Conventional lasers use a so-called "gain medium," such as a semiconductor material, to produce a focused beam of light waves.

传统激光器通过一种所谓的“增益介质”(如半导体材料)产生聚焦光束。

youdao

Without cooling the gain medium in liquid nitrogen or using gratings and complex, expensive devices, this fiber laser has the advantages of being simple and easily attainable at a low cost.

这种装置无需将增益介质放在液氮中，也不需要多个光栅选频或其他复杂而昂贵的器件，具有结构简单，易实现和成本低等优点。

youdao

The gas flow in the gain medium is one of the main error sources in ring laser gyros.

气体增益介质的流动是激光陀螺中的一项主要误差源。

youdao

To get Anderson localisation to operate in a random laser has not been easy, mainly because it is hard to find a substance that both acts as a high-gain medium and scatters light very strongly.

ECONOMIST: Microlasers

Unlike rich countries, this argument goes, Latin America may gain more in the medium term by defending its hard-won fiscal stability and relying on the outside world for stimulus.

ECONOMIST: Latin America's economies

Will small and medium businesses be able to meet these standards and gain access to international green markets?

FORBES: Rio+20: What's Trade Got to Do with It?