Generation of single femtosecond pulses by hybrid mode-locking of a semiconductor laser

A scheme to produce single optical sub-picosecond pulses by hybrid mode locking of an external cavity laser at a repetition rate of ≈1 GHz is demonstrated. In order to obtain such ultrashort pulses the emission wavelength has to be blue-shifted from the emission maximum by a few nanometers by a reflection grating, which provides the external optical feedback. The dependence of such optical properties as pulsewidth, pulse shape, jitter, and amplitude on the implantation dose, excitation frequency and wavelength detuning is investigated. To take advantage of the almost dispersionless propagation through conventional fibers, lasers emitting at a wavelength of ≈1.3 μm are used. However, the method is applicable to semiconductor lasers emitting at any wavelength