German scientists were able to increase the efficiency of absorption of electrons by the laser radiation. This electron beam passed through the optical resonator with whispering gallery effect in which the accumulated energy of the laser pulses. Article published in the journal Nature.
People since ancient times known effect of whispering galleries. It was observed that in the Cathedral of St. Peter in Rome whisper uttered against the wall, perfectly audible in a circle of the room, but not in the center. This is due to the fact that sound waves are reflected from the rounded walls, not absorbed them. Thus it is possible to guide and retain not only sound but light: an optical resonator of high q-factor it can save a photon more than hundreds of microseconds.