Recording of a subpicosecond time structure of output radiation pulses obtained from heterolasers with a nonlinear absorber

A precision method for recording the autocorrelation functions of the intensities of ultrashort optical pulses with a high time resolution was used in an investigation of a substructure of picosecond pulses (t_p ≈ 10–50 ps) generated by direct modulation of the current in two-component heterostructure lasers. Regular sequences of light pulses associated with passive mode locking of the internal laser resonator were recorded. In the case of long lasers, when t_p did not exceed the round-trip time in the resonator, a single spike could be generated. The minimum duration of such a spike, estimated from the average autocorrelation function, was ~ 200 fs and its peak power was ~ 20 W.