Ultrashort Pulse Generation at Quasi-40-GHz by Using a Two-Section Passively Mode-Locked InGaAsP-InP Tensile Strained Quantum-Well Laser

A 1.56 µm passively mode-locked laser diode with a two-section tensile strained multi-quantum-well structure is fabricated. Without any external pulse compression, a Lorentz pulse train with a pulse width of 1.03 ps and a repetition rate of 35.6 GHz is obtained, which is one of the best results that have been reported on similar devices. The optical pulse has a 300 kHz line width and a 50 dB peak over the noise floor in the photodetected radio-frequency electrical spectrum.