Second-harmonic generation in atomic vapor with picosecond laser pulses

摘要

Picosecond laser pulses were used to study the highly forbidden resonant second-harmonic generation (SHG) in potassium vapor. The input intensity dependence, vapor density dependence, buffer-gas pressure dependence, and spatial prove of the SHG were measured. A pump-probe experiment was conducted to probe the time dependence of the SHG signal. The experimental results can be understood from an ionization-initiated de-field-induced SHG model. A theory of a de-field-induced SHG model is developed that takes into account the time development of the de electric field in detail. This temporal buildup of the de field along with transient coherent excitation between two-photon-allowed transitions can explain the experimental results quantitatively, including the previous vapor SHG results with nanosecond laser pulses. (C) 1997 Optical Society of America.