice throughout a large piece), because polycrystalline media usually exhibit strong scattering at domain boundaries. However, beginning in the 1990s, scattering losses of polycrystalline media with very small domains – called ceramics – have been greatly reduced with refined fabrication techniques, in particular with vacuum sintering. When the procedure is started with very small particles in the powders used and a refined treatment generates nanoparticles with a well-controlled size distribution, very small crystallites and very low porosity result, leading to scattering losses which are not significantly larger than for single crystals. This has been achieved in particular for YAG (yttrium aluminum garnet). Neodymium-doped YAG ceramics now allow for essentially the same laser efficiency as Nd:YAG single crystals. The same holds for some ytterbium-doped laser gain media. Ceramics are also suitable for vibronic laser gain media such as Cr2+:ZnSe.

Ceramic laser gain media offer a number of important advantages over single crystals:

• Their fabrication can be significantly cheaper, particularly for large pieces.
• Ceramic gain media can be fabricated with arbitrary shapes and size, whereas single-crystal growth techniques (e.g. the Czochralski method) set limits on the possible size.
• Ceramics are well suited to produce composite gain media, consisting e.g. of parts with different doping levels, or even different dopants. It is also possible to include a saturable absorber section for passive Q switching [11].
• Spatially varying doping profiles are relatively easily possible. These aspects give additional freedom in laser design.
• For neodymium-doped and ytterbium-doped YAG ceramics, a significantly higher doping concentration can be achieved without quenching effects degrading the laser efficiency.
• Some optical materials, e.g. yttria (Y2O3), scandia (Sc2O3) and other sesquioxides with their high melting temperatures, are very difficult to grow into single crystals, and much easier to obtain in ceramic form, because the sintering temperature can be much lower than the melting temperature [8]. The high thermal conductivity of Y2O3 and Sc2O3 could make these materials preferable to YAG.

For these reasons, it is conceivable that ceramic gain media will in many cases replace single crystals, particularly in high-volume applications and those which need large gain media.

Note that ceramics are interesting for laser construction not only when used as gain media. Some ceramic media, such as aluminum nitride ceramic, have a very high thermal conductivity while being excellent electrical insulators. This makes them interesting for heat sinks of high-power laser diodes.

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