Spectral filtering of gain gratings and spectral evolution of holographic laser oscillators

We present results of the spectral filtering properties of volume gain grat ings and their role as diffractive optical elements in the spectral evoluti on of holographic laser oscillators. We show that the gain grating acts as a spectral filter with a filter bandwidth that is approximately inversely p roportional to the medium length, We investigate holographic laser oscillat ors and find that, when either the gain grating is written by monochromatic radiation or when it is initiated from broad-band radiation, the output of such oscillators can evolve to single longitudinal mode in correspondence to experimental observations.