Theory of subpicosecond pulse generation by active modelocking of a semiconductor laser amplifier in an external cavity: limits for the pulsewidth

Active mode-locking of a semiconductor laser amplifier (SCLA) in an external cavity is theoretically modeled using a cosh/sup -2/ description for the optical pulses. Analytical solutions are derived. The model includes finite gainwidth, which is shown to be of the greatest importance for a correct description, and gain saturation. A lower limit of the optical pulsewidth is derived in terms of the gainwidth, the injection current, the external loss, and other parameters.<
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