  We investigate theoretically the possibility of achieving the stimulated
amplification of $\gamma$-rays. Herein, our approach circumvents the so-called
``graser dilemma" through a non-linear, multi-photon mechanism. Our work
foresees the combination of a high-intensity $\gamma-$flash generated by the
interaction of a high-intensity laser pulse with plasma and intensive photons
supplied by an additional laser. We show that multi-photon stimulated emission
processes can have a larger effective cross-section compared to a one-photon
process. The bandwidth of the supplied photons can also be tuned to curtail
linewidth broadening. Naturally, Mossbauer transitions can be chosen to apply
the scheme in the first instance. Furthermore, we derive that even multi-photon
stimulated emission in the form of an anti-Stokes type could allow our scheme
to be applied to non-Mossbauer nuclei, provided that the supplied photon energy
can be tuned to compensate for the recoil and other broadening induced losses.
The graser development can be spearheaded using multi-PW class high-power laser
systems such as the 10 PW installation at Extreme Light Infrastructure -
Nuclear Physics (ELI-NP) in Romania.
