Limiting parameters of ultrashort pulses from a Nd-doped lanthanum-beryllate laser

Experiments were carried out on a Nd-doped lanthanum beryllate laser to investigate the limiting temporal and energetic parameters of ultrashort pulses and to identify the factors limiting their values. The passive mode-locking regime of the laser was investigated using a number of dyes with different nonlinear parameters. It is found that dyes 3281 and 3321 or dyes close to them in bleaching intensity and relaxation time ensure minimum duration and maximum energy of ultrashort pulses. Ultrashort pulses of 5 and 4 ps have been obtained with dyes 3228 and 3321, respectively, with the pulse energy equal to 3 mJ (pulse power of 0.75 GW) for dye 3321.