Analysis and experiment on colliding pulse mode locked laser

The operation of a semiconductor colliding pulse mode locked (CPM) laser has been analyzed using the time domain approach. In this approach the re-circulating transmission of a pulse through the various elements of the optical cavity such as the gain medium, the waveguide, and, the saturable absorber is carried out with the condition that the pulse must remain unchanged after one round trip. The pulse width of a CPM laser as a function of gain section current, saturable absorber current, and, modulation frequency has been measured. The laser is similar to 8.5 mm long and operates at a pulse repetition rate of similar to 10 GHz. The measurements and modeling results agree well. Both measured and calculated minimum pulse width is similar to 1 ps.