Time delay gratings have in the past been set up by two brief programming pulses. However, two linear frequency chirped pulses can replace the two brief pulses giving the same effect.
This allows lower powered lasers to program high bandwidth gratings and achieve extremely fast processing. Here is an example of true time delay echoes at an extremely high rate of 4Gb/s.
Normally, echo pulses are fairly weak. By using extremely thick crystals we can get echoes with greater than 100% efficiency. This is shown below.
We have also found some exciting nutation phenomena on temporally long stimulated photon echoes that corresponds to the Rabi frequency. This is shown below.
