Chirp of the pulses generated in the 1.4 mu m-1.8 mu m spectral ranges and in a singly
resonant OPO build around a 3 mm long PPLN crystal pumped at 108 MHz by 40 nJ, 1 ps
chirped or 350 fs weakly chirped pump pulses centered at 1035 nm is analyzed. Whatever
the chirp of the pump pulses, we achieved a pump to signal conversion efficiency >
30%. We demonstrate that by adjusting the cavity length around synchronism condition,
chirped or almost chirped free (down to 80 fs) signal pulses are generated. A simple
mechanism accounts for this phenomenon.
