Short, Intense Laser Pulse Makes Crystal Transparent
DOI: 10.1063/1.3034426
Although ruby is almost opaque to certain light frequencies, it can be made transparent to one of those frequencies according to Erwin Hahn and Samuel McCall of the University of California, Berkeley. The trick is to apply a sharp pulse of intense, coherent light at a frequency that matches a resonant transition in ruby. If the ruby is cold enough the pulse will be transmitted and the light can be slowed down to as little as 1% of its usual velocity. This self‐induced transparency, predicted theoretically a year and a half ago by Hahn and McCall, was recently reported by them (Phys. Rev. Letters 18, 908).