A medical laser system including a first laser source having a first gain medium for generating a first optical field. The system further includes a first Q-switch controlling a resonance quality of the first laser source, a control circuit controlling the first Q-switch to cause the first laser source to generate the first optical field as a first pulse train of laser pulses, a second laser source for generating a second optical field as a second pulse train of laser pulses, a nonlinear medium for generating a third optical field by a nonlinear interaction between the first optical field and the second optical field, and a sensor detecting a property of at least one of the optical fields. The control circuit controls operation of the first Q-switch so as to adjust a relative timing of the laser pulses of the first pulse train and the laser pulses of the second pulse train responsive to the detected property.