Second harmonic generation in optical fibers. Experimental study of the self-organised holographic grating length

We report experimental results concerning self-organised holographic grating length for second harmonic generation in optical fiber. By a cut-back method of the fiber and a comparison between different laser regimes we point out the limiting factors to its extension. The grating length is found to be independent of the pulse duration. We have established experimental evidence of the limitation of the grating length by self- and cross-phase modulations effects, spectral width of the pulses and central frequency fluctuation of the laser. With a stable Nd:YAG injected laser delivering transform-limited pulses we obtain for the first time to our knowledge, holographic grating lengths above 60 cm.