Spectroscopic and mid-infrared lasing performance of rare earth doped tungsten tellurite glass fiber .
稀土掺杂碲钨酸盐玻璃光纤的光谱与中红外激光性能。
Chin describes the work as " very interesting " but says he is not yet convinced that such backward lasing could actually be used to detect pollutants and other gases .
To confirm that they had indeed generated backward lasing , the researchers placed a ccd detector a metre behind the focus and then placed a more sensitive photomultiplier tube at arbitrary angles to the beam .
However , this approach calls for a very powerful laser , and chin 's group obtained only a very small gain coefficient , which means the researchers had to ionize a long stretch of air to get any significant lasing action .