“…Attempts have been made to reduce the beam fanning effect in PR amplifiers, for example by rotating the crystal [13], using pulsed read-out [14], using adaptive filtering in the Fourier domain [15], employing achromatic gratings [16], exploiting the faster formation rate of signal gratings compared with the noise grating [17], using signal beam chopping [18], using time-modulated amplified wave-fronts, and employing spatial averaging over the random noise distribution [19] . Control over beam fanning in counter-propagation beam geometry in BaTiO 3 , has also been reported [20] .…”