Accumulated photon echoes by using a nonlaser light source

Accumulated photon echoes have been observed by use of a light-emitting diode. This is to our knowledge the first observation of photon echoes that are excited by a nonlaser light source. In the incoherent-light photon echo, the time resolution is equal to the inverse of the overall spectral width of the excitation light. Therefore we can easily get a high time resolution by using nonlaser light with a broad spectrum. Moreover the use of nonlaser light in the photon-echo experiment will extend the technique into wavelength regions where lasers are not currently available.